SECTION A: Definitions

Question: Define Hypertrophic scar
Correct Answer: A raised scar that remains within the boundaries of the original injury.
Explanation: This results from an overproduction of collagen during healing, but unlike a keloid, it does not extend beyond the wound margins.

Question: Define Langerhans cells
Correct Answer: Dendritic antigen-presenting cells located in the epidermis.
Explanation: They are part of the skin's immune system, responsible for capturing and presenting antigens to T-cells to initiate an immune response.

Question: Define Café-au-lait spots
Correct Answer: Uniform, light to dark brown pigmented macules or patches.
Explanation: These are benign birthmarks, and the presence of multiple spots can be associated with genetic disorders like neurofibromatosis type 1.

Question: Define Wickham's striae
Correct Answer: Fine, white, lacy or net-like lines on the surface of papules.
Explanation: This is a pathognomonic clinical sign seen in lichen planus.

Question: Define Koebner phenomenon
Correct Answer: The appearance of new skin lesions on areas of unaffected skin following trauma.
Explanation: This is characteristic of isomorphic responses in diseases like psoriasis and lichen planus.

SECTION B: Multiple Choice

Question 1: What is the most likely diagnosis?
Options:
a. Hypertrophic scar
b. Papilloma
c. Keloids
d. Granuloma
Correct Answer: c. Keloids
Explanation: The key detail is that the growths extend beyond the level of injury, which is the defining characteristic of a keloid, as opposed to a hypertrophic scar.

Question 2: What cells are involved in the pathogenesis of the above condition?
Options:
a. Keratinocytes
b. Langerhans cells
c. Melanocytes
d. Fibroblasts
Correct Answer: d. Fibroblasts
Explanation: Keloids are caused by a dysregulation of fibroblasts, leading to excessive production and reduced degradation of collagen during wound healing.

Question 3: Which of the following treatment modalities can be used in managing this condition?
Options:
a. Cryotherapy
b. Surgical removal
c. Intralesional steroids
d. All of the above
Correct Answer: d. All of the above
Explanation: Keloid management is often multimodal. Intralesional steroids are first-line to reduce collagen synthesis. Cryotherapy and surgery are also used, frequently in combination with other therapies to prevent recurrence.

Question 4: What is the function of collagen in the skin?
Options:
a. Elasticity of the skin
b. Tenacity of the skin
c. Moisture retention
d. None of the above
Correct Answer: b. Tenacity of the skin
Explanation: Collagen provides the skin with its tensile strength and structural integrity (tenacity). Elasticity is primarily provided by elastin.

Question 5: One of the major factors leading to development of the condition is
Options:
a. Reduced melanin production due to dysfunctional enzymes
b. Increased apoptosis
c. Increased melanin degeneration due to increased enzyme activity
d. Reduced melanin production due to autoimmune destruction of melanocytes
Correct Answer: d. Reduced melanin production due to autoimmune destruction of melanocytes
Explanation: Vitiligo is primarily an autoimmune disorder where melanocytes are targeted and destroyed by the immune system.

Question 6: The most common type of vitiligo seen in clinical practice is
Options:
a. Segmental vitiligo
b. Generalized vitiligo
c. Mucosal vitiligo
d. Focal vitiligo
Correct Answer: b. Generalized vitiligo
Explanation: Generalized (or non-segmental) vitiligo is the most common form, characterized by widespread, often symmetrical depigmentation.

Question 7: Which of the following may be useful in the management of this condition?
Options:
a. Dapsone
b. Hydrocortisone ointment
c. Topical PUVA
d. All of the above
Correct Answer: c. Topical PUVA
Explanation: Phototherapy, including topical PUVA, is a common treatment to stimulate repigmentation. Potent topical corticosteroids are used, but hydrocortisone is typically too weak. Dapsone is not a standard treatment.

Question 8: What is the most likely diagnosis?
Options:
a. SJS
b. Pemphigus vulgaris
c. Bacillary angiomatosis
d. Kaposi's sarcoma
Correct Answer: d. Kaposi's sarcoma
Explanation: In an HIV-positive patient, the appearance of multiple, non-painful, purple plaques and papules is highly characteristic of Kaposi's sarcoma.

Question 9: What is the most common cause of the above condition?
Options:
a. Viral infections
b. Drugs
c. Autoimmune
d. All of the above
Correct Answer: a. Viral infections
Explanation: Kaposi's sarcoma is causally linked to infection with Human Herpesvirus-8 (HHV-8).

Question 10: What is commonly seen on histology?
Options:
a. Spindle cells
b. Hemosiderin deposition
c. Extravasated RBCs
d. All of the above
Correct Answer: d. All of the above
Explanation: The histology is characterized by proliferating spindle cells, slit-like vascular spaces, extravasated red blood cells, and hemosiderin deposition.

Question 11: Which group of drugs may be beneficial in treating the above condition?
Options:
a. Corticosteroids
b. Antiretroviral agents
c. Antibiotics
d. Anti-fungal drugs
Correct Answer: b. Antiretroviral agents
Explanation: Initiating or optimizing antiretroviral therapy (ART) is fundamental to managing HIV-associated Kaposi's sarcoma, as immune reconstitution can cause lesion regression.

Question 12: Which childhood infection is associated with Koplik spots?
Options:
a. Chicken pox
b. Measles
c. Rubella
d. Fifth disease
Correct Answer: b. Measles
Explanation: Koplik spots are pathognomonic for measles (rubeola) and appear as small white spots on the buccal mucosa.

Question 13: What is the infective agent implicated in acne?
Options:
a. Staphylococcus aureus
b. Streptococcus pyogenes
c. Propionibacterium acnes
d. Staphylococcus epidermidis
Correct Answer: c. Propionibacterium acnes
Explanation: Cutibacterium acnes (formerly Propionibacterium acnes) is the primary bacterium involved in the inflammation of acne vulgaris.

Question 14: What skin condition is caused by a poxvirus?
Options:
a. Varicella
b. Verruca
c. Molluscum contagiosum
d. Impetigo
Correct Answer: c. Molluscum contagiosum
Explanation: Molluscum contagiosum is caused by the Molluscum contagiosum virus, a member of the poxvirus family.

Question 15: Common presentations include all of the following except:
Options:
a. Gumma
b. Aortitis
c. Chancre
d. Tabes dorsalis
Correct Answer: c. Chancre
Explanation: A chancre is the primary lesion of syphilis. Gummas, cardiovascular manifestations like aortitis, and neurosyphilis (e.g., tabes dorsalis) are features of tertiary syphilis.

SECTION C: Fill in the Blanks

Question 1: The skin is histologically characterized by three layers. These are the epidermis, the dermis, and the hypodermis. Some of the functions of skin are protection, thermoregulation, and sensation. Keratinocytes are the predominant cells of the skin.

Question 2: Atopic dermatitis may be associated with a mutation of the filaggrin gene. In adults, it mostly affects the flexures; in children, it is usually present on the face and extensor surfaces. Common drugs used in management of atopic dermatitis are topical corticosteroids and topical calcineurin inhibitors (e.g., Tacrolimus).

SECTION A (10 Marks): Definitions

1. Question: Define Auspitz sign
Correct Answer: Pinpoint bleeding after removal of scales in psoriasis.
Explanation: Psoriatic lesions have thin suprapapillary plates and dilated dermal capillaries. When scales are gently scraped off, these capillaries rupture, producing pinpoint bleeding — a diagnostic hallmark of psoriasis.

2. Question: Define Target lesion
Correct Answer: A round skin lesion with three concentric color zones — a dark center (blister or crust), a pale pink raised middle ring (due to edema), and a bright red outer ring.
Explanation: These lesions are typical of erythema multiforme and indicate a reactive inflammatory pattern often triggered by infections or drugs.

3. Question: Define Plaque
Correct Answer: A circumscribed, palpable, elevated lesion greater than 1 cm in diameter with a flat surface.
Explanation: Plaques often arise from the merging of papules and are characteristic of chronic dermatoses such as psoriasis.

4. Question: Define Vesicle
Correct Answer: A circumscribed, fluid-filled elevation of the skin measuring ≤1 cm in diameter.
Explanation: Vesicles contain clear or serous fluid and are seen in conditions like herpes zoster and eczema.

5. Question: Define Hive (Wheal)
Correct Answer: A transient, raised area of skin due to localized dermal edema, pale centrally with an erythematous rim.
Explanation: Also called a wheal, it is the hallmark lesion of urticaria and forms due to histamine-induced increased vascular permeability.

SECTION B (30 Marks): Multiple Choice

🧩 Case 1

A 29-year-old HIV-positive male presents with vesicles and pustules on an erythematous base in a dermatomal distribution on the back. The lesions are itchy and painful.

1. Question: What is the most likely causative agent for this rash?
Options:
A. Human herpesvirus type 1 or 2
B. Human herpesvirus type 3
C. Staphylococcus aureus
D. Staphylococcus epidermidis
Correct Answer: B. Human herpesvirus type 3
Explanation: HHV-3 (Varicella-Zoster virus) causes Herpes zoster (shingles), characterized by painful, grouped vesicles along a dermatome in immunocompromised individuals such as HIV patients.

2. Question: Which of the following secondary lesions is unlikely to result from this rash?
Options:
A. Erosion
B. Crust
C. Lichenification
D. Excoriation
Correct Answer: C. Lichenification
Explanation: Lichenification (skin thickening from chronic scratching) is not a typical secondary lesion in herpes zoster. The others (erosion, crust, excoriation) commonly follow vesicle rupture or scratching.

3. Question: Which of the following agents is ideal in the treatment of this condition?
Options:
A. Fluconazole
B. Acyclovir
C. Cloxacillin
D. Mupirocin
Correct Answer: B. Acyclovir
Explanation: Acyclovir is the antiviral of choice for Herpes zoster, reducing pain and preventing complications like postherpetic neuralgia.

🧩 Case 2

A 6-year-old female presents with slowly progressing hypopigmented patches on the face and chest. Lesions are non-itchy and non-painful.

4. Question: What is the most likely diagnosis?
Options:
A. Urticaria
B. Vertigo
C. Lichen planus
D. None of the above
Correct Answer: D. None of the above (Vitiligo)
Explanation: The described presentation fits vitiligo — depigmented, non-scaly, non-itchy patches due to autoimmune destruction of melanocytes.

5. Question: Which hypersensitivity reaction may be involved in the pathogenesis of this condition?
Options:
A. Type 1
B. Type 2
C. Type 3
D. Type 4
Correct Answer: D. Type 4
Explanation: Vitiligo involves cell-mediated (Type IV) autoimmune destruction of melanocytes, primarily via cytotoxic T lymphocytes.

6. Question: Which of the following may be useful in the management of this condition?
Options:
A. Topical antifungal
B. Topical antibiotic
C. Topical steroid
D. Topical antiviral
Correct Answer: C. Topical steroid
Explanation: Topical corticosteroids help to suppress local immune destruction and promote repigmentation in vitiligo.

🧩 Case 3

A 15-year-old female presents with annular patches on the hands. The patches clear in the center, extend at the periphery, and are scaly and itchy.

7. Question: What is the diagnosis?
Options:
A. Tinea manus
B. Tinea corporis
C. Tinea cruris
D. Erythema marginatum
Correct Answer: A. Tinea manus
Explanation: Fungal infection of the hands by dermatophytes causes annular, scaly lesions with central clearing — ringworm of the hand.

8. Question: How would you confirm the diagnosis?
Options:
A. KOH microscopy
B. Skin biopsy
C. DNA PCR
D. None of the above
Correct Answer: A. KOH microscopy
Explanation: A potassium hydroxide (KOH) mount dissolves keratin, allowing visualization of branching hyphae — diagnostic for dermatophytosis.

9. Question: Which of the following can be used to treat this condition?
Options:
A. Topical antifungal
B. Topical antibiotic
C. Topical antiviral
D. Topical calcineurin inhibitor
Correct Answer: A. Topical antifungal
Explanation: Topical antifungals (e.g., clotrimazole, terbinafine) are the mainstay of therapy for tinea infections.

🧩 Case 4

A 7-year-old female presents with itchy, oozing patches on the antecubital and popliteal fossae. Recurrent during cold seasons.

10. Question: What is the diagnosis?
Options:
A. Urticaria
B. Pompholyx
C. Atopic eczema
D. Cutaneous herpes simplex infection
Correct Answer: C. Atopic eczema
Explanation: Flexural eczema with itching and oozing in a child strongly suggests atopic dermatitis, especially with recurrent episodes.

11. Question: Which gene may be associated with the development of this condition?
Options:
A. Filaggrin gene
B. Nucleotide excision repair gene
C. Tyrosinase gene
D. None of the above
Correct Answer: A. Filaggrin gene
Explanation: Mutations in the filaggrin (FLG) gene lead to skin barrier dysfunction, predisposing to atopic dermatitis.

12. Question: Which of the following is not useful in the management of this condition?
Options:
A. Emollient
B. Antihistamine
C. Topical calcineurin inhibitor
D. Acyclovir
Correct Answer: D. Acyclovir
Explanation: Acyclovir treats viral infections, not eczema. Emollients, antihistamines, and calcineurin inhibitors are standard management options.

🧩 Case 5

A 40-year-old female presents with erythematous, scaly plaques on elbows, knees, and scalp for 10 years; non-itchy.

13. Question: What is the diagnosis?
Options:
A. Psoriasis
B. Lichen planus
C. Seborrheic dermatitis
D. Tinea corporis
Correct Answer: A. Psoriasis
Explanation: Chronic, well-demarcated, scaly plaques on extensor surfaces are classic for psoriasis.

14. Question: Which sign can be elicited in this condition?
Options:
A. Nikolsky’s sign
B. Darier’s sign
C. Hutchinson’s sign
D. Auspitz sign
Correct Answer: D. Auspitz sign
Explanation: Pinpoint bleeding upon scale removal is diagnostic for psoriasis.

15. Question: What nail changes are commonly seen in this condition?
Options:
A. Nail pitting
B. Oil spots
C. Leukonychia
D. All of the above
Correct Answer: D. All of the above
Explanation: Psoriasis can present with nail pitting, oil-drop discoloration, and leukonychia.

16. Question: Which of the following can NOT be used in the treatment of this condition?
Options:
A. Coal tar ointment and shampoo
B. Prednisolone tablets
C. Clobetasol propionate ointment
D. Methotrexate
Correct Answer: B. Prednisolone tablets
Explanation: Systemic steroids are contraindicated in psoriasis due to risk of rebound flares and pustular psoriasis.

🧩 Case 6

A 9-year-old girl presents with massive growths on the chest after traditional tattooing; growths extend beyond injury.

17. Question: What is the diagnosis?
Options:
A. Hypertrophic scars
B. Keloids
C. Atrophic scars
D. All of the above
Correct Answer: B. Keloids
Explanation: Keloids extend beyond the original wound boundaries, unlike hypertrophic scars.

18. Question: Which cells in the skin are involved in the pathogenesis of this condition?
Options:
A. Fibroblasts
B. Keratinocytes
C. Merkel cells
D. Langerhans cells
Correct Answer: A. Fibroblasts
Explanation: Fibroblasts are responsible for excess collagen deposition leading to keloid formation.

19. Question: Which of the following treatment modalities would you use for managing this condition?
Options:
A. Intralesional steroid injections
B. Conservative management
C. Oral corticosteroids
D. None of the above
Correct Answer: A. Intralesional steroid injections
Explanation: Intralesional corticosteroids (e.g., triamcinolone) inhibit fibroblast activity and collagen synthesis, flattening keloids.

🧩 Case 7

A 22-year-old heterosexual male presents with cauliflower-like keratotic growths on the penis, painless and slowly increasing.

20. Question: What is the likely cause of this condition?
Options:
A. Human herpesvirus
B. Human papillomavirus
C. Treponema pallidum
D. Varicella-Zoster virus
Correct Answer: B. Human papillomavirus
Explanation: Condyloma acuminata (genital warts) are caused by HPV, typically types 6 and 11.

21. Question: Which of the following is NOT a treatment option for this condition?
Options:
A. Cryotherapy
B. Intralesional steroids
C. Trichloroacetic acid
D. Imiquimod cream
Correct Answer: B. Intralesional steroids
Explanation: Steroids are not used for warts. Chemical ablation, cryotherapy, and immune-modulating creams like imiquimod are effective.

🧩 Case 8 — Stevens-Johnson Syndrome / Toxic Epidermal Necrolysis

22. Question: What is the most common cause in adults?
Options:
A. Viral infections
B. Drugs
C. Food allergies
D. UV radiation
Correct Answer: B. Drugs
Explanation: Drugs (especially sulfonamides, antiepileptics, NSAIDs) are the leading cause of SJS/TEN in adults.

23. Question: Which sign is present?
Options:
A. Asboe-Hansen sign
B. Auspitz sign
C. Darier’s sign
D. Hutchinson’s sign
Correct Answer: A. Asboe-Hansen sign
Explanation: Asboe-Hansen (extension of a blister on pressure) and Nikolsky’s sign are both positive due to epidermal detachment.

24. Question: What lesions are commonly seen?
Options:
A. Target lesions
B. Nodules
C. Scales
D. Trophi
Correct Answer: A. Target lesions
Explanation: Target or iris lesions with central necrosis are typical cutaneous features of SJS/TEN.

25. Question: What do you expect to see on histology?
Options:
A. Necrosis
B. Acanthosis
C. Parakeratosis
D. None of the above
Correct Answer: A. Necrosis
Explanation: Histology shows widespread epidermal necrosis and subepidermal bullae.

26. Question: What complications are anticipated?
Options:
A. Fluid and electrolyte imbalance
B. Hypothermia
C. Sepsis
D. All of the above
Correct Answer: D. All of the above
Explanation: Severe epidermal loss leads to dehydration, infection, and hypothermia — similar to burns.

27. Question: Which of the following is an important aspect of management?
Options:
A. Fluid maintenance
B. Temperature regulation
C. Withdrawal of causative drug
D. All of the above
Correct Answer: D. All of the above
Explanation: SJS/TEN management is supportive: stop the causative drug, maintain fluids, and prevent infection/hypothermia.

SECTION C (20 Marks): Fill in the Blanks

1. Question: The seven P’s representing the symptoms and signs of lichen planus include:
Answer: Purple, Pruritic, Polygonal, Peripheral, Papules, Plaques, and Planar (flat-topped).
Explanation: These alliterative features describe the classical morphology of lichen planus lesions.

2. Question: On histopathology, Kaposi’s sarcoma is characterized by:
Answer: (i) Prominent spindle cells, (ii) Slit-like vascular spaces, and (iii) Extravasation of red blood cells.
Explanation: These findings reflect the vascular neoplasm caused by HHV-8 infection.

SECTION D (8 Marks): True or False

1. Statement: A plaque is a flat circumscribed lesion greater than 1 cm in diameter.
Answer: True
Explanation: A plaque is an elevated, flat-topped, circumscribed lesion measuring more than 1 cm in diameter — typical in conditions like psoriasis.

2. Statement: Kaposi’s sarcoma is caused by human papilloma virus type 8.
Answer: False
Explanation: Kaposi’s sarcoma is caused by Human Herpesvirus type 8 (HHV-8), not by human papillomavirus (HPV).

3. Statement: Desmogleins are the autoantigens in pemphigus vulgaris.
Answer: True
Explanation: In pemphigus vulgaris, autoantibodies target desmoglein-1 and desmoglein-3, components of desmosomes that hold keratinocytes together, leading to intraepidermal blistering.

4. Statement: Immunoglobulin E is involved in the pathogenesis of urticaria.
Answer: True
Explanation: Urticaria is an IgE-mediated type I hypersensitivity reaction. IgE binds to mast cells, causing histamine release and formation of wheals (hives).

5. Statement: Fibroblasts are cells of the dermis and produce fibrin.
Answer: False
Explanation: Fibroblasts are indeed dermal cells, but they produce collagen, elastin, and proteoglycans, not fibrin. Fibrin is formed from fibrinogen during blood clotting.

6. Statement: A fissure is a linear erosion caused by scratching.
Answer: True
Explanation: A fissure is a linear crack or break in the epidermis or dermis, often caused by dryness or repeated scratching.

7. Statement: KOH microscopy can be used to confirm tinea capitis.
Answer: True
Explanation: A potassium hydroxide (KOH) mount reveals fungal hyphae or spores in infected hair shafts, confirming dermatophyte infection like tinea capitis.

8. Statement: Atopic eczema in children commonly affects the flexor surfaces.
Answer: False
Explanation: In children, atopic eczema typically affects the extensor surfaces (like elbows and knees) and the face. Flexural involvement is more common in adults.

SECTION A

5 Definations

SECTION B

Question 1

A 35-year-old woman develops an itchy rash over her back, legs, and trunk several hours after swimming in a lake. Erythematous, edematous papules and plaques are noted. The wheals vary in size. There are no mucosal lesions and no swelling of the lips. What is the best first step in management of her symptoms?

Options:
A. Subcutaneous epinephrine
B. Intravenous glucocorticoids
C. Oral antihistamines (H1 blockers)
D. Aspirin
E. Oral doxycycline

Correct Answer: C. Oral antihistamines (H1 blockers)

Detailed Explanation:
This presentation describes acute urticaria (hives), characterized by transient, pruritic wheals due to histamine release from mast cells. It often follows exposure to allergens or physical stimuli such as cold water (aquagenic or cold-induced urticaria).

• First-line treatment: Non-sedating oral H1 antihistamines (e.g., cetirizine, loratadine).
  
  

• Epinephrine is reserved for anaphylaxis (with airway compromise or angioedema).
  
  

• Steroids may be used if severe or chronic, but not as first-line.
  
  

• Aspirin and antibiotics have no role.
  
  

Question 2

The main difference between Impetigo and Ecthyma is:

Options:
A. Epidermal ulceration
B. Etiological organisms
C. Involvement of resistant organisms
D. Systemic distribution of toxin
E. All of the above

Correct Answer: A. Epidermal ulceration

Detailed Explanation:

• Impetigo is a superficial skin infection confined to the epidermis, commonly caused by Staphylococcus aureus or Streptococcus pyogenes.
  
  

• Ecthyma is a deeper form of impetigo extending into the dermis, producing ulcerated lesions covered with thick crusts.
  Thus, the key distinguishing feature is epidermal ulceration (deeper dermal involvement in ecthyma).
  
  

Question 3

Bullous impetigo is caused by local production of a toxin produced by ______ that acts to cleave ______.

Options:
A. Group A Streptococcus, desmocollins
B. Group A Streptococcus, desmoglein
C. Staphylococcus aureus, desmoglein
D. Staphylococcus aureus, desmocollins
E. Staphylococcus epidermidis, hemidesmosomes

Correct Answer: C. Staphylococcus aureus, desmoglein

Detailed Explanation:
Bullous impetigo is caused by Staphylococcus aureus strains that produce exfoliative toxin A, which specifically cleaves desmoglein-1, a desmosomal adhesion protein in the upper epidermis.
This results in flaccid bullae that rupture easily, leaving honey-colored crusts.
The same toxin is responsible for staphylococcal scalded skin syndrome (SSSS), but in that case, it acts systemically.

Question 4

Complications arising from cutaneous infections with Group A Streptococcus are:

Options:
A. Rheumatic fever
B. Glomerulonephritis
C. Scarlet fever
D. B and C only
E. A, B, and C

Correct Answer: D. B and C only

Detailed Explanation:
Group A β-hemolytic Streptococcus pyogenes causes skin infections such as impetigo and erysipelas.

• Rheumatic fever follows throat infections, not skin infections.
  
  

• Post-streptococcal glomerulonephritis and scarlet fever may follow cutaneous infection due to streptococcal toxin production and immune complex deposition.
  Hence, the correct complications are glomerulonephritis and scarlet fever.
  
  

Question 5

When staphylococcal scalded skin syndrome occurs in adults, it is often associated with pre-existing:

Options:
A. Complement deficiencies
B. Liver failure
C. Renal insufficiency
D. Tampon use
E. All of the above

Correct Answer: C. Renal insufficiency

Detailed Explanation:
Staphylococcal Scalded Skin Syndrome (SSSS) in adults is rare and typically linked to renal failure, which impairs clearance of S. aureus exfoliative toxins (A and B).
In children, immature kidneys explain susceptibility, but in adults, toxin accumulation due to renal insufficiency or immunosuppression (e.g., HIV, malignancy) allows systemic toxin effects.
Tampon use is associated with toxic shock syndrome, not SSSS.

Question 6

In comparison to ordinary cellulitis, erysipelas is distinguished by ______ often occurring in the face or lower extremities.

Options:
A. Brighter erythema, well-demarcated lesions
B. Brighter erythema, poorly demarcated lesions
C. Duskier erythema, poorly demarcated lesions
D. Duskier erythema, well-demarcated lesions
E. None of the above

Correct Answer: A. Brighter erythema, well-demarcated lesions

Detailed Explanation:
Erysipelas is a superficial form of cellulitis involving the upper dermis and lymphatics, most commonly caused by Streptococcus pyogenes.

• It presents with bright red, raised, and sharply demarcated borders, often on the face or lower legs.
  Cellulitis, in contrast, involves deeper dermal and subcutaneous tissues, producing poorly defined erythema.
  
  

Question 7

Necrotizing fasciitis is characterized by:

Options:
A. A need for a deep incisional biopsy for diagnosis
B. Ischemia, thrombosis, and tissue necrosis
C. Pain out of proportion to physical findings
D. Rapid spread
E. All of the above

Correct Answer: E. All of the above

Detailed Explanation:
Necrotizing fasciitis is a rapidly progressive, life-threatening infection involving fascia and subcutaneous tissues.

• Caused by Streptococcus pyogenes, Staphylococcus aureus, or mixed anaerobic flora.
  
  

• Features: Severe pain disproportionate to visible findings, swelling, crepitus, skin discoloration, and systemic toxicity.
  
  

• Diagnosis: Requires urgent surgical exploration or deep biopsy.
  
  

• Management: Immediate surgical debridement and broad-spectrum IV antibiotics.
  
  

Question 8

Hot tub folliculitis is caused by:

Options:
A. Erysipelothrix rhusiopathiae
B. Group A Streptococcus
C. Pseudomonas aeruginosa
D. Staphylococcus aureus
E. Staphylococcus epidermidis

Correct Answer: C. Pseudomonas aeruginosa

Detailed Explanation:
Hot tub folliculitis results from infection of hair follicles by Pseudomonas aeruginosa, often after using inadequately chlorinated hot tubs or pools.

• Lesions: Multiple pruritic, erythematous papules or pustules on areas covered by swimwear.
  
  

• Usually self-limited; may require antipseudomonal antibiotics (e.g., ciprofloxacin) if severe.
  
  

Question 9

The most common pathognomonic sign of acne is the presence of:

Options:
A. Comedone
B. Pustule
C. Papule
D. Cyst

Correct Answer: A. Comedone

Detailed Explanation:
Comedones (blackheads and whiteheads) are the hallmark lesions of acne vulgaris, representing keratinous plugs within dilated pilosebaceous ducts.

• Open comedones (blackheads): Keratin oxidizes, turning dark.
  
  

• Closed comedones (whiteheads): Covered by thin epithelium.
  Inflammatory lesions (papules, pustules, cysts) may develop secondarily.
  
  

Question 10

Which of the following can cause acneiform lesions?

Options:
A. Tretinoin
B. Azelaic acid
C. Corticosteroids
D. Adapalene

Correct Answer: C. Corticosteroids

Detailed Explanation:
Acneiform eruptions resemble acne but lack comedones and appear suddenly. They are commonly drug-induced.
Corticosteroids (especially systemic or potent topical forms) can induce steroid acne, characterized by monomorphic papules and pustules on the chest, back, and face.
Tretinoin, adapalene, and azelaic acid are topical anti-acne agents.

Question 11

Which of the following is used as an oral medicine for acne?

Options:
A. Azelaic acid
B. Tretinoin
C. Adapalene
D. Isotretinoin

Correct Answer: D. Isotretinoin

Detailed Explanation:
Isotretinoin is an oral retinoid (vitamin A derivative) used for severe, nodulocystic, or treatment-resistant acne.
It works by reducing sebaceous gland size, sebum production, keratinization, and Propionibacterium (Cutibacterium) acnes colonization.
Topical retinoids like tretinoin, adapalene, and azelaic acid are used for mild to moderate acne, not as oral agents.
⚠️ Teratogenic — contraindicated in pregnancy.

Question 12

Regarding Acne Vulgaris, which one is the least suitable to be included in the pathogenic factors?

Options:
A. Hyperkeratosis of epidermal cells at the orifice of pilosebaceous ducts
B. Increased activity of sebaceous glands
C. Hyperproliferation of P. acnes
D. Inflammation of the pilosebaceous unit
E. Decreased activity of androgens

Correct Answer: E. Decreased activity of androgens

Detailed Explanation:
Pathogenesis of acne vulgaris involves four main factors:

1. Follicular hyperkeratinization → blockage of pilosebaceous ducts.
   
   

2. Increased sebum production → stimulated by androgens.
   
   

3. Colonization by Cutibacterium acnes (formerly P. acnes).
   
   

4. Inflammation of the follicle.
   Thus, decreased activity of androgens is not a cause — in fact, androgen excess promotes acne formation.
   
   

Question 13

A 28-year-old patient was diagnosed with borderline leprosy and started on multibacillary multidrug therapy. Six weeks later, he developed pain in the nerves and redness and swelling of the skin lesions.

The management of his illness should include all of the following except:

Options:
A. Stop anti-leprosy drug
B. Systemic corticosteroids
C. Rest to the affected limbs
D. Analgesics

Correct Answer: A. Stop anti-leprosy drug

Detailed Explanation:
This scenario describes a Type 1 (reversal) lepra reaction, an acute inflammatory episode occurring in borderline leprosy due to increased cell-mediated immunity.

• Management: Continue anti-leprosy drugs (to avoid relapse).
  
  

• Give systemic corticosteroids (e.g., prednisolone) to reduce inflammation and prevent nerve damage.
  
  

• Provide analgesics and limb rest for comfort.
  Stopping multidrug therapy is contraindicated.
  
  

Question 14

What is your diagnosis of this sudden condition?

Options:
A. Type 1 lepra reaction
B. Type 2 lepra reaction
C. Both A & B
D. Neither A nor B

Correct Answer: A. Type 1 lepra reaction

Detailed Explanation:
Type 1 (reversal) reaction occurs in borderline leprosy due to enhancement of cell-mediated immunity against M. leprae.

• Characterized by inflammation of existing lesions and nerve tenderness.
  
  

• It can lead to nerve damage and deformities if untreated.
  Type 2 (erythema nodosum leprosum) occurs in lepromatous leprosy due to immune complex deposition (Type III hypersensitivity) and presents with new tender nodules.
  
  

Question 15

What type of hypersensitivity reaction is involved in the pathogenesis of this condition?

Options:
A. Type 1 hypersensitivity
B. Type 2 hypersensitivity
C. Type 3 hypersensitivity
D. Type 4 hypersensitivity

Correct Answer: D. Type 4 hypersensitivity

Detailed Explanation:
Type 1 lepra reaction is mediated by Type IV (delayed-type) hypersensitivity, reflecting a heightened cell-mediated immune response against M. leprae.
It involves Th1 lymphocytes, macrophages, and cytokines like IFN-γ, leading to inflammation of nerves and skin lesions.
By contrast, Type 2 lepra reaction (ENL) is Type III hypersensitivity, caused by immune complex deposition.

Question 16

Cell-mediated immunity is maximally suppressed in:

Options:
A. Borderline leprosy
B. Lepromatous leprosy
C. Tuberculoid leprosy
D. Indeterminate leprosy

Correct Answer: B. Lepromatous leprosy

Detailed Explanation:
Leprosy exists on a spectrum based on host immune response:

• Tuberculoid leprosy: Strong cell-mediated immunity → few lesions, few bacilli.
  
  

• Lepromatous leprosy: Weak or absent cell-mediated immunity → numerous bacilli and widespread lesions.
  Therefore, lepromatous leprosy shows the maximum suppression of cell-mediated immunity.
  
  

Question 17

Erythema Nodosum Leprosum (ENL) is commonly seen in:

Options:
A. Tuberculoid leprosy
B. Borderline leprosy
C. Lepromatous leprosy
D. Indeterminate leprosy

Correct Answer: C. Lepromatous leprosy

Detailed Explanation:
Erythema Nodosum Leprosum (ENL) is a Type 2 lepra reaction occurring in lepromatous or borderline lepromatous leprosy.

• It is caused by immune complex deposition (Type III hypersensitivity).
  
  

• Clinically presents with painful erythematous nodules, fever, and systemic symptoms.
  
  

• Treated with systemic corticosteroids or thalidomide (in non-pregnant adults).
  
  

Question 18

Apocrine glands produce:

Options:
A. Mucus
B. Sebum
C. Sweat
D. Keratin

Correct Answer: C. Sweat

Detailed Explanation:
Apocrine glands are specialized sweat glands located in the axilla, anogenital region, and areola.
They secrete a thick, protein-rich sweat into hair follicles, which becomes odorous due to bacterial decomposition.

• Eccrine glands: produce watery sweat for thermoregulation.
  
  

• Sebaceous glands: secrete sebum, an oily substance.
  
  

Question 19

Which of the following infections is also known as ringworm?

Options:
A. Folliculitis
B. Herpes simplex
C. Impetigo
D. Tinea corporis

Correct Answer: D. Tinea corporis

Detailed Explanation:
Tinea corporis (ringworm of the body) is a superficial dermatophyte infection caused by Trichophyton, Microsporum, or Epidermophyton species.
It presents as annular, scaly lesions with central clearing and raised active borders.
The name “ringworm” comes from its ring-like appearance — not because of any worm.

Question 20

Which of the following conditions is characterized by a scaly dermatitis affecting parts of the skin supplied by oil glands?

Options:
A. Chronic dermatitis
B. Acne
C. Eczema
D. Seborrheic dermatitis

Correct Answer: D. Seborrheic dermatitis

Detailed Explanation:
Seborrheic dermatitis is a chronic inflammatory condition affecting sebaceous (oil gland-rich) areas — scalp, face (nasolabial folds, eyebrows), chest, and behind the ears.
It is associated with overgrowth of Malassezia furfur.
Lesions appear as greasy, yellowish scales with mild itching.
In infants, it causes cradle cap; in adults, may worsen with stress or HIV.

Question 21

The vascular layer of the skin is the:

Options:
A. Dermis
B. Epidermis
C. Stratum corneum
D. Stratum basale

Correct Answer: A. Dermis

Detailed Explanation:
The dermis is the vascular and connective tissue layer of the skin lying beneath the epidermis.
It contains blood vessels, lymphatics, nerves, sebaceous glands, sweat glands, and hair follicles.
In contrast, the epidermis is avascular and depends on the dermis for nutrient and oxygen diffusion.

• Stratum corneum and stratum basale are sublayers of the epidermis.
  
  

Question 22

What is the growth phase of a hair follicle?

Options:
A. Anagen
B. Catagen
C. Growagen
D. Telogen

Correct Answer: A. Anagen

Detailed Explanation:
Hair growth occurs in cycles with three main phases:

1. Anagen phase (growth phase): Active hair growth; lasts 2–6 years.
   
   

2. Catagen phase (transitional phase): Short involution phase lasting 2–3 weeks.
   
   

3. Telogen phase (resting/shedding phase): Hair falls out and follicle rests before returning to anagen.
   Thus, Anagen is the true growth phase of the hair follicle.
   
   

Question 23

Which of the following organisms is involved in the pathogenesis of Seborrheic dermatitis?

Options:
A. Staphylococcus aureus
B. Clostridium tetani
C. Malassezia furfur
D. Candida albicans

Correct Answer: C. Malassezia furfur

Detailed Explanation:
Seborrheic dermatitis is a chronic inflammatory skin disorder associated with overgrowth of the lipophilic yeast Malassezia furfur (formerly Pityrosporum ovale).
The organism thrives in sebaceous (oil-producing) areas, such as the scalp, face, and upper trunk.
It causes greasy scales, erythema, and mild itching.
Antifungal agents like ketoconazole help control it by reducing Malassezia overgrowth.

Question 24

Which antibody is responsible for atopy?

Options:
A. IgA
B. IgE
C. IgG
D. IgM

Correct Answer: B. IgE

Detailed Explanation:
Atopy refers to a genetic predisposition to develop allergic diseases such as asthma, allergic rhinitis, and atopic dermatitis.
It is mediated by IgE antibodies, which bind to mast cells and basophils.
Upon allergen exposure, cross-linking of IgE triggers histamine release, leading to itching, redness, and swelling.
IgE-mediated reactions are Type I hypersensitivity reactions.

Question 25

An ulcer is:

Options:
A. Shallow epidermal defect
B. Break in epidermis with exposure of dermis
C. A primary skin lesion
D. A, B, & C
E. None of the above

Correct Answer: B. Break in epidermis with exposure of dermis

Detailed Explanation:
An ulcer is a secondary skin lesion formed by loss of the epidermis and part of the dermis, exposing the underlying tissue.
It may result from infection, trauma, vascular insufficiency, or neoplasia.
It differs from:

• Erosion: loss of only epidermis.
  
  

• Fissure: linear crack.
  
  

• Excoriation: scratch-induced loss of epidermis.
  Ulcers often heal with scarring.
  
  

Question 26

What is a Bulla?

Options:
A. A large vesicle
B. Hives
C. A large cyst
D. A secondary skin lesion
E. None of the above

Correct Answer: A. A large vesicle

Detailed Explanation:
A bulla (plural: bullae) is a large fluid-filled blister (>0.5 cm in diameter) containing serous or seropurulent fluid.
It is a primary skin lesion.
Seen in conditions such as bullous pemphigoid, burns, or insect bites.
Smaller fluid-filled lesions (<0.5 cm) are called vesicles.

Question 27

Dried exudate on the surface of the skin is:

Options:
A. Vesicle
B. Pustule
C. Scale
D. Crust

Correct Answer: D. Crust

Detailed Explanation:
A crust forms when serum, blood, or pus dries on the skin surface.
It is a secondary lesion seen in conditions such as impetigo, eczema, or herpes infection.

• Scale: flake of keratinized epithelium.
  
  

• Pustule: a small, pus-filled elevation.
  Thus, dried exudate = crust.
  
  

Question 28

Another term for itching is:

Options:
A. Dermatitis
B. Keratosis
C. Hyperkeratosis
D. Pruritus

Correct Answer: D. Pruritus

Detailed Explanation:
Pruritus is the medical term for itching, an unpleasant sensation that provokes the desire to scratch.
It can be localized (e.g., eczema, insect bites) or generalized (e.g., liver disease, renal failure, Hodgkin lymphoma).
Itching may be a symptom of primary skin disease or systemic disorder.

Question 29

The brown-black pigment of the skin that is transferred to other epidermal cells and gives the skin its color is called:

Options:
A. Bilirubin
B. Keratin
C. Elastin
D. Melanin

Correct Answer: D. Melanin

Detailed Explanation:
Melanin is the pigment produced by melanocytes in the basal layer of the epidermis.
It provides skin, hair, and eye color and protects against ultraviolet radiation.
Melanin is transferred from melanocytes to keratinocytes.

• Bilirubin: yellow pigment from heme breakdown.
  
  

• Keratin: structural protein.
  
  

• Elastin: gives elasticity to connective tissue.
  
  

Question 30

What is the main cell type in the dermis?

Options:
A. Keratinocyte
B. Fibroblast
C. Melanocyte
D. Langerhans cell

Correct Answer: B. Fibroblast

Detailed Explanation:
The dermis is primarily composed of fibroblasts, which synthesize collagen, elastin, and ground substance — providing strength and elasticity.
Other dermal components include macrophages, mast cells, and lymphocytes.

• Keratinocytes are the main cells in the epidermis, not dermis.
  
  

• Melanocytes produce pigment in the basal layer.
  
  

• Langerhans cells are epidermal antigen-presenting cells.
  
  

SECTION C

1. Scale is an accumulation of fragments of the stratum corneum.

Correct Answer: ✅ True
Explanation: A scale is a flake or accumulation of keratinized cells from the stratum corneum (outermost skin layer). It is seen in conditions such as psoriasis and seborrheic dermatitis.

2. Circumscribed lesion that is raised and consists of edema is urticaria.

Correct Answer: ✅ True
Explanation: Urticaria (wheals/hives) are transient, raised, erythematous lesions caused by localized dermal edema due to histamine release. They are usually pruritic (itchy).

3. Dermatophytes are deep fungal infections.

Correct Answer: ❌ False
Explanation: Dermatophytes cause superficial fungal infections (tinea/ringworm) of keratinized tissues — skin, hair, and nails — not deep tissues. Deep fungal infections are caused by organisms like Sporothrix schenckii or Blastomyces dermatitidis.

4. Cutis rhomboidalis nuchae is a sign of skin aging.

Correct Answer: ✅ True
Explanation: Cutis rhomboidalis nuchae is a photoaging change caused by chronic sun exposure, seen as thickened, leathery, rhomboid-patterned skin on the posterior neck. It is indeed a sign of actinic (sun-induced) skin aging.

5. Athlete’s foot is another term for Tinea cruris.

Correct Answer: ❌ False
Explanation: Athlete’s foot refers to Tinea pedis, a dermatophyte infection of the feet, particularly the interdigital areas.
Tinea cruris is “jock itch”, an infection of the groin region.

6. The bacteria can be found in lesions of primary syphilis.

Correct Answer: ✅ True
Explanation: In primary syphilis, Treponema pallidum is abundant in the chancre (painless ulcer). The organism can be demonstrated by dark-field microscopy or PCR.

7. The bacteria can be found in lesions of secondary syphilis.

Correct Answer: ✅ True
Explanation: T. pallidum is present and highly infectious in the mucocutaneous lesions of secondary syphilis (e.g., condylomata lata, mucous patches).

8. The bacteria can be found in the cerebrospinal fluid of tertiary syphilis.

Correct Answer: ✅ True (sometimes)
Explanation: In tertiary syphilis, T. pallidum is rarely seen in lesions, but can be detected in CSF in neurosyphilis cases using PCR or other advanced tests. So this statement is true in the context of neurosyphilis.

9. RPR is specific for Treponema pallidum infection.

Correct Answer: ❌ False
Explanation: RPR (Rapid Plasma Reagin) is a non-treponemal test that detects reagin antibodies to cardiolipin — not specific for T. pallidum.
It may yield false positives in other conditions (e.g., pregnancy, autoimmune diseases).
Specific tests include FTA-ABS and TPHA.

10. It is resistant to Penicillin.

Correct Answer: ❌ False
Explanation: Treponema pallidum remains highly sensitive to penicillin, which is the treatment of choice for all stages of syphilis. No proven resistance has been documented.

OSCE

Question 1

Scenario:
A child presents with generalized absence of pigmentation of the skin, hair, and eyes.

1. What condition does the child have?
Answer: ✅ Albinism
Explanation:
Albinism is a genetic disorder characterized by a deficiency or absence of melanin pigment in the skin, hair, and eyes due to enzyme defects in melanin synthesis.

2. What enzyme deficiency underlies this condition?
Answer: ✅ Tyrosinase deficiency
Explanation:
The key enzyme tyrosinase catalyzes the conversion of tyrosine → DOPA → melanin.
A defect or absence of tyrosinase leads to reduced or absent melanin production, resulting in albinism.

3. List three major complications arising from this condition.
Answers:

• Decreased vision (due to foveal hypoplasia, nystagmus, or photophobia)
  
  

• Skin cancer (especially squamous cell carcinoma and basal cell carcinoma)
  
  

• Premature photoaging of skin (due to chronic UV exposure without melanin protection)
  
  

Explanation:
Melanin protects against UV-induced DNA damage. Its absence predisposes albinos to ocular and cutaneous complications.

4. How would you prevent major complications arising from this condition?
Answers:

• For decreased vision: Use corrective lenses or glasses.
  
  

• For skin cancer and photoaging: Use broad-spectrum sunscreen, UV-protective clothing, hats, and avoid direct sunlight.
  
  

Explanation:
Preventive measures focus on UV protection and regular dermatologic and ophthalmologic evaluations to minimize complications.

✅ Summary:

• Diagnosis: Albinism
  
  

• Enzyme deficiency: Tyrosinase
  
  

• Major complications: Visual defects, skin cancers, photoaging
  
  

• Prevention: UV protection (sunscreens, clothing), eye care (glasses)

Question 2

Scenario:
A patient presents with a firm, raised, shiny overgrowth of scar tissue on the ear following piercing or trauma.

1. What is the diagnosis for the lesion on the ear?
Answer: ✅ Keloid

Explanation:
A keloid is an excessive proliferation of scar tissue that extends beyond the original wound margins due to abnormal wound healing. It commonly occurs on the earlobes, chest, shoulders, and upper back.

2. What is the pathophysiology?
Answers:

• Increased Transforming Growth Factor-beta (TGF-β) expression → stimulates fibroblast proliferation
  
  

• Increased Type I collagen : Type III collagen ratio (excess Type I collagen deposition)
  
  

• Decreased elastin production → reduced tissue flexibility
  
  

Explanation:
Keloids result from prolonged fibroblast activity and excessive collagen synthesis during wound healing, leading to raised, firm, fibrous tissue that continues to grow even after healing is complete.

3. How would you treat this condition?
Answers:

• Intralesional corticosteroid injections (e.g., triamcinolone) – first-line to reduce fibroblast proliferation and collagen deposition
  
  

• Cryotherapy – causes local tissue destruction
  
  

• Surgical excision – may be combined with steroids or pressure dressings to reduce recurrence
  
  

Explanation:
Treatment aims to suppress fibroblast activity and prevent recurrence, as surgical removal alone has a high relapse rate.

4. What is the differential diagnosis with a similar pathophysiology?
Answer: ✅ Hypertrophic scar

Explanation:
Both keloids and hypertrophic scars result from excess collagen deposition.
However:

• Keloids extend beyond the original wound margins and rarely regress.
  
  

• Hypertrophic scars remain confined within the wound boundaries and may regress spontaneously.
  
  

✅ Summary:

• Diagnosis: Keloid
  
  

• Pathophysiology: Excess TGF-β → fibroblast proliferation → excessive collagen
  
  

• Treatment: Intralesional steroids, cryotherapy, surgery with preventive measures
  
  

• Differential: Hypertrophic scar
  
  

Question 3

Scenario:
A young patient presents with multiple comedones, papules, pustules, and occasional cysts on the face.

1. What is the diagnosis?
Answer: ✅ Acne vulgaris

Explanation:
Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit, characterized by comedones (blackheads and whiteheads), papules, pustules, nodules, and cysts.
It commonly affects adolescents due to hormonal stimulation of sebaceous glands.

2. List three factors involved in the pathogenesis of this condition.
Answers:

• Blockage of the pilosebaceous duct (due to hyperkeratinization)
  
  

• Sebaceous gland hyperplasia with increased sebum production
  
  

• Colonization by Propionibacterium acnes (now Cutibacterium acnes)
  
  

• Inflammation within the follicle
  
  

• Altered follicular epithelial growth and differentiation
  
  

Explanation:
The pathogenesis involves:

1. Follicular plugging → obstruction of sebum outflow.
   
   

2. Sebum overproduction under androgen influence.
   
   

3. Bacterial proliferation (C. acnes) within blocked follicles.
   
   

4. Inflammation → formation of pustules and nodules.
   
   

3. List two parts of the body commonly affected, besides the face.
Answers:

• Back
  
  

• Chest
  
  

Explanation:
Acne lesions occur where sebaceous glands are most numerous — face, chest, shoulders, and back.

4. Name one drug or family of drugs that is effective in managing this condition.
Answer: ✅ Retinoids (e.g., Adapalene, Tazarotene, Tretinoin)

Explanation:
Topical retinoids normalize keratinization, reduce follicular plugging, and have anti-inflammatory effects.
Other effective drug classes include:

• Antibiotics (topical or oral: doxycycline, clindamycin)
  
  

• Benzoyl peroxide (antimicrobial and comedolytic)
  
  

• Oral isotretinoin (for severe or cystic acne)
  
  

✅ Summary:

• Diagnosis: Acne vulgaris
  
  

• Pathogenesis: Blocked pilosebaceous duct, excess sebum, C. acnes proliferation, inflammation
  
  

• Sites: Face, chest, back
  
  

• Treatment: Retinoids (adapalene, tazarotene), antibiotics, benzoyl peroxide
  
  

Question 4

Scenario:
A patient presents with a chronic, itchy rash characterized by dry, inflamed, and thickened skin. The condition has a history of flares and remissions, often associated with allergies or asthma.

1. What is the diagnosis for the itchy rash?
Answer: ✅ Atopic Dermatitis (Eczema)

Explanation:
Atopic dermatitis is a chronic, relapsing, pruritic inflammatory skin disorder often associated with a personal or family history of asthma, allergic rhinitis, or atopy.
Typical features include intense itching, xerosis (dry skin), and eczematous lesions that may become lichenified with chronic scratching.

2. What gene may be commonly associated?
Answer: ✅ Filaggrin (FLG) gene mutation

Explanation:
Filaggrin is a skin barrier protein essential for maintaining epidermal integrity and hydration.
Mutations in the FLG gene lead to defective skin barrier function, increased transepidermal water loss, and heightened susceptibility to allergens and irritants — a hallmark of atopic dermatitis.

3. What is the mainstay of management?
Answer: ✅ Petrolatum-based emollients (moisturizers)

Explanation:
Emollients are the cornerstone of therapy; they:

• Restore and maintain skin barrier function
  
  

• Reduce itching and dryness
  
  

• Decrease the need for topical corticosteroids
  Petrolatum-based products are especially effective as occlusive moisturizers, locking in hydration.
  
  

4. How would you treat exacerbations?
Answer: ✅ Systemic or topical corticosteroids (depending on severity)

Explanation:
During flares:

• Topical corticosteroids are first-line for mild to moderate exacerbations.
  
  

• Systemic corticosteroids may be used short-term for severe, widespread cases.
  
  

• Antihistamines and topical calcineurin inhibitors (e.g., tacrolimus) can be added as adjuncts.
  
  

5. What secondary skin lesion may result from chronic scratching?
Answer: ✅ Lichenification

Explanation:
Lichenification is a thickening of the skin with exaggerated skin markings resulting from chronic scratching or rubbing.
It is a classic secondary lesion seen in chronic atopic dermatitis.

✅ Summary:

• Diagnosis: Atopic dermatitis
  
  

• Associated gene: Filaggrin mutation
  
  

• Mainstay of treatment: Petrolatum-based emollients
  
  

• Exacerbation management: Corticosteroids (topical or systemic)
  
  

• Chronic lesion: Lichenification
  
  

Question 5

Scenario

A 15-year-old boy presents to the dermatology clinic with a rough, raised lesion on the back of his right hand. It has been slowly increasing in size over the past few months. The lesion is firm, non-tender, and has a rough, cauliflower-like surface. There are no similar lesions elsewhere, and the patient has no systemic symptoms.

1. What is the diagnosis?

✅ Verruca Vulgaris (Common Wart)

Detailed Explanation:
Verruca vulgaris is a benign epithelial growth caused by infection with human papillomavirus (HPV). It commonly appears on fingers, hands, knees, and elbows, especially in children and young adults. The lesion is hyperkeratotic, rough, and may show black dots (thrombosed capillaries) on close inspection.

2. What are the other types of warts?

✅ Other Types:

• Verruca Plana (Flat wart):
  
  

  • Smooth, flat-topped, flesh-colored papules.
    
    

  • Common on the face, neck, and back of the hands.
    
    

  • Caused mainly by HPV types 3 and 10.
    
    

• Verruca Plantaris (Plantar wart):
  
  

  • Found on the soles of the feet.
    
    

  • Can be painful when walking due to pressure.
    
    

  • Caused by HPV types 1, 2, and 4.
    
    

Detailed Explanation:
Different HPV types infect different areas of the body, giving rise to various clinical forms of warts.

3. What is the causative agent?

✅ Human Papillomavirus (HPV) types 2 and 4

Detailed Explanation:

• Verruca vulgaris is most often caused by HPV types 2 and 4, occasionally types 7 or 27.
  
  

• HPV infects the basal keratinocytes through small skin abrasions and stimulates epidermal hyperplasia (thickening), forming the characteristic wart.
  
  

4. What are the histological features?

✅ Histology of Verruca Vulgaris:

• Epidermal Hyperplasia: Thickened epidermis due to HPV-induced proliferation.
  
  

• Irregular Hyperkeratosis: Overgrowth of keratin layer on the surface.
  
  

• Acanthosis: Thickening of the prickle-cell (stratum spinosum) layer.
  
  

• Papillomatosis: Upward projection of dermal papillae, producing a warty surface.
  
  

• Koilocytosis: Presence of koilocytes — enlarged keratinocytes with perinuclear halos — a hallmark of HPV infection.