Skin Disorders/Rash

General Overview

• Inspect all areas of skin

  • Include scalp, behind ears, back of neck

  • Oral cavity

  • Genital and perineum

  • Nails, palms of hands and soles of feet

  • Intertriginous areas (e.g., axilla, skin folds of the breasts and between digits)

• Biopsy or excision to rule out serious pathology

History

• Previous episodes

• Previous treatment

• Contact/exposure/travel (e.g., infectious, new detergents/fabric softeners/lotions/deodorants, metal belt buckles/glasses, different humidity/climates)

• Medication/drugs (e.g., antibiotics [penicillin, sulfonamides], corticosteroids, NSAIDs, anti-epileptics)

• PMH/family history

• Associated symptoms (pain, pruritus, bleeding, exudate, blistering/ulcerations, fever, aches)

• Occupational history

• Impact on patient's life (function, sleep, mood, social life)

Physical Exam

SCALDA:

• Size/shape/texture: well vs. poorly demarcated, targetoid, verrucous, umbilicated

• Colour: erythematous, violaceous, hyper/hypopigmented, depigmented, jaundiced

• Arrangement: solitary, grouped, linear, reticular/mottled, dermatomal

• Lesion type (primary/secondary):

  • Primary (< 1cm/>1cm) = macule/patch, papule/plaque, nodule/tumour, vesicle/bulla

  • Secondary = lichenification, maceration, erosion/ulceration

• Distribution

• Always look at nails (e.g, pitting, oil spots), hair (e.g., scalp plaques, hair thinning), mucous membranes (e.g., white lacy patches, open sores), intertriginous areas

General Skin Care

• Eliminate exacerbating factors

  • Excessive bathing (without subsequent moisturization)

  • Low humidity environment

  • Overheating/hot water exposure

  • Avoid potential allergens and irritants

    • Exposure to solvents/detergents

    • Avoid fragrant/perfumed topic agent

    • Avoid coarse fiber clothing (wool/synthetic)

  • Emotional stress/anxiety

  • Xerosis (dry skin)

  • Treat skin infections (S. aureus, herpes simplex)

• Sunscreen/protection

• Hydration/Emollients multiple times per day
  💡 Occlusiveness of topical preparations (from most to least): ointments (use for dry lesions) > creams (use for wet lesions) > lotions (use for weeping/intertriginous lesions)

Rule-out life-threatening conditions

• Stevens-Johnson syndrome (<10% skin involved) / Toxic epidermal necrolysis (>30% skin involved)

  • Rare immune-mediated skin reaction, usually triggered by medications

  • Prodromal flu-like illness: Fever >39C, sore throat, rhinorrhea, cough, aches

  • Sudden onset tender/painful skin rash on face/limbs, 90% with involvement of mucous membranes (mouth, eyes, genital)

    • Tender red/purple macules, diffuse erythema, targetoid lesions, bullae and/or vesicles (may have positive Nikolsky)

  • Treat aggressively

    • Treat underlying trigger

      • Stop causative drug (commonly allopurinol, NSAIDs, antibiotics, antiepileptics)

      • Treat infections (eg. Mycoplasma pneumoniae)

    • Admission to ICU

    • IV fluid resuscitation and wound management

• Necrotizing soft tissue infections (cellulitis, fasciitis, myositis, gas gangrene)

  • Mortality rate 20-80%

  • Diffuse erythema, swelling, warmth, shiny, exquisite tenderness

    • Late findings include crepitus, bullae, skin necrosis, loss of sensation

  • ↑ WBC, ↑ CRP/ESR, ↑ CK, subcutaneous air on XR/CT/MRI

  • ICU admission plus aggressive surgical exploration and debridement and broad-spectrum antibiotics: e.g., Tazo/Clinda/Vanco IV

• Meningococcal infection

  • Can present with abnormal skin color pallor, mottling

  • Petechial rash involving trunk, lower body, mucous membranes (oral and ocular), may have purpura, ecchymotic lesions

• Chemical or non-chemical burns

💡 When in doubt, consult Poison Control for additional guidance

• Fluid Resuscitation for burns >15% BSA in children and >20% BSA in adults

  • Modified Brooke/Parkland Formula 2-4mL x %BSA x kg Ringer's Lactate, 1/2 in first 8 hours, 1/2 in next 16 hours

• Wound management

  • Keep moist

  • Apply antibiotic ointment to non-adherent dressing (Adaptic) then apply to wound

  • Pain control

  • Ensure tetanus vaccine status up-to-date

• Follow-up at <72h, to re-assess burn to better characterize partial vs. full thickness

• • Refer to burn center PRN

Rule-out serious pathology

• Malignancy

  • Melanoma

    • ABCDE (Asymmetry, Border, Colour, Diameter >6mm, Evolving/elevation)

    • Subtype frequency: superficial spreading > nodular > lentigo maligna > acral lentiginous

    • Diagnosis and treatment: full-thickness excisional biopsy with 0.5-2cm safety margin (according to Breslow thickness)

      • Prognosis highly dependent on Breslow thickness, 5-year survival drops with depth > 1-2 mm

• Basal Cell Carcinoma

  • Nodular BCC (most common) - raised pearly white nodule with telangiectasia >6mm

  • Superficial BCC - red scaling plaques with thready border

  • Diagnosis and treatment: full or partial-thickness biopsy (at edge of lesion to contain normal tissue)

  • Excellent prognosis (low rates of malignancy)

• Squamous Cell Carcinoma

  • Persistent ulceration, crusting, hyperkeratosis, erythema

  • Treatment: Surgical excision + biopsy (e.g., punch biopsy, Mohs micrographic)

  • SCC In Situ: Bowen's disease

  • Pre-malignancy: Actinic keratosis (AK), Leukoplakia (oral)

    • Treat local AK with cryotherapy (eg. two freeze thaw cycles of 5s)

    • Treat widespread AK with fluorouracil 5% cream BID x 2-6 weeks

• Cutaneous T-cell lymphoma (Mycosis Fungoides)

  • Lymphocyte infiltration in progressive stages (slow course over years)

  • Pruritus → oval or annular patches → thickened plaque → tumors

• Pemphigus

💡 Not to be confused with the more common and less severe Pemphigoid blistering diseases (e.g., bullous pemphigoid)

• Refers to a group of life-threatening autoimmune blistering and erosive diseases affecting the skin and mucosa (

  • Complications include infection, fluid loss, electrolyte disturbances

• Types: Vulgaris (most common; 70% of all pemphigus), Foliaceus, IgA, Paraneoplastic

  • Treatment

    • Systemic steroids (1-2mg/kg prednisone daily or 0.5-1mg/kg in combination with rituximab)

      • Azathioprine or mycophenolate mofetil are often used to attempt to reduce steroids

      • Consider adjunctive high potency topical steroid (e.g., clobetasol propionate) for larger erosions

    • Cover erosions with antibiotic ointment or a bland emollient (eg, petroleum jelly) +/- non-adhesive wound dressings

Rule-out systemic disease

• Granulomatosis with polyangiitis (Wegener’s)

  • Purpura in lower extremities, focal necrosis and ulcerations (may also include urticaria, livedo reticularis, nodules)

• Systemic lupus erythematosus (SLE)

  • Acute

    • Malar (or butterfly) rash that resolves without scarring

    • Bullous, maculopapular, mucosal erosions/ulcerations, photosensitivity, hair loss

  • Subacute

    • Flat scaly patches, annular polycyclic lesions on trunk and arms

  • Chronic

    • Indurated hyperpigmented discoid plaques (most above neck)

• Diabetes

  • Acanthosis nigricans (seen in most patients with childhood diabetes)

  • Diabetic dermopathy (30% of patients with diabetes)

    • Light brown/red oval/round scaly patches usually in pretibial area

• Celiac

  • Dermatitis Herpetiformis ("Celiac of the skin")

    • Pruritic papulovesicular rash on extensor

    • Can biopsy to confirm celiac

  • Recurrent aphthous stomatitis

• Drug reaction

  • Morbilliform/exanthematous drug eruption

  • Urticaria/angioedema

  • Severe cutaneous adverse reactions include drug hypersensitivity syndrome, SJS/TEN

  • Treat

    • Stop responsible drug

    • Emollients frequently

    • Topical corticosteroids (consider systemic if severe)

    • Antihistamines for urticaria

• Kaposi's Sarcoma

  • Common in AIDS and following organ transplant

  • Purple/black papular lesions, most commonly affecting lower limbs, back, face, mouth, genitalia