Sebaceous Cyst

On examination:

· A globular soft cystic swelling is found on the left side of the face.

· Surface is smooth and margins are well defined.

· There is a punctum on the surface of the swelling and the skin is tethered to the swelling.

· Sometimes greyish cheesy material is seen coming out from punctum with offensive smell.

· The swelling can be indented by pressure.

· Transillumination is negative.

· In big cyst fluctuation may be positive.

What is your diagnosis?

· This is a case of sebaceous cyst on left side of face.

Differential diagnosis?

· Lipoma

· Fibroma

· Neurofibroma

· Dermoid cyst

What is sebaceous cyst?

· This is a retention cyst in relation to sebaceous gland due to blockage of sebaceous duct and accumulation of secretion within the gland.

Where are sebaceous glands located?

· The sebaceous glands are situated in the dermis and their ducts open either into a hair follicle or directly on to the skin surface and it secretes sebum.

In which region sebaceous glands are absent?

· Sebaceous glands are present throughout the body except in palms and soles.

Why it is also called an epidermoid cyst?

· The sebaceous cyst is lined by superficial squamous epithelial cells. So it is called an epidermoid cyst.

What is the content of a sebaceous cyst?

· The sebaceous cyst contains epithelial debris, greyish whitish cheesy material with an unpleasant smell.

Where do you find sebaceous cyst commonly?

· The sebaceous cyst is commonly found in scalp, face, neck, scrotum, chest, breast and shoulder regions.

What organism may be found in sebaceous cyst?

· An organism called Demodex folliculorum may be found in the wall of the sebaceous cyst.

How will you treat this patient?

· Blood sugar examination.

· I will do excision of the cyst under local anaesthesia.

How will you excise the swelling?

· Local anaesthesia by injection of 1% Lignocaine hydrochloride. The local anaesthetic is injected by ring block technique.

· An elliptical incision is made over the swelling keeping a rim of skin around the punctum. The skin flaps are dissected off from the cyst wall. The cyst along with the rim of skin is dissected free from the underlying subcutaneous tissue and the cyst is removed intact along with its lining wall.

What is the other technique of excision of sebaceous cyst?

· It can be excised by incision and avulsion.

· Under local anaesthesia an incision is made over the skin.

· The cyst content is squeezed out.

· The cyst wall is then held up with a forceps and removed by avulsion.

What are the complications of sebaceous cyst?

· Infection

· Ulceration

· Cock’s peculiar tumour

· Sebaceous horn formation

· Rarely malignant change may occur. Usually a basal cell carcinoma.

What are the features of infected sebaceous cyst?

· Patient complains of pain over the swelling and there is recent increase in size of the swelling.

· On examination the overlying skin is red, inflamed.

· The cyst is tender, and on squeezing the cyst pus may be expressed through the punctum.

How will you treat an infected sebaceous cyst?

· Antibiotics.

· After the infection is controlled – excision of the cyst.

· If pus is already pointing, in addition to antibiotics, incision and drainage of pus and avulsion of cyst wall is necessary.

What is Cock’s peculiar tumour?

· This is a complication found commonly in sebaceous cyst of scalp.

· There is infection in the cyst and there is ulceration on the surface of the sebaceous cyst.

· There is escape of cyst content on the surface through the ulcer on the cyst wall.

· Chronic irritation may lead to formation of a granuloma on the surface of the sebaceous cyst.

· This may mimic an epithelioma.

· This appearance of the cyst is called a Cock’s peculiar tumour of scalp.

What is sebaceous horn?

· The sebaceous material may escape through the punctum and accumulate on the surface of the sebaceous cyst and gets dried in successive layers and from a horny projection on the surface of the sebaceous cyst.

· This appearance is called a sebaceous horn.

How will you differentiate a scalp dermoid from a sebaceous cyst?

What are the characteristics of scrotal sebaceous cyst?

· Usually multiple

· May feel solid

· No punctum is usually seen.

How will you treat scrotal sebaceous cyst?

· Single cyst – excision.

· Multiple cysts confined to one segment of the scrotum – excision of that segment of scrotal skin along with the cyst.

· Multiple cyst involving whole of scrotum – Total scrotectomy with all the cyst.

· Testes may be implanted in a subcutaneous tunnel on the medial aspect of the thigh.