Sebaceous glands are simple or branched alveolar organs in the skin, especially where hair is concentrated (eg, sebaceous glands are absent from the palms). The duct for each gland usually opens into the sheath of a hair follicle, although it may open directly on the surface of the skin. A sebaceous cyst is a closed sac under the skin that presents as a small lump. It forms when the sebaceous gland’s secretions accumulate and occlude the duct and can occur at any age. It is usually painless, but may become inflamed and tender. While most sebaceous cysts are benign, if they become infected, necrotizing fasciitis may ensue, but it is rare. About 3% of sebaceous cysts become malignant. There are multiple synonymous terms used to identify the sebaceous cyst. Other names included epidermal inclusion cyst, wen, steatoma and epidermoid cyst. Some authors identify the sebaceous cyst as a separate and distinct lesion because its cells secret sebcum into the cyst while the invaginated epidermis of the epidermoid cyst fills the lesion with layers of keratin. Clinically the epidermoid cyst is typically a firm (almost hard) white small mass which can have layers like an onion when cut. The sebaceous cyst is filled with a liquid or pasty sometimes foul-smelling material (sebcum). In a practical sense probably, these lesions represent a continuum that all related to congenitally or traumatically invaginated epidermis.1,2,3,4
Pathophysiology
Related Anatomy
Differential Diagnosis
Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208
The patient may have been aware of a small, painless lump just under the skin for many years and not mentioned it. On presentation, the patient will likely complain of increased size, discharge, and/or inflammation. Large, disfiguring cysts or locations that interfere with function are common complaints.
SURGICAL COMPLICATIONS:
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