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Author: Vanessa Ngan, Staff Writer, 2013. Updated by A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, January 2018.
Sebaceous glands are small glands connected to hair follicles in the skin. They are located in any hair-bearing region of the body but are most numerous on the skin of the scalp and face. The glands are responsible for producing sebum which is an oily substance that keeps hair and skin moisturized.
Sebaceous carcinoma is a rare aggressive skin cancer. Sebaceous carcinoma is sometimes called sebaceous gland adenocarcinoma.
Ocular sebaceous carcinomas affect adults. It occurs more frequently in Asian populations than Caucasians and is more common in women than in men, particularly those around 60 to 80 years of age. In patients with a predisposing genetic syndrome, it may be diagnosed at a younger age.
Extraocular sebaceous carcinomas occur mainly in older adults and without predilection for male or female.
The exact cause of sebaceous carcinoma is unclear. The following have been reported to possibly increase the risk of these tumours:
What are the clinical features of sebaceous carcinoma?
Sebaceous carcinoma most commonly develops from the meibomian glands which are located mostly in the upper but also in the lower eyelids. Clinical features of ocular sebaceous carcinoma include:
Extraocular sebaceous carcinoma accounts for about 25% of sebaceous carcinomas. These tumours mostly occur around the head and the neck. Other sites where these tumours have been found include the genitals, ear canal, breasts, trunk and oral cavity.
The clinical presentation of extraocular lesions is non-specific; they typically appear as a pink to a yellow-red nodule of varying sizes.
Sebaceous carcinoma may be suspected clinically. Dermoscopy may reveal typical irregular yellowish lobules and irregular linear blood vessels.
Definitive diagnosis is based upon patient history, adequate surgical biopsy and the combined knowledge of a pathologist, ophthalmologist and dermatologist.
Immunohistochemistry stains may be used to determine the likelihood of an underlying genetic syndrome.
The diagnosis of ocular sebaceous carcinoma is often delayed by months to years (mean delay from disease onset to diagnosis ranges from 1–3 years) because numerous other inflammatory conditions, autoimmune diseases, infectious processes and other tumours mimic the condition.
Note that basal cell carcinoma is less aggressive than sebaceous carcinoma, but sometimes shows sebaceous differentiation.
What are the complications of sebaceous carcinoma?
Sebaceous carcinoma, although rare, is an aggressive and potentially dangerous tumour that can lead to significant morbidity and mortality. The overall mortality rate is 5–10% because of inherent tumour factors, or delayed diagnosis and treatment.
Factors for a poorer prognosis include delay in diagnosis of greater than 6 months, tumour diameter greater than 1 cm, and both upper and lower eyelid involvement.
Radical surgical excision with frozen section control by either a standard method or Mohs micrographic surgery is the most common and effective method of treatment. Approximately, 30% of sebaceous carcinomas recur after resection.
Radiation therapy should only be used in patients unable or willing to undergo surgery.
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