Sebaceous adenitis

What is sebaceous adenitis?

Sebeceous adenitis is a skin disease in which inflammation of sebaceous glands is found on histopathological examination of the affected skin.

Sebaceous adenitis has rarely been described on the face in males and females and on the vulva of women. It has been more commonly described in dogs, which present with quite different symptoms – dandruff and hair loss.

What are sebaceous glands?

Sebaceous glands secrete sebum, an oily substance, to lubricate the skin and hair. This helps waterproof the skin and protect it from drying out and from infection. The greatest number of sebaceous glands is found on the scalp and face. There are none on the palms and soles. Sebaceous glands are most active before birth and after puberty, continuing to excrete sebum until menopause in women and throughout adult life in men.

Sebaceous glands usually drain into the hair follicle. Sebaceous glands in hairless skin (eg eyelids, lips, nipples, penis and vulva) drain directly onto the skin surface.

What causes sebaceous adenitis?

The exact cause of sebaceous adenitis is not known. The following may play a role in its development:

• Sun exposure (facial rash)
• Hormones (females with vulval lesions)
• Innate immune system (non-allergic inflammation)

Sebaceous adenitis in canines is autoimmune in origin, and may be hereditary.

Infection has not been shown to cause sebaceous adenitis.

What are the signs and symptoms of sebaceous adenitis?

Facial sebaceous adenitis

Facial sebaceous adenitis has been described as an asymptomatic, recurrent, erythematous (red), annular (ring-shaped) rash affecting males and females.

Vulval sebaceous adenitis

Vulval sebaceous adenitis is characterised by recurrent tender papules or nodules on the mucosal aspect of the labia minora – these are the hairless inner lips of the vulva of women. Pus may be expressed from the papules. Sebaceous adenitis occurs afer puberty and lesions may recur for years.

How is sebaceous adenitis diagnosed?

The diagnosis may be suspected clinically in a typical case with negative culture of bacterial and viral swabs. Vulval sebaceous adenitis should be distinguished from hidradenitis suppurativa (on hair-bearing skin), inflamed Bartholin cyst and genital Crohn disease.

Biopsy of a papule shows an inflammatory infiltrate around and within sebaceous glands. There may be focal necrosis (death) of sebocytes (the cells that produce sebum).

What is the treatment for sebaceous adenitis?

As the disorder has rarely been described, the best treatment is uncertain. Sebaceous adenitis may recur when treatment is stopped. The following treatments have used in reported cases.

Facial sebaceous adenitis

• Sun protection
• Topical steroids
• Antibiotics
• Hydroxychloroquine

Vulval sebaceous adenitis

• Hormonal treatment using spironolactone and/or ethinyl oestrodiol/cyproterone acetate
• Topical antibiotics eg clindamycin
• Oral antibiotics eg doxycycline