Follicular occlusion syndrome

What is follicular occlusion syndrome?

The follicular occlusion syndrome refers to a group of diseases in which hair follicles become blocked with keratin (scale) and then rupture, resulting in inflammatory skin disease. These conditions commonly coexist. They may be severe and difficult to treat.

Three of these diseases are together known as the follicular occlusion triad.

• Hidradenitis suppurativa (acne inversa)
• Acne conglobata (severe nodulocystic acne)
• Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens)

A fourth condition, pilonidal sinus or pilonidal disease, makes up the follicular occlusion tetrad.

Follicular occlusion triad

Hidradenitis suppurativa

Acne conglobata

Dissecting cellulitis

What causes the follicles to block?

The precise cause or causes are unknown. There are genetic, hormonal and environmental influences. Environmental factors may include smoking, obesity, humidity and bacteria.

The open comedone is a follicle plugged by dead skin cells. Rupture of the follicle wall results in inflammation, i.e., nodules, ulceration and abscesses. Longstanding inflammation results in scarring.

Follicular occlusion tetrad

Plugged follicles forming comedones

Hidradenitis nodule

Ulceration, sinuses & scars

Hidradenitis suppurativa

Hidradenitis suppurativa is increasing referred to by the name acne inversa. It is a chronic inflammatory skin condition in which there are painful boil-like lumps and draining sinus tracts that leave unsightly scars. It affects the armpits, groin, genitals, buttocks and skin under the breasts.

Hidradenitis suppurativa is three times as common in women as in men; it most affects tehm between puberty and menopause. Follicles are more likely to block up under the influence of hormones, especially the male type (androgens), which are prevalent during this time of life. The circulating levels of hormones are however normal in most affected women. Hidradenitis suppurativa is much more common in smokers than non-smokers, and is also more common in the obese compared to those of normal weight.

Treatment involves various antiseptics and antibiotics, retinoids such as acitretin and isotretinoin, antiandrogens, systemic corticosteroids and surgery.

Acne conglobata

Acne conglobata is an uncommon and unpleasant form of nodulocystic acne in which there are interconnecting abscesses and sinuses, which result in unsightly hypertrophic (thick) and atrophic (thin) acne scars. There are groups of large macrocomedones and cysts that are filled with smelly pus.

Treatment involves prolonged courses of tetracycline antibiotics, oral isotretinoin, and sometimes, systemic corticosteroids.

Dissecting cellulitis

Dissecting cellulitis or folliculitis is also known as perifolliculitis capitis abscedens et suffodiens. It is a rare and severe form of scalp folliculitis.

Large nodules and cysts accompany smaller follicular papules and pustules, from which purulent material can be expressed. Temporary hair loss over the lesions eventually results in permanent scarring and bald patches.

This condition is very resistant to treatment. The severity may be reduced with oral isotretinoin, antibiotics, dapsone and injected or systemic steroids.

Pilonidal sinus

Pilonidal sinus is a dimple or tract found at the base of the spine. A cavity fills up with skin cells and hair shafts. A non-inflamed lump is known as a pilonidal cyst. If the sinus becomes infected a painful pilonidal abscess may form.

Pilonidal disease is 2-3 times more common in men than women. It is more common in obesity and in those with coarse hair.

Treatment may not be needed in mild cases. Antibiotics and surgery are required for chronically inflamed pilonidal disease or abscesses.