Fox-Fordyce disease

The apocrine sweat glands are located in the armpits, areola, pubis and external genital organs. Their excretory duct empties into the follicular infundibulum above that of the sebaceous gland. The intra-dermal portion of the apocrine duct becomes blocked, preventing release of sweat and sometimes causing a discrete local inflammatory reaction which is the source of the papular rash described by G. H. Fox and J. A. Fordyce in 1902. The pathogenesis of this apocrine miliaria has not been fully elucidated and the mechanisms leading to follicular obstruction are not yet understood.

Fox-Fordyce disease presents as a scattering of small, extremely itchy, slightly translucent or normal flesh-coloured follicular papules clustered preferentially in the areas where apocrine glands are found. Itching and the chronic nature of the condition often cause changes in the surrounding skin, which may become darker and lichenified. It mainly affects younger women (90 percent of cases) and flares up, sometimes by stress or menstrual cycles, suggesting the condition is determined by the intervention of endocrine factors. The differential diagnoses are lichen planus and, above all, acanthosis nigricans.

1 - MEDICAL TREATMENT

There are no universally curative treatments for this harmless condition. However, it is important to address the functional impairment it may cause.

Short courses of class II dermal corticosteroids may be prescribed to reduce itching. Caution must be exercised when applying these creams to the axillary area owing to the risk of secondary infection induced by maceration and constant scratching. They may also be used with acid vitamin A-based products on an occasional basis.

A propylene glycol alcohol solution containing topical clindamycin has also been used successfully in a few cases, but the effects observed are certainly due to the keratolytic potential of propylene glycol.

The rare, extensive forms in men may justify attempting treatment with oral retinoids.

The combined contraceptive pill may improve the symptoms and signs. How exactly this works is not known, but it is used on the basis of clinical arguments, i.e. improvement observed during pregnancy, menstrual-cycle linked exacerbation, post-pubertal onset and disappearance at menopause.

2 - SURGICAL TREATMENT

In exceptional cases, surgery may be proposed after medical treatments have failed ; the subcutaneous fat is removed (potentially preserving the skin) along with the apocrine glands which are mainly located in the deep dermis and hypodermis. When the breast is affected, the technique involves dermal detachment of the areola, then excision of the underlying apocrine sweat glands followed by replacement of the areola and nipple.