Finasteride as a therapy for hidradenitis suppurativa

S IR, Hidradenitis suppurativa is a distressing, androgen‐dependent condition of apocrine sweat gland‐bearing skin characterized by chronic inflammation, mucopurulent discharge and scarring. Although levels of circulating androgens may be abnormal in some patients, in others no obvious abnormality of hormone levels can be detected, suggesting that abnormalities in end‐organ sensitivity may play a part. 1 Although treatment with the antiandrogen cyproterone acetate in combination with oestrogen has been shown to be of some benefit, 2 there are many patients who fail to respond to this, and lack of an effective pharmacological therapy means patients often require deforming surgery. It is known that the normal apocrine gland contains 5‐α reductase which converts testosterone to the potent androgen dihydrotestosterone. Finasteride (Proscar®, Merck Sharp & Dohme, Hoddesdon, U.K.) is a competitive inhibitor of the 5‐α reductase type II isoenzyme, and in multicentre trials it has been demonstrated to be a safe and well‐tolerated treatment for androgenetic alopecia in men. Its main side‐effect is impaired androgenization of the male foetus and, for this reason, it is contra‐indicated in women of child‐bearing age. We report the beneficial use of finasteride in two patients with severe, long‐standing hidradenitis suppurativa. A 56‐year‐old man had suffered severe perianal involvement for 10 years, requiring several courses of antibiotics, a 6‐month course of isotretinoin and extensive surgical resection of the involved area. After 1 month of finasteride 5 mg/day, he reported significant improvement in his symptoms, with reduced frequency of new lesions and reduced exudate. He reported that his symptoms were the best they had been for 10 years, and the benefit has continued for the 9 months that he has remained on finasteride. The second patient was a postmenopausal 55‐year‐old woman with insulin‐dependent diabetes, who had developed hidradenitis suppurativa in adolescence, involving the groins and axillae. She had previously received intermittent courses of antibiotics, had required surgical incision and drainage, and had failed to respond to cyproterone acetate. Finasteride 5 mg/day was well tolerated, with no significant adverse effects. After 3 months, she reported that no new boils had developed and that there had been an improvement in the existing lesions. These initial cases suggest that finasteride may be beneficial in hidradenitis suppurativa, and in view of the previous persistent and very recalcitrant nature of our patients’ symptoms and signs, we are currently extending this study and examining biopsies of involved and uninvolved sites of more patients with hidradenitis suppurativa to determine whether expression of 5‐α reductase type I or type II is occurring in this condition.