[Hyperandrogenism and pilosebaceous follicles]

The characteristic of skin is that it is both a site of the metabolism and the target-organ of the androgens which it receives or produces. In the skin, so called "weak" androgens are transformed into more powerful ones, such as androstenedione, testosterone and 5 alpha-dihydrotestosterone. Hyperandrogeny is often found in association with the three main androgenodependent dermatoses: acne, androgenic alopecia and hirsutism. However, the problem of the receptivity of the target-organ, the pilosebaceous follicle, is highlighted in diseases without symptoms of hyperandrogeny. The androgen receptors have been identified in the basal cells of the sebaceous gland and in the hair shaft. The presence of androgen receptors in the keratinocytes and in the cutaneous fibroblasts arises the problem, unresolved to date, of the interactions between the different cutaneous structures.