[Causes of pilonidal sinus and pyoderma fistulans sinifica].

Pilonidal sinus is of the same origin as the Pyodermia fistulans sinifica . Both diseases are retention dermatopathies . These sinuses are not of congenital origin. Our observations have made an acquired origin seem more likely. Deep skin folds in the rima ani, the stiffness of the body hairs, the rolling movement of naturally separated hairs push the hair through the skin like a pin. If a hair is rubbed, it moves in the direction of its root with the peripherally directed hair scales. Excision of the sinus area and transplantation of an epithelial flap is the best therapy.