Pyoderma gangrenosum associated with hidradenitis suppurativa.

Pyoderma gangrenosum (PG) is associated with a number of systemic diseases. PG in association with hidradenitis suppurativa (HS) has been rarely reported. We describe six patients (three men, three women; aged 35--51 years), who developed PG on a background of HS. The onset of PG occurred only after HS had been present for at least two decades. No relationship in disease activity between the two conditions was observed. Three patients described previous severe adolescent acne vulgaris, one had concurrent systemic lupus erythematosus and another had chronic iron-deficiency anaemia. The course of PG was severe and refractory in four patients, who required treatment including high-dose oral corticosteroids, ciclosporin, intravenous immunoglobulin and intravenous cyclophosphamide.