[Ulceration of the scalp: a unique manifestation of pyoderma gangrenosum]

Pyoderma gangrenosum is a chronic, noninfectious, ulcerating cutaneous disease of unknown etiology usually presenting with multiple lesions on the legs and trunk. Solitary lesions in other locations are rare and therefore hard to diagnose. A 78-year-old and a 81-year-old woman with extensive scalp necrosis were both diagnosed as pyoderma gangrenosum after exclusion of other differential diagnostic possibilities. The separate diagnosis of malignant pyoderma for this disease state no longer seems justified. Scalp necrosis is infrequently seen in dermatological patients; most previous reports describe it in giant cell arteritis. Other differential diagnoses include viral, bacterial and mycotic infections as well as erosive pustular dermatosis of the scalp. In conclusion, we again draw attention to unilesional pyoderma gangrenosum of the scalp as a rare disease entity. Immunosuppressive drugs are an effective treatment modality.