[A non-infectious pyodermatitis: Pyoderma gangrenosum]

Pyoderma gangrenosum (PG) is a rare chronic inflammatory skin disease characterized by the recurring development of necrotizing and painful ulcers. The skin lesions appear spontaneously or after minor traumatic injuries. Sites of predilection include the lower limbs and the trunk but any part of the body may be affected. PG is not an infectious disease; although the etiology is not completely understood, an immune disturbance is certainly involved. An underlying systemic disorder is associated in up to 50% of the cases, specially inflammatory bowel diseases, arthritis, paraproteinemias and hematologic malignancies. Chronic venous or arterial ulcers as well as bacterial gangrene are the most frequent false diagnoses. A right diagnosis, based upon the distinctive clinical features and a compatible histology, is essential to avoid surgical procedure that often tends to exacerbed the process. Because of its persistent and recurrent nature, systemic long-term therapy based upon corticosteroids associated with sulfones or immunosuppressive agents is required.