Pyoderma gangrenosum associated with paroxysmal nocturnal haemoglobinuria

A case of pyoderma gangrenosum of the lip occurring in association with paroxysmal nocturnal haemoglobinuria is described. This is an extremely rare association, which has been documented in the literature on only two previous occasions. Pyoderma gangrenosum (PG) is an uncommon ulcerative skin disorder of unknown aetiology. Its clinical appearance is often distinctive, with established lesions consisting of a necrotic ulcer surrounded by a ragged undermined violaceous edge. Lesions are usually painful and are most often found on the lower limbs but can occur on the trunk, head and neck. The diagnosis is essentially clinical as there are no characteristic histopathological changes. Since its original description in 1930, PG has been frequently associated with a number of underlying systemic diseases. Foremost among these are inflammatory bowel disease and inflammatory polyarthritis. The association with haematological disorders is also well recognized, and includes acute and chronic lymphocytic and myeloid leukaemias, polycythaemia rubra vera, myelofibrosis, myelodysplastic syndrome, essential thrombocythaemia, hypogammaglobinaemia, monoclonal gammopathy, multiple myeloma and non-Hodgkin's lymphoma. We report a case of PG occurring on the lower lip of a 26-year-old man recently diagnosed as having paroxysmal nocturnal haemoglobinuria (PNH).