Pyoderma gangrenosum associated with primary thrombocythaemia.

Pyoderma gangrenosum is most commonly associated with inflammatory bowel disease and rheumatoid arthritis, but it has been associated with various haematological malignancies. A 54-year-old man with no history of bowel disease or arthritis presented with a leg ulcer, which healed after treatment. Results of bone marrow aspiration were compatible with primary thrombocythaemia. Seven weeks later there were pronounced recurrence of the ulceration and pyoderma gangrenosum was diagnosed. The appearance of pyoderma gangrenosum associated with blood disorders may differ from that associated with bowel and joint disease.