RESUMEN
Pyoderma gangrenosum (PG) is a rare non-infectious neutrophilic dermatosis often unknowed. It usually presents with inflammatory skin ulcer, very painful, with rapid evolution. It is commonly found in a context of malignancy, inflammatory bowel disease, rheumatic and/or haematological disease. Its diagnosis is very often late after multiple therapeutic failures. We report a case of pyoderma gangrenosum whose diagnosis was not obvious. A patient was admitted to our department for a persistent dermatological lesion and adverse evolution despite debridements and the administration of antibiotics. He was followed for prostate cancer, high blood pressure and asthma. Due to observed biological abnormalities such as neutrophil leukocytosis with myelocyte and metamyelocyte myeloma, without blood blastosis and normochromic normocytic anemia, chronic myelogenous leukemia was suspected. It was later overturned by the various inconclusive supplementary examinations. This is how the diagnosis of PG was evoked and confirmed by anatomopathological examination showing a histopathological appearance of granulation tissue consistent with pyoderma gangrenosum and no sign of malignancy. The institution of a corticotherapy treatment resulted in the cure.