Colocutaneous fistula through ulcerative colitis and cancer to the pyoderma gangrenosum: a never-ending story for a single patient. Case report.

Background: Inflammatory bowel diseases may be associated with many extraintestinal complications, that in some cases can represent the first onset of these disorders. In particular during the course of the disease, Ulcerative Colitis develops extraintestinal manifestations very frequently. One of the rarest is pyoderma gangrenosum, a noninfectious neuthrophilic dermatosis, that can involve most commonly legs but also other parts of the skin or mucosas. It can be idiopathic or associated with gammopathies, vasculitis, chronic arthritis or, like in our case, with inflammatory bowel disease and malignancies.

Case presentation: A 38-year-old man was referred to our Department with a colo-cutaneous fistula in the left quadrant of abdominal wall. In the anamnesis he reported a trauma during a soccer match three weeks before. Through a CT scan and endoscopy with biopsy an inflammatory bowel disease with a segmental colitis and stenosis was diagnosed. After medical therapy, an initial radiological drainage and a period of parenteral nutrition, he underwent a left hemicolectomy. Despite the previous endoscopic biopsy the histopathological examination put in evidence not only inflammatory disease (in particular Ulcerative Colitis) but also a colorectal tumor pT4pN0. After the full recovery before chemotherapy he has developed on the chest and on the abdomen some painful nodules, with central necrosis, one of those in contact with one of the ribs. Through TC and RM it was impossible to understand the precise nature of these skin lesions. With biopsy a pyoderma gangrenosum was diagnosed and treated until complete resolution.

Discussion and conclusion: Management of inflammatory bowel diseases can be a true challenge, not only for the intestinal manifestations, but also for all the other features not related to gut. In some cases the same patient can develop many complications, such as malignancies or rare cutaneous diseases. Despite the initial surprise for such a weird evolution in a same patient, from fistula to inflammatory disease to cancer and finally to pyoderma gangrenosum, to face every single complication following consolidated diagnostic and pathological paths has been the correct strategy for controlling the disease.