A rare case of solitary colonic fibromatosis mimicking a cystic tumour

Mesenteric fibromatosis or intrabdominal desmoid tumour is a rare proliferative disease that frequently involves the gastrointestinal tract. These tumours account for less than 3% of all tumours among soft tissue neoplasms. Most such lesions are large (10cm or more in diameter) at the time of the excision. Although grossly well-circumscribed, they lesions typically infiltrate the surrounding soft tissues including the bowel wall. The case described here concerns a 62-year-old woman with a partly cystic mesenteric fibromatosis incorporating the large bowel wall, which degenerated into an abscess. A right colectomy was undertaken, and the sample was sent for histological examination. Based on the morphological and immunohistochemical findings, a diagnosis of abdominal fibromatosis was established. The surgical margins were free of disease, and the examined lymph nodes showed cortical hyperplasia and histiocytosis of the lymph sinuses. The patient recovered from surgery with no complications; her fever subsided, and she was discharged from hospital 12 days later. Surgery is the primary therapy for extra-abdominal and intra-abdominal desmoid tumours. Considering the unique biology of desmoid tumours, conservative treatment strategies merit further investigation in both unresectable primary disease and resectable disease. The optimal criteria for choosing surgical or non-surgical treatment still need further evaluation with randomized controlled studies.