Giant intra-abdominal desmoid-type fibromatosis infiltrating into the pancreas

Abstract: Intra-abdominal desmoid-type fibromatosis is a proliferative fibroblastic lesion that constitutes 8% of all desmoid tumors and 0.03% of all neoplasm. It is histologically benign with a local aggressive nature and recurs even after excision. It can occur sporadically and or associated with familial adenomatous polyposis mutation. The present case is a 25-year-old female admitted with a chief complaint of abdominal mass gradually increasing in size in the last 6 months. Ultrasound of the whole abdomen initially suggested it to be a uterine/ovarian mass, which is further detailed by the contrast-enhanced computerized tomography (CT) scan. The CT scan showed a large heterodense intraperitoneal mass lesion measuring 34 cm × 25 cm × 16 cm with foci of calcification and necrosis. The mass extended superomedially. It displaced and compressed the stomach wall. It was abutting the peritoneum and was associated with diffuse peritoneal thickening anterolaterally. Posteriorly it was abutting small bowel loops and inferiorly extending into the pelvis and compressing the urinary bladder wall. Posterosuperiorly seems to abut the left kidney and spleen. Desmoid tumor and gastrointestinal stromal tumor (GIST) remained as differentials radiologically and then the patient underwent laparotomy. Histology and immunohistochemistry confirmed it to be fibromatosis. It is, therefore, justified to describe the tumor by considering its rarity, difficulties in diagnosis, and therapeutic ambit.