A rare cause of small bowel obstruction caused by duodenum-derived aggressive fibromatosis with β-catenin T41A mutation: A case analysis.

Rationale: Aggressive fibromatosis (AF) is a fibroblastic/myofibroblastic tumor known for its locally aggressive properties. Intra-abdominal AF primarily occurs in the small intestine mesentery, ileocolic mesocolon, omentum, retroperitoneum, and pelvis, and rarely originates from the intestinal wall. Here, we report a rare case of small bowel obstruction caused by duodenum-derived AF with β-catenin (CTNNB1) T41A mutation.

Patient Concerns: A 35-year-old male had a 4-month history of abdominal pain, nausea, and vomiting, which gradually worsened over time.

Diagnoses: Based on the results of CT examination, histopathology and Sanger sequencing, the patient was diagnosed with small bowel obstruction caused by duodenum-derived AF.

Interventions: Due to the extensive adhesion between the tumor and surrounding tissue, it is extremely challenging to completely remove the tumor through surgical resection with negative margins in this case. In order not to damage the function of surrounding vital organs, gastrojejunostomy was performed to relieve the symptoms of small bowel obstruction.

Outcomes: The patient experienced a successful recovery. It is important to note that this patient is still at risk of local recurrence and requires regular follow-up.

Lessons: The best treatment should be taken based on the individual patient to relieve symptoms and improve quality of life. Moreover, histopathology plays a crucial role in diagnosing and differentiating duodenum-derived AF. The detection of mutations in exon 3 of the CTNNB1 has become strong evidence for diagnosing duodenum-derived AF.