Spontaneous isolated mesenteric fibromatosis complicated by small bowel perforation: a case report and literature review

Mesenteric fibromatosis (MF) is a mesenteric form of desmoid-type fibromatosis, a locally aggressive fibroblastic neoplasm without metastatic potential. Sporadic isolated MF presenting with acute small bowel perforation is exceptionally rare and poses significant diagnostic challenges. We describe a 48-year-old man with MF and acute jejunal perforation. PubMed/MEDLINE, Embase, Web of Science, and Cochrane Library were searched from inception to April 2026 for English-language case reports of MF presenting with bowel perforation. Data on demographics, clinical presentation, tumor characteristics, immunohistochemistry, treatment, and outcomes were extracted and analyzed. A 48-year-old male with a history of meningioma resection presented with acute epigastric pain. Contrast-enhanced CT revealed a 7.0 × 5.0 × 3.5 cm heterogeneous soft tissue mass in the left upper abdomen with surrounding inflammatory changes and extraluminal air, suggestive of a perforated small bowel tumor. Emergency laparotomy identified a firm mesenteric mass with an adjacent 1.0 cm jejunal perforation. En bloc resection with primary anastomosis was performed. Immunohistochemistry demonstrated nuclear positivity for β-catenin and LEF-1, with negative staining for CD117, DOG-1, and S-100, confirming the diagnosis of sporadic isolated mesenteric fibromatosis. The postoperative course was uneventful, and the patient remained recurrence-free after more than 9 months of follow-up. A literature review identified 9 additional cases. Including our case, 10 patients (8 males, 2 females; mean age 39.1 years, range 18–60) were analyzed. Tumor sizes ranged from 5 to 31 cm (mean 12.8 cm, n = 9). β-catenin positivity was reported in 5 of 6 tested cases (83.3%). Negative microscopic margins were documented in 4 cases, including the index case. Follow-up reporting was heterogeneous and did not permit a reliable estimate of recurrence risk. Sporadic isolated mesenteric fibromatosis should be considered in the differential diagnosis of acute abdominal pain with an associated mass. Nuclear β-catenin immunopositivity is a key diagnostic feature for accurate diagnosis. Complete surgical resection appears to be the preferred approach for symptomatic, resectable lesions in the emergency setting, and close surveillance is recommended given the well-documented risk of local recurrence in the broader literature.