Intra-abdominal Desmoid-Type Fibromatosis (Mesenteric Fibromatosis)
The tumor you are describing is called desmoid-type fibromatosis (also known as aggressive fibromatosis), and when located in the abdomen, it is specifically termed mesenteric fibromatosis or intra-abdominal desmoid tumor. 1
Key Characteristics
Desmoid tumors are benign fibroblastic neoplasms that lack metastatic potential but exhibit locally aggressive behavior with infiltrative growth patterns. 1 They account for less than 3% of all soft tissue tumors but are notorious for their unpredictable natural history. 2
Defining Features of Intra-abdominal Desmoids:
- Locally aggressive infiltration into adjacent structures including bowel, mesentery, and retroperitoneal organs 2, 3, 4
- High recurrence rates after incomplete surgical resection, with the tumor demonstrating accelerated growth following surgical manipulation 1, 3
- No metastatic potential, distinguishing them from malignant sarcomas 1, 3
- Unpredictable behavior with possibilities including stable disease, spontaneous regression, or progressive rapid growth 1
Clinical Presentation
Intra-abdominal desmoids most commonly arise from the small intestinal mesentery and can grow to massive sizes (cases reported up to 30×40 cm). 3, 4 They may cause:
- Bowel obstruction or perforation 2
- Mass effect on surrounding organs 4
- Abdominal distension and pressure 4
- Life-threatening complications requiring emergency intervention 1, 2
Molecular Characteristics
Most sporadic desmoid tumors harbor mutations in CTNNB1 (β-catenin gene), while those associated with familial adenomatous polyposis (FAP) or Gardner syndrome have germline APC mutations. 1 CTNNB1 mutation analysis should be part of routine diagnostic workup to identify patients who need evaluation for FAP. 1
Critical Management Principle
The phenomenon of accelerated growth after incomplete resection is well-documented and represents a major clinical challenge. 3 This is why current guidelines emphasize:
- Initial active surveillance (watchful waiting) as first-line management rather than immediate surgery 1, 5, 6
- Surgery reserved only for life-threatening complications or when medical therapy fails 1, 5
- Complete en-bloc resection with negative margins when surgery is performed, as incomplete resection leads to high recurrence rates and potentially more aggressive regrowth 1, 3
The term "mesenteric fibromatosis" is used when these tumors specifically arise from the mesentery, which requires careful monitoring as they can be life-threatening. 1