Mesenteric Fibromatosis
Definition
- Cytologically bland, at most moderately cellular, deep infiltrative fibroproliferative process primarily involving mesentery or other intra-abdominal sites
Alternate / Historical Names
- Intra-abdominal fibromatosis
- Musculoaponeurotic fibromatosis
- Aggressive fibromatosis
Diagnostic Criteria
- Over age 5 years by definition
- Essentially the same as abdominal desmoid fibromatosis except for location, positive association with polyposis, lack of association with pregnancy and more diffuse myxoid stroma in some cases
- Primarily based in mesentery by definition
- If retroperitoneum involved by extension from mesentery, lesion should be considered mesenteric fibromatosis
- Peripheral infiltration of bowel wall muscularis may be seen
- Low to moderate cellularity
- Bland spindle cells in fascicles or haphazard
- Nuclei small, dark to slightly enlarged and vesicular
- Cytoplasm scant
- Stroma may be densely collagenous or myxoid
- May have keloid like fibers
- Rare metaplastic cartilage and bone
- Mitotic figures infrequent
- Rarely >5 per HPF
- Never atypical
- Inflammation not prominent
- May be seen focally, usually peripherally
- Prominent thin walled dilated veins and thick walled muscular arteries
- Gross circumscription may be deceptive
- Nearly always over 3 cm
- Average 15 cm
- Focal hemorrhage may be seen
- Hemosiderin rare
- May be associated with familial adenomatous polyposis / Gardner syndrome, see Clinical at left
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 10/15/07, 12/22/08, 2/8/09, 12/12/09
