Abdominal Desmoid Fibromatosis
Definition
- Cytologically bland, at most moderately cellular, deep infiltrative fibroproliferative process involving abdominal wall
Alternate / Historical Names
- Abdominal fibromatosis
- Musculoaponeurotic fibromatosis
- Aggressive fibromatosis
Diagnostic Criteria
- Over age 5 years by definition (see Infantile Fibromatosis)
- Involves fascia and muscle of abdominal wall by definition
- Peripheral infiltration of skeletal muscle is seen in nearly all cases
- Very important diagnostic feature
- Muscle fibers at the periphery show degenerative changes
- Muscle rare in center of lesion
- Lesion centered below level of subcutis
- Subcutis may be involved by large lesions
- May surround nerves
- Low to moderate cellularity
- Bland spindle cells in fascicles or haphazardly arranged
- Nuclei small, dark to slightly enlarged and vesicular
- Cytoplasm scant
- Stroma may be densely collagenous or myxoid
- May be 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
- Gross circumscription may be deceptive
- Nearly always over 3 cm
- Usually 3-7 cm
- Thin walled compressed “slit like” vessels frequent
- Focal hemorrhage may be seen
- Hemosiderin rare
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting: October 15, 2007
Last Update: March 16, 2008
