Superficial Myofibroblastoma

Definition

Mammary Type Myofibroblastoma is a circumscribed soft tissue tumor frequently containing fat, lacking Rb expression
Intranodal Palisaded Myofibroblastoma is an intranodal tumor with increased beta-catenin expression
Superficial Myofibroblastoma is a superficial lesion that is that does not involve fat and is restricted to the external female reproductive tract

Restricted to external female genital tract
- Vagina, cervix, vulva
Superficial circumscribed
- No capsule
- Frequent grenz zone between lesion and epithelium
- No entrapped fat
Uniform bland stellate and spindled cells
- Oval, elongate nucleus, frequently wavy
- Even chromatin
- Small nucleolus
- 2/26 cases with a few multinucleated cells
- 4/26 cases with mild pleomorphism
Variable patterns of cellularity
- Moderately to highly cellular overall
- Densely collagenous foci with vague fascicles
- Myxoid foci
- Lace-like or sieve-like pattern
  - Cells surround nodules of collagen or myxoid stroma
Mean age 55 years
- Only 2 of 26 cases under age 38

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342