Inclusion Body Fibromatosis (Infantile Digital Fibroma)
Definition
- Fibrous and spindle cell lesion primarily of digits of infants, characterized by intracytoplasmic eosinophilic inclusions
Alternate/Historical Names
- Infantile digital fibromatosis
- Recurring digital fibroma
- Reye tumor
Diagnostic Criteria
- Nearly always under 1 year of age
- May be congenital
- Rare lesions reported in adults
- Vast majority on 3rd, 4th or 5th digits of hands and feet
- Rare lesions reported in other sites
- May be multiple
- May involve dermis and subcutis
- Poorly circumscribed
- May entrap and surround skin adnexae
- Cellular lesion with bundles of spindle cells
- Vesicular nuclei
- Fibrotic stroma
- Perinuclear round eosinophilic inclusions
- Vary from rare to frequent
- Approximately size of erythrocytes (3-15 mcrons)
- Red on trichrome stain
- Black on iron hematoxylin stain
- Negative on PAS and Alcian blue stains
- Similar bodies have been reported in breast phyllodes and fibroepithelial tumors
- Mitotic figures may be present but not atypical
- Virtually always under 2 cm
- Range 0.3-3.5 cm
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates : 1/11/07, 3/2/08, 1/20/09, 1/29/12
