Trichoblastic fibroma.

We report a trichoblastic fibroma in the groin of a 60-year-old woman. This unusual tumor showed a predominance of epithelial component, with abundant basophilic, well-circumscribed, epithelial lobules and some keratinous cysts. Several areas suggested stromal induction of differentiation, and in the keratinous cysts there were indications of outer hair sheath differentiation. We review the clinical data from published cases of trichogenic hair germ tumors and discuss the differential diagnosis.