M 65, scalp, pigmented mass.
- Well-circumscribed unencapsulated nodular tumor is located in the dermis extending into the subcutis with overlying intact epidermis.
- Tumor is composed of variably sized solid and focally cystic epithelial nodules. Cells are dark, basophilic with dark nuclei like that of basal cell carcinoma.
- Focal peripheral nuclear palisading is present but no artefactual retraction is noted.
- Variety of pattern is noted in different part of the tumor including adamantinoma-like pattern, cribriform-adenoid pattern, and area of heavy melanin pigmentation.
- Overall picture is that of a benign trichogenic tumor, commonly called trichoblastoma.
- Simple excision is curative.
Deba P Sarma, MD