M 65, scalp, pigmented mass.

Diagnosis:  Trichoblastoma

Comment:

  • 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

Download: Trichoblastoma