Nodular Desmoplastic Trichoblastoma - Case Report and Review of Diagnostic Challenges

Trichoblastoma is a benign follicular neoplasm, exhibiting differentiation toward primitive hair germ structures. Desmoplastic variants are rare and may closely resemble invasive cutaneous carcinomas both clinically and histologically. The paper reports a nodular desmoplastic variant of trichoblastoma, arising on the scalp, in a 65-year-old woman. Four closely grouped nodules were initially present and completely excised. A fifth lesion developed at the same site 3.5 years later; no further recurrence occurred during another 5 years of follow-up. Histopathologic examination showed well-circumscribed dermal nodules, composed of cords and nests of basaloid cells, radiating from hyalinized stromal foci. Small foci of keratinization and mucinous change were observed. Deeper areas revealed spindle-shaped epithelial cells within a dense desmoplastic stroma, with focal infiltration of the epineurium and arrector pili muscle. The nodular desmoplastic variant of trichoblastoma represents a rare benign follicular neoplasm, that can mimic morpheaform basal cell carcinoma and other desmoplastic adnexal tumors. Recognition of this entity is essential to prevent overtreatment.