Clinical presentation: Occurs in men after the fifth decade of life and presents as a small solitary nodule on the face.

It is frequently misdiagnosed clinically as a basal cell carcinoma or a papilloma.

Microscopic features: 

Characterized by extensive sclerotic stromal component together with complex strands of clear epithelial cell in the periphery ;

Desmoplastic changes are present in the deep and central portion of the lesion ;

Stroma is also present in the centre of epithelial nodules ;

Eosinophilic, amorphous alcian blue and PAS-diastase positive material is present (basement membrane material) ;

CD34 positive cells are identified ; Stroma contains vimentin positive cells.

Differential diagnosis:

Inverted seborrheic keratosis ;

Spindle cell squamous cell carcinoma and desmoplastic basal cell carcinoma (spindle cell component in desmoplastic trichilemmoma merge with surrounding stroma, resembling infiltrating carcinoma).

Related post: Pathology of Trichilemmoma

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Desmoplastic trichilemmoma.

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