Fine needle aspiration cytology of trichofolliculoma: a case report

The cytomorphology of skin adnexal tumours has not been described extensively in literature. We report the first case of trichofolliculoma, a hair follicle hamartoma, which was subsequently diagnosed by excision biopsy. A 19 year old woman presented with a nodule on the dorsal aspect of the finger which was clinically suspected to be a myxoid cyst. FNA showed several cohesive as well as arborising branched groups of squamous cells with evidence of keratinisation. The background had dispersed and loosely clustered sebaceous cells. The excision biopsy revealed a trichofolliculoma. Cytology is a useful tool in the diagnosis of skin adnexal tumours. The finding of cohesive, branching keratinized squamous cell clusters admixed with sebaceous cells may suggest a diagnosis of trichofolliculoma, as was seen in the present case.