BACKGROUND

Tumor of the follicular infundibulum (TFI) is a relatively rare tumor which clinically presents as a solitary keratotic papule usually on the head and neck which on microscopic examination typically reveals a plate-like fenestrated epithelial tumor composed of pale staining cells.

METHODS

We describe a new variant of TFI. An 80-year-old male with a history of multiple basal cell carcinomas and a squamous cell carcinoma presented with a 2-year history of a red, scaly, slightly elevated plaque on the lateral aspect of his right buttock.

RESULTS

Histopathological examination revealed plate-like reticulate epithelial outgrowths of large and pale cells with foci of sebaceous differentiation and numerous colloid bodies. Differential diagnosis included superficial basal cell carcinoma with sebaceous and ductal differentiation, tumor of the follicular infundibulum, an unusual fibroepithelioma of Pinkus or an eccrine fibroadenoma with sebaceous differentiation.

CONCLUSIONS

This case illustrates a hybrid adnexal tumor with histologic features common to both tumor of the follicular infundibulum and superficial epithelioma with sebaceous differentiation.