Eruptive tumors of the follicular infundibulum presenting as hypopigmented macules on the buttocks of two Black African males

Abstract

We report two cases of eruptive tumors of the follicular infundibulum (TFI) with an unusual clinical presentation which has not been described previously in literature. In both cases, the appearance was strikingly similar, consisting of multiple asymptomatic hypopigmented macules on the buttocks of two Black African males, aged 38 and 55 years old. In both cases, the eruption had evolved over several months. The individual lesions were of similar size, approximately 1 cm, with irregular and ill-defined borders. Histopathological examination revealed a superficial and horizontal plate-like proliferation of keratinocytes emanating from the epidermis with multiple slender attachments. Pale keratinocytes were present within the epithelial plates. A Fontana stain showed a loss of melanin pigment from the epithelial plates. Orcein (elastic) stain highlighted an increase of the number of the elastic fibers surrounding the tumor. On the basis of these findings, a diagnosis of eruptive TFI was established for both cases. Among the various presentations of TFI, only the eruptive variant appears to be clinically distinctive, with asymptomatic hypopigmented macules usually located on the face, neck and upper trunk. Eruptive TFI should also be added to the clinical differential diagnosis of multiple hypopigmented macules on the buttocks of Black patients.