A case of recurrent pseudolymphomatous folliculitis: A mimic of cutaneous lymphoma

Pseudolymphomatous folliculitis is a rare entity. We present a 62-year-old man with a recurrent solitary nodule on his nose requiring multiple excisions. Microscopic examination of the excisions showed a dense lymphocytic infiltrate containing numerous histiocytes and S100⁺, CD1a⁺ dendritic cells that surrounded and infiltrated hypertrophic hair follicles. Diffuse sheets of CD3⁺ T cells and nodular clusters of CD20⁺ B cells were also seen. There was normal reactive pattern of follicular centers. Light chain restriction was not detected. T-cell receptor and immunoglobulin heavy chain gene rearrangements by polymerase chain reaction revealed negative findings. A diagnosis of pseudolymphomatous folliculitis was made based on the hypertrophic hair follicles, periadnexal S100⁺ and CD1a⁺ dendritic cells, and negative clonal gene rearrangement study findings. This case of recurrent pseudolymphomatous folliculitis is instructive because of the resemblance to cutaneous lymphomas and cutaneous lymphoid hyperplasias, and the need for correct diagnosis to avoid overtreatment of this indolent condition.