Adult T-cell leukemia/lymphoma with follicular mucinosis: an unusual histopathological finding and a commentary.

Overview

Follicular mucinosis is currently recognized as a histopathological finding characterized by the accumulation of mucin within follicular epithelium and is commonly associated with follicular mycosis fungoides (MF). We report the finding of follicular mucinosis in a cutaneous nodule of human T-lymphotropic virus type 1 (HTLV-1) associated adult T-cell leukemia/lymphoma (ATLL). The patient was a 69-year-old female of Caribbean descent with a history of ATLL who presented with erythematous nodules on the chest and abdomen. Histopathologic examination showed a pan-dermal infiltrate of medium-to-large sized atypical lymphocytes extending into follicular epithelium where they associated with large mucin deposits. Immunohistochemical stains showed that the atypical lymphocytes were positive for CD3, CD4 and CD25 and negative for CD30. Cutaneous lesions of ATLL, which often present histopathologically as an epidermotropic lymphoma with Pautrier-type collections, are often difficult to distinguish from MF. Until recently, lymphoma-associated follicular mucinosis seemed specific to MF and Sézary syndrome (SS), being reported only once in a lesion of ATLL. We report a second case of ATLL-associated follicular mucinosis to increase awareness of this possible association, and briefly review the literature of follicular mucinosis-associated hematologic malignancies, ultimately cautioning against the interpretation of all cutaneous lymphoma-related follicular mucinosis as MF/SS.