Primary cutaneous γδ‐T‐cell lymphoma treated with low‐dose methotrexate and narrowband ultraviolet B irradiation: Report of a case with testicular involvement

Primary cutaneous γδ-T-cell lymphoma (CGD-TCL) is a rare entity of cutaneous T-cell lymphomas (CTCL) and is characterized by tumoral growth of mature γδ-T-cell expressing cytotoxic molecules. The prognosis of CGD-TCL is generally worse than other CTCL. However, relatively indolent patch/plaque lesions have been described suggesting the heterogeneous nature of this entity. Here, we present a case of CGD-TCL with various skin manifestations, such as erythematous plaques/tumors and subcutaneous panniculitis-like lesions. During the follow up, testicular involvement was detected, which was surgically removed. Histopathology showed mixed features from epidermotropism, dermal infiltration and subcutaneous panniculitis-like lesions depending on the clinical manifestations. The tumor cells were positive for CD3 and revealed cytotoxic markers, TIA-1 and perforin, but not for CD4, CD8, CD20, CD56, TCRβF1 or EBER. Topical glucocorticoid ointment, narrowband ultraviolet B (NB-UVB) irradiation and low-dose methotrexate (MTX) were effective to control these skin lesions. No visceral involvement was detected thereafter. While CGD-TCL is usually associated with poor prognosis, it seems to be composed of various clinical manifestations, and NB-UVB and low-dose MTX could be a choice for indolent patch/plaque and possibly nodular lesions, especially for the aged.