Poikilodermatous Mycosis Fungoides: A Rare Case Treated with Low-Dose Methotrexate

Mycosis fungoides (MF) is a subtype of cutaneous T-cell lymphoma (CTCL) and a primary cutaneous lymphoma. Poikilodermatous MF (PMF) is a rare clinical variant of MF. Systemic chemotherapy, such as methotrexate (MTX), may be administered as monotherapy or in combination at low doses in MF. A 64-year-old man with PMF has been reported. History and physical examination revealed hyperpigmented and hypopigmented macules on the chest, abdomen, both arms, back, and upper legs, along with erythematous macules on the right medial thigh. The diagnosis of PMF is based on clinical manifestations and histopathological features of atypical lymphocyte cell infiltration in the epidermis. In addition, immunohistochemical examination also supports the MF diagnosis. The patient received chemotherapy consisting of monotherapy with MTX at low doses. During the third month of observation following MTX therapy, a few of the hyperpigmented and hypopigmented macules appeared to have diminished; some of the erythematous macules had transformed into hyperpigmented macules, and there were no new lesions. The purpose of therapy is to control the disease. Administration of low-dose MTX as a monotherapy may result in clinical improvement, but further observation is necessary. PMF may have a better prognosis than other clinical variants of MF.