Abstract
Mycosis fungoides (MF) is the most common variant of primary skin T-cell lymphoma. It typically manifests as an indolent progressing cutaneous eruption with erythematous scaly patches or plaques. Due to the nonspecific pathological findings, it can be easily misdiagnosed as psoriasis. A 34-year-old woman with a history of psoriasiform plaques for 12 years was referred to our dermatology clinic. In the beginning, the diagnosis of psoriasis was made and topical steroids were prescribed: it did not exhibit any clinical improvement. During the visit, skin biopsy was performed and the diagnosis of MF was confirmed. Treatment with PUVA, prednisolon, methotrexate, topical ointment including ucerin, urea, and clobetasol were initiated. Significant improvement in all lesions were observed after 1 month of the treatment, and within a year, the disease improved dramatically after PUVA therapy. In refractory cases of psoriasiform plaques that are progressive and/or ulcerative despite the optimal treatment, biopsy is required and a possible diagnosis of MF should be kept in mind.