A 33?year?old woman presented with painful erythematous nodules on both pretibial areas that had developed 3 months ago[Figure 1]. She had no prodromal symptoms and had history of neither oral nor genital ulcers. On the first visit, blood and urine examination and chest x?ray findings were normal. She had no relevant past medical history. Initial biopsy of a skin lesion revealed septal panniculitis with mixed inflammatory cells that had infiltrated the junctions of the septa and mild perivascular infiltration [Figure 2]. Based on these clinical and histological data, we diagnosed erythema nodosum and prescribed oral methylprednisolone, colchicine and talniflumate. Despite taking these medications for 2 months(including an increase in the methylprednisolone dose), the lesions advanced to the trunk and showed aggravation with the development of ulceration on the previous leg lesions [Figure 3]. The erythrocyte sedimentation rate was increased (54 mm/h), but all the other blood and urine tests were normal. Repeat biopsy of the lower leg lesion revealed prominent nodular infiltrations of atypical lymphocytes throughout the dermis and subcutaneous layer as well as angiocentric destruction caused by dense atypical infiltrates in the subcutis. The cells were positive for CD3, CD8, CD56 and Epstein?Barr virus by in?situ hybridization [Figure 4]. A bone marrow biopsy revealed no evidence of malignant lymphoma, but a few atypical lymphocytes were observed in the peripheral blood smear. A computed tomographic scan of chest and pelvis showed some enlarged lymph nodes, without hepatosplenomegaly. The diagnosis of the patient was revised ? to extranodal NK/T?cell lymphoma. The skin lesions exhibited remission, followed by resolution after 6 cycles of dexamethasone, methotrexate, ifosfamide, L?asparaginase, and etoposide. However, the cancer relapsed after 6 months and the patient is currently on the waitlist for allogenic haematopoietic stem cell transplantation.
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