Extranodal natural killer/T‐cell lymphoma preceded by persistent hemifacial swelling

A 75-year-old man presented with a 6-month history of persistent swelling of the right cheek (Fig. 1a). He had neither subjective symptoms of the lesion nor systemic abnormalities, including B symptoms. A punch biopsy revealed only mild telangiectasia with perivascular lymphocytic infiltration. The swelling gradually decreased with prednisolone therapy, but discontinuation of the medication abrogated this favorable change. Another biopsy from the recurrent lesion revealed only perivascular and interstitial infiltration of lymphocytes and eosinophils. Seven months after the first visit, an asymptomatic ulcer appeared on the left shin (Fig. 1b), and an erythematous plaque appeared below the right nostril 1 month later (Fig. 1c). A biopsy from the ulcer revealed vasculitis and lymphocytic and histiocytic infiltration throughout the dermis. A biopsy from the plaque revealed lichenoid infiltration of lymphocytes. After one month, a new plaque appeared adjacent to the original facial plaque (Fig. 1d). A biopsy showed dense infiltration of numerous atypical lymphocytes (Fig. 2a), which stained positive for CD56, CD3, CD4, and Epstein–Barr virus encoded RNA in-situ hybridization but negative for CD8 and CD20 (Fig. 2b–f). No rearrangement of the T-cell receptor c gene was observed. Based on these findings, the patient was diagnosed with extranodal natural killer (NK)/T-cell lymphoma, nasal type. Immunohistochemical staining for CD56 and Epstein–Barr virus encoded RNA in-situ hybridization were also performed for the original biopsy specimens. The first two biopsies from the right