P025 Primary cutaneous extranodal natural killer/T-cell lymphoma, nasal type: a case report

Abstract Primary cutaneous extranodal natural killer/T-cell lymphoma, nasal type (ENKTCL) is a rare and aggressive subtype of cutaneous T-cell lymphoma (Kimura H, Fujiwara S. Overview of EBV-associated T/NK-cell lymphoproliferative diseases. Front Pediatr 2019; 6: 417; Jung JM, Yang HJ, Won CH et al. Clinicopathological and prognostic study of primary cutaneous extranodal natural killer/T-cell lymphoma, nasal type: a systematic review. J Dermatol 2021; 48: 1499–510). It frequently associates with Epstein–Barr virus (EBV) and manifests as ulcerative skin lesions, often mimicking infectious or inflammatory conditions. This report presents a 63-year-old man with chronic hepatitis B, presenting with painful indurated necrotic ulcers on the abdomen and left thigh. Initial misdiagnosis as ecthyma led to antibiotic therapy and debridement. Histopathological examination of the debrided tissue revealed EBV-positive lymphoid cells with angioinvasion, confirming ENKTCL. Immunohistochemical findings included aberrant CD20 expression, positive granzyme B and EBV-encoded RNA, and negative CD3 and CD56. Treatment with gemcitabine and oxaliplatin chemotherapy showed significant improvement, complemented by radiotherapy for refractory lesions. However, despite initial responses, the disease progressed, requiring ongoing combined chemoradiotherapy. ENKTCL primarily affects men aged 40–58 years and commonly involves the nasal cavity or extranasal sites like the skin and gastrointestinal tract. The disease often manifests as painless nodules that progress to necrotic ulcers with erythematous rims. Diagnosis relies on histopathology and immunohistochemistry, as ENKTCL often mimics other conditions. EBV is almost always present, detected via EBV-encoded RNA staining. In this case, aberrant CD20 expression posed a diagnostic challenge, resolved by negative PAX-5 immunostaining. ENKTCL management depends on disease staging, with early-stage lesions managed with radiotherapy and advanced cases requiring combined chemoradiotherapy. Concurrent chemoradiotherapy improves survival compared with monotherapy. This case underscores the importance of early recognition and accurate diagnosis of ENKTCL, given its aggressive course and poor prognosis. Histopathological evaluation and EBV testing are critical for differentiation from other conditions. While initial responses to chemoradiotherapy are promising, recurrence remains common, highlighting the need for vigilant follow-up and optimized therapeutic strategies.