[A case of CD56+ extranodal NK/T-cell lymphoma, nasal type, presenting as a duodenal ulcer bleeding].

Extranodal NK/T-cell lymphoma is a recently recognized distinct entity within the World Health Organization classification of lymphoid tumors. It is relatively prevalent in Asian and South American populations. It most commonly occurs in the nasal or paranasal areas and less frequently in the skin, the soft tissue, and the gastrointestinal tract. Among these, extranodal NK/T-cell lymphoma of the gastrointestinal tract has shown an aggressive clinical course. We report a case of CD56+ extranodal NK/T-cell lymphoma presenting as a duodenal ulcer bleeding. A 62-year-old male patient presented with melena and abdominal pain. Endoscopic examination of the upper gastrointestinal tract showed the duodenal ulcer covered by blood clot. Pathologic examination revealed the diffuse infiltration of atypical lymphocytes with an angiocentric growth pattern, which was positive for CD3, CD56, and granzyme. The patient showed rapid deteriorating clinical course and died on day 14 after admission. Thus, we report this case with the review of literatures.