Benign Indolent CD56-Positive NK-Cell Lymphoproliferative Lesion Involving Gastrointestinal Tract in an Adolescent.

The gastrointestinal (GI) tract is the most common site of primary extranodal lymphomas. Although B-cell non-Hodgkin lymphomas account for the majority of GI lymphoma, T- or natural killer (NK)-cell lymphomas, including peripheral T-cell lymphoma, enteropathy-associated T-cell lymphoma (EATL), extranodal NK/T-cell lymphoma, and anaplastic large cell lymphoma, also involves the GI tract.1,2 T- or NK-cell lymphomas are an aggressive disease typically managed with systemic chemotherapy or radiotherapy; however, pathologic diagnosis of intestinal T- or NK-cell lymphoma based on a small biopsy specimen is often challenging. Recently, a unique clinicopathologic entity involving GI tract and characterized by an atypical proliferation of NK-cells has been described under the term "NK-cell enteropathy" or "lymphomatoid gastropathy."3,4 All afflicted patients were adults and had no history of celiac disease. Endoscopic findings were variable with superficial ulceration, edema, hemorrhage, and the presence of small, elevated lesions from stomach to colon. Histologically, the lamina propria of the mucosa was infiltrated by atypical NK-cells. Tests for Epstein-Barr virus (EBV) were negative, and T-cell monoclonality was not detected. Although these lesions can pathologically mimic intestinal NK- or T-cell lymphoma to the extent that some patients were diagnosed with lymphoma, all patients had a benign clinical course. Thus, early recognition of this entity could be important for appropriate disease management. Here we report the first Korean case, as well as the first case in an adolescent, of NK-cell enteropathy.