Primary intestinal NK-cell lymphoma, EBV-negative: A case report and literature review

Primary intestinal NK-cell lymphoma (PINKL) is a rare entity with an overall poor prognosis. It is frequently EBV-positive and is characteristically negative for a T-cell gene rearrangement. Some parameters that may confer a relatively good prognosis include unifocality, the absence of intestinal perforation, and possibly EBV negativity. While exceedingly rare case reports of EBV-negative PINKL are available in the literature, the NK-cell phenotype of these lymphomas is determined solely by negative T-cell gene rearrangement studies. To the best of our knowledge, there has been no report of an EBV-negative PINKL that is defined by both flow cytometric evidence of absent surface CD3 expression as well as a negative T-cell gene rearrangement study. Furthermore, these reports do not include cytogenetic studies and/or next-generation sequencing (NGS) mutational analysis of the lymphoma. Thus, herein, we report a novel case of a stage I EBV-negative PINKL with an NK-cell phenotype confirmed by both flow cytometric immunophenotyping and a negative T-cell clonality study, describe its cytogenetic and next-generation sequencing (NGS) mutational profile, highlight the clinical course of the patient's 26-month follow-up, and review the relevant literature. The distinctive clinicopathologic findings of this case may expand our knowledge in understanding the biology of EBV-negative NK-cell lymphomas, which may differ from their EBV-positive counterparts.