Lymphomatoidgastropathy mimicking extranodal NK/T cell lymphoma, nasal type: a case report.

Extranodal natural killer (NK)/T-cell lymphoma, nasal type, exhibits aggressive tumor behavior and carries a poor prognosis. Recently, lymphomatoid gastropathy with NK/T cell infiltration into gastric mucosa has been recognized as a pseudo-malignant disease which regresses without treatment. Because the conventional immunohistochemical criteria of lymphomatoid gastropathy is similar to that of extranodal NK/T-cell lymphoma nasal type, it is difficult to distinguish between the two conditions by histopathological evaluation only. Here, we report a rare case of lymphomatoid gastropathy in a 57-year-old female. Gastroendoscopy on routine check-up revealed elevated reddish lesions < 1 cm in diameter in the gastric fornix and body. Although repeat endoscopies at 1 and 6 mo later revealed no gastric lesions at any locations without any treatments, at 12 mo later gastric lymphomatoid lesions recurred at gastric fornix and body. Histological examination of endoscopic biopsy specimens at 12 mo showed atypical NK cell infiltration with CD3⁺, CD4⁻, CD5⁻, CD7⁺, CD8⁻, CD20⁻, CD30⁻, CD56⁺, CD79a⁻ and T-cell-restricted intracellular antigen-1⁺ into gastric mucosa. After treatment for Helicobacter pylori (H. pylori) eradication, the lesions disappeared in all locations of the gastric fornix and body over the subsequent 12 mo. Here, we report a case of H. pylori-positive lymphomatoid gastropathy with massive NK-cell proliferation, and also review the literature concerning newly identified lymphomatoid gastropathy based on comparison of extra nodal NK/T-cell lymphoma nasal type. In any case, these lesions are evaluated with biopsy specimens, the possibility of this benign entity should be considered, and excessive treatment should be carefully avoided. Close follow-up for this case of lymphomatoid gastropathy is necessary to exclude any underlying malignancy.