A case of lymphomatoid gastropathy: An indolent CD56-positive atypical gastric lymphoid proliferation, mimicking aggressive NK/T cell lymphomas.

Lymphomatoid gastropathy (LyGa) is a new evolving pathological entity that has been introduced recently. It is designated to describe CD56-positive atypical gastric lymphoid proliferation, mimicking NK/T cell lymphomas, that shows an indolent clinical course with spontaneous regression. We here present our experience with one new case diagnosed and treated in our hospital. An annual upper endoscopic check-up of a 50-year-old male with an unremarkable past history revealed a small reddish lesion on the posterior wall of the gastric angle. Endoscopic biopsy showed atypical cells of NK-cell lineage expressing CD56, CD16, CD3, perforin, and TIA-1, but not CD4, CD5, and CD8. Epstein-Barr virus encoded RNA was negative. The lesion regressed spontaneously after one month without treatment, but recurred two years later in a different site of the stomach with spontaneous regression again one month later. The recurrence of lymphomatoid gastropathy is very rare and should be diagnosed carefully to distinguish it from the aggressive lymphoma.