Lymphocytic Gastritis Identified by Abnormal PET Scan

A 20-year-old man presented for evaluation of diffuse abdominal pain. He had completed chemotherapy 2 months earlier for stage IV diffuse large B-cell lymphoma (DLBCL). On a recent positron emission topography (PET) scan, he was found to have a new area of intense activity within the proximal stomach (Figure 1). Upper endoscopy showed scattered shallow ulcers throughout the stomach (Figure 2). Gastric biopsies demonstrated lymphocytic gastritis-type pattern with acute inflammation and reactive gastropathy (Figure 3). On further immunostaining, the lymphocytes were CD3+ T-cells rather than the B-cells expected in recurrent DLBCL. This confirmed the diagnosis of lymphocytic gastritis. Helicobacter pylori and celiac disease serologies were negative. His symptoms resolved within a few days of daily proton pump inhibitor (PPI) usage, and upper endoscopy and repeat PET demonstrated resolution (Figure 4)