Gastric T-cell lymphoma presenting with epithelioid granulomas mimicking tuberculosis in regional lymph nodes

In patients with malignant lymphomas, a sarcoid reaction is occasionally observed. However, lymphoma-related granulomas with caseous necrosis are rare. We describe such a case of T-cell gastric lymphoma that was difficult to diagnose. A 50-year-old man was referred to our hospital because of abnormal gastric endoscopic findings: hypertrophic folds with narrowing of the gastric lumen and multiple ulcers in the body. Gastric biopsy specimens showed non-specific inflammation. An open biopsy of the enlarged gastric regional lymph nodes was performed. The sections revealed effacement of the normal architecture and replacement by numerous epithelioid granulomas accompanied by Langhan's type giant cells with or without central caseous necrosis, strongly suggesting tuberculosis. However, mycobacteria and other causative organisms were not detected, and an anti-tuberculous regimen was ineffective. Repeat gastric biopsies were performed and, finally, atypical lymphocytes were observed infiltrating the mucosa. The patient was diagnosed with gastric T-cell lymphoma based on the results of immunohistochemical stainings. After chemotherapy, a total gastrectomy was performed. The diagnosis of gastric T-cell lymphoma with a sarcoid reaction was confirmed by histological findings of the sections. Namely, the gastric wall was replaced by atypical lymphocytes showing the phenotype of helper T cells, admixed with epithelioid granulomas with Langhan's type giant cells. Thus, this case suggests that regional lymph nodes in gastric lymphomas may be present as epithelioid granulomas with caseous necrosis, mimicking tuberculosis.