An 80-year-old woman was found to have a 40-mm depressed-type gastric cancer. Computed tomography showed multiple lymph node enlargement, including paraaortic lymph nodes. The extent of lymph node enlargement was significant compared with the depth of the primary lesion. We conducted distal gastrectomy, D2 lymph node dissection, and a paraaortic lymph node biopsy. Microscopically, the tumor was diagnosed as mucosal cancer. In the dissected lymph nodes, noncaseating granuloma was found without metastasis of adenocarcinoma. Immunohistochemical staining using Propionibacterium acnes-specific antibodies showed a large number of P. acnes-positive cells in the granulomas. Finally, the tumor was diagnosed as early-stage gastric cancer and sarcoidosis.
Keywords: PAB antibody; Propionibacterium acnes; gastric cancer; sarcoid reaction; sarcoidosis.