A Collision Tumor Comprising Early Gastric Adenocarcinoma and Diffuse Large B-cell Lymphoma after Endoscopic Gastric Submucosal Dissection

ABSTRACT

Concurrence of primary gastric adenocarcinoma and lymphoma have been described very rarely in the literature; its incidence is estimated at 0.08%. To our knowledge, there are no reports about a collision tumor comprising early gastric cancer and diffuse large B-cell lymphoma from the same lesion. The term "collision tumor" refers to the coexistence of two or more histologically distinct tumors within the same mass with no histologic admixture. A 76-year-old man complained of a 5-month-history of dyspepsia, and underwent esophagogastroduodenoscopy. Endoscopic findings showed a nodular, round, flat mass lesion in the upper body, therefore we performed endoscopic submucosal dissection (ESD). Pathologic findings revealed a well-differentiated adenocarcinoma accompanied by diffuse large B-cell lymphoma without evidence of Helicobacter pylori infection. Conventional CT and PET-CT scans revealed metastatic lymph nodes in the parotid gland, submandibular gland, maxillary gland and the inguinal regions. The pathogenesis of a collision tumor comprising two different cancers is not well understood. In addition, there are no established treatment guidelines in this series. In the current case, the patient underwent ESD for the removal of adenocarcinoma concomitantly with chemotherapy for the management of metastatic lymphoma.