Synchronous Primary Diffuse Large B Cell Lymphoma and Adenocarcinoma of the Stomach: a Clinical Dilemma

A 65-year-old Caucasian man was admitted to our department with progressive weakness, dyspepsia, and weight loss. Endoscopic biopsies revealed a gastric diffuse large B cell lymphoma. Computed tomography scan showed a locally advanced bulky gastric tumor with peritoneal involvement. Laparoscopic staging was performed and biopsies showed peritoneal localization of adenocarcinoma. A new endoscopy with multiple mapping biopsies confirmed the diagnosis of diffuse large B cell lymphoma. A multidisciplinary team evaluated the stage of both tumors and the patient started on a chemotherapy regimen with cisplatin, 5-fluorouracil, and trastuzumab (ToGA). He is currently alive with disease at 9 months after surgery. Synchronous occurrence of primary lymphoma and adenocarcinoma of the stomach is extremely rare. Symptomatology is similar and accurate diagnosis requires a combination of both morphological and immunohistochemical analyses. Treatment should be planned considering the stage of both diseases.