Peritoneal lymphomatosis confused with peritoneal carcinomatosis due to the previous history of gastric cancer: a case report.

Peritoneal lymphomatosis is a very rare disease of extranodal involvement of malignant lymphoma that is occasionally confounded with other peritoneal diseases. Herein, we reported the case of a 59-year-old woman who presented with massive ascites with prior history of stomach perforation during endoscopic procedure to treat early gastric cancer. Imaging studies showed massive ascites and tumor infiltration in the omentum and peritoneal wall. Initially, relapsed gastric cancer with peritoneal seeding was suspected based on the patient's history and imaging findings. However, final diagnosis was confirmed by ascites cytology as peritoneal lymphomatosis of diffuse large B-cell lymphoma unlike prior clinical information.