Abstract
RATIONALE: Recently, the incidence of polyoncosis has been increasing due to advancements in treatment, such as antitumor therapy, which led to a prolonged survival. However, few patients with metastatic pancreatic ductal adenocarcinoma (PDAC) develop second tumors, which render a poor prognosis. We report a rare case of PDAC, which is metachronous with a fatal malignant lymphoma (ML). PATIENT CONCERNS: A 68-year-old woman who had been monitored due to liver cirrhosis secondary to hepatitis C virus infection presented with a 10-mm pancreatic head cancer with lung metastasis and had started an anticancer therapy with gemcitabine. Approximately 18 months after diagnosis, lymphadenopathies around the pancreas were noted, which eventually spread to the entire body over time. DIAGNOSIS: Diffuse large B-cell lymphoma was diagnosed using biopsies from cervical lymph nodes. INTERVENTIONS AND OUTCOMES: The patient started a gemcitabine + rituximab regimen; however, the patient died from cachexia-associated lymphoma progression, not PDAC. LESSONS: ML should be considered when intra-abdominal lymphadenopathies are detected in patients with pancreatic cancer, and ML should be differentiated from lymph node metastasis of pancreatic cancer.