Genetic Predisposition and Multifocal Cancer: A Complex Case of Lynch Syndrome.

This case report describes the complex presentation and management of a 35-year-old man with synchronous malignancies: A well-differentiated grade 2 neuroendocrine tumor of the pancreas metastasized to the liver and bone, and invasive adenocarcinoma of the sigmoid colon. Strong clinical suspicion for Lynch syndrome arose due to the patient's family history and the loss of MSH1 and PMS2 protein expression in the colon adenocarcinoma. The patient presented with hypoglycemia, abdominal pain, and diarrhea. A multidisciplinary approach confirmed the diagnoses, including imaging studies (computed tomography, magnetic resonance imaging), biopsies, and immunohistochemistry; treatment involved endocrine management for hypoglycemia, planned surgical intervention (distal pancreatectomy, splenectomy, hepatic ablation), and consideration of systemic chemotherapy. Genetic testing for Lynch syndrome was initiated to guide long-term management and family screening. This case highlights the diagnostic and therapeutic challenges of managing multiple synchronous cancers, the importance of considering hereditary cancer syndromes, and the necessity of a coordinated multidisciplinary approach for optimal patient outcomes.