Identification of Pancreatic Neuroendocrine Tumor During Evaluation for Severe Valvulopathy in a Patient With a History of Lung Carcinoid Tumor: A Case Report.

A 36-year-old man with a history of resected typical lung carcinoid tumor and bicuspid aortic valve presented with acute decompensated heart failure. Workup revealed severe mitral valvulopathy and incidentally identified an enhancing pancreatic head mass with additional lesions on imaging. Liver biopsy was benign, while endoscopic ultrasound-guided biopsy of the pancreatic mass showed a well-differentiated, WHO grade 1 pancreatic neuroendocrine tumor (NET) positive for chromogranin, synaptophysin, and CD56, with Ki-67 < 3%. Serum 5-hydroxyindoleacetic acid (5-HIAA) and chromogranin A were elevated. Positron emission tomography (PET)-DOTATATE demonstrated somatostatin receptor-avid lesions in the pancreas, liver, bone, and lymph nodes, consistent with metastatic neuroendocrine neoplasm. The patient underwent aortic valve replacement followed by long-acting octreotide therapy. Concurrent duodenal biopsies revealed celiac disease, and his gastrointestinal symptoms improved with a gluten-free diet. This case represents an exceptionally rare scenario of pancreatic neuroendocrine tumor in a patient with prior lung carcinoid tumor and raises the critical question of pancreatic metastasis versus a second primary NET in the absence of hereditary syndromes. It underscores the need for heightened vigilance for second primary malignancies (SPMs) and atypical metastatic patterns in patients with a history of NETs and highlights the importance of multidisciplinary evaluation for accurate classification and optimal management.