Gastrointestinal Neuroendocrine Tumor, Colon Adenocarcinoma, and Hyperparathyroidism: An Unorthodox Synchronism

Synchrony of colorectal adenocarcinoma with neuroendocrine tumor (NET) and hyperparathyroidism with colon adenocarcinoma is a rare entity, reported in a handful of cases. We authors would like to report a rare case of coexistence of poorly differentiated colon adenocarcinoma, NET of appendix and hyperparathyroidism. A 43-year-old Caucasian female was diagnosed with metastatic colon adenocarcinoma involving the caecum and appendiceal orifice. The resected specimen also confirmed presence of concurrent well-differentiated NET in distal half of appendix. For this patient, serum chemistry was significant for severe hypercalcemia with elevated parathyroid hormone and fairly normal range parathyroid hormone-related peptide. Importantly, association among the aforementioned conditions remains elusive and warrants further research; nevertheless, surveillance procedures could be performed in patients, if a correlation exists at all.