MON-908 Carcinoid Causing Catastrophic Calcemia

Intro: Carcinoid tumors are rare, slow growing, indolent neuroendocrine tumors typically originating from enterochromaffin in the gastrointestinal tract and bronchopulmonary tree(1). While often found to be secreting serotonin, many different secretory products have been described(2). We present the case of a patient with refractory hypercalcemia due to a carcinoid tumor producing parathyroid hormone related peptide (PTHrP). Case: A 65-year-old male was found to have hypercalcemia of 14.7 mg/dL after presenting for nausea and vomiting. He was treated with Zolendronic acid and intravenous (IV) fluids as initial work-up revealed an appropriately suppressed parathyroid hormone level, no monoclonal spike, and a PTHrP that was dramatically elevated. He refused further work-up initially but was admitted two months later for persistent severe hypercalcemia. Computed tomography imaging showed innumerable liver lesions. Histologic analysis of the largest liver lesion was consistent with carcinoid tumor. For the next two years, he was managed outpatient with Pamidronate, Denosumab, and Sandostatin, along with two liver embolizations. Control of serum calcium levels became more difficult and he had multiple hospitalizations for symptomatic hypercalcemia until chemotherapy, Sunitinib, was initiated. Calcium levels normalized for one year after starting Sunitinib prior to onset of suspected medication-induced pancreatitis. He was switched to Everolimus but did not respond to that and was readmitted mere weeks later for symptomatic hypercalcemia and a combination of Folinic acid, Fluorouracil, and Oxaliplatin (Folfox) was started. He continued to get frequent bisphosphonates and IV fluids along with Folfox but several months later he stopped responding to all medical options. His calcium level climbed to 19.9mg/dL and he underwent a technically complicated surgical procedure in which significant tumor burden was removed from his liver. Since surgery, the patient has remained normocalcemic without additional medical therapy. Discussion: Carcinoid tumors are uncommon with reported incidence of 40 per one million people(2). PTHrP is most commonly produced by squamous cell lung cancer, renal cell cancer, gynecologic cancers, and lymphoma(3). Carcinoid tumors producing PTHrP with resultant hypercalcemia is rare with a few cases reported in literature(4). Our patient had a complex treatment course including IV fluids, anti-resorptive agents, somatostatin analogs, liver embolization, chemotherapeutic agents, and eventual surgical debulking. Surgical intervention is not commonly required for carcinoid tumors(5). This patient had a rare tumor, producing an uncommon hormone, and required extensive treatment. This case shows the importance of a multidisciplinary approach in patients with hypercalcemia secondary to carcinoid tumors but refractory to traditional therapy.