An unusual case of malignancy-related hypercalcemia

Abstract

Objective: To report the case of a 28-year-old woman who presented with hypercalcemia (total calcium =4.11 mmol/L), elevated parathyroid hormone (PTH) 24.6 pmol/L, normal parathyroid hormone-related peptide 7.8 pg/mL, and a 63 mm × 57 mm, poorly differentiated neuroendocrine carcinoma (small-cell type) pancreatic mass with liver metastases.

Investigations and treatment: Hypercalcemia was acutely managed with intravenous fluids, pamidronate and calcitonin. Investigations for multiple endocrine neoplasia type 1 and parathyroid adenoma were initiated. The identified neuroendocrine tumor was treated with cisplatinum/etoposide chemotherapy.

Results: The pancreatic mass (56 mm × 49 mm) and metastases decreased in size with chemotherapy and calcium levels normalized. Eight months later, calcium increased to 3.23 mmol/L, PTH increased to 48.2 pmol/L, and the pancreatic mass increased in size to 67 mm × 58 mm. The patient was given a trial of cinacalcet but was unable to tolerate it. Chemotherapy was restarted and resulted in a decrease in the pancreatic mass (49 mm × 42 mm), a reduction in PTH levels (16.6 pmol/L), and calcium levels (2.34 mmol/L).

Conclusion: Ectopic PTH secreting tumors should be considered when there is no parathyroid related cause for an elevated PTH. Recognizing the association between PTH and hypercalcemia of malignancy may lead to an earlier detection of an undiagnosed malignancy.

Keywords: hypercalcemia of malignancy; neuroendocrine tumor; parathyroid hormone; parathyroid hormone related-peptide.

Figure 1

PTH, PO4, and calcium levels for case study. Notes: Serum PTH, PO4, and Ca levels of a 28-year old, previously healthy patient with suspected ectopic production of PTH from a pancreatic neuroendocrine tumor on admission, following acute management of hypercalcemia and relative to the initiation of chemotherapy treatment. Abbreviations: PTH, parathyroid hormone; PO4, phosphate; Ca, calcium.

Figure 2

CT scan of case study patient. Notes: (A) CT-scan of the abdomen at diagnosis showing pancreatic mass (63.0 mm × 56.9 mm) and hepatic metastases at diagnosis. (B) A CT-scan of the abdomen after second course of chemotherapy showing a regression in the size of the pancreatic mass (47.9 mm × 42.1 mm). Abbreviation: CT, computed tomography.