The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2018

1,25-dihydroxyvitamin D-associated hypercalcemia in a metastatic pancreatic neuroendocrine tumour (#285)

Ayanthi A Wijewardene 1 , Koroush S Haghighi 1 , Sue Mei Lau 1
  1. Department of Endocrinology, Prince of Wales Hospital, Randwick, NSW, Australia

Hypercalcaemia is a common complication of malignancy, occurring in 20 to 30 percent of cases. Hypercalcaemia is occasionally seen in neuroendocrine tumours (NET) and is primarily attributed to secretion of parathyroid hormone-related peptide ( PTHrP) from tumours. We present a case of hypercalcaemia in a metastatic pancreatic NET which was associated with increased circulating 1,25-dihydroxyvitamin D.  Only one other case has been reported of hypercalcaemia with elevated 1,25-dihydroxyvitamin D in neuroendocrine tumour.

 A 53yo female presented with asymptomatic hypercalcaemia with a serum calcium of 3.35mmol/L. Parathyroid hormone (PTH) was appropriately suppressed at 0.6pmol/L. She had a mildly elevated PTHrP of 2.9 ( normal < 2pmol/L), 25-hydroxyvitamin D of 63mmol/L and inappropriately elevated 1,25-dihydroxyvitamin D of 389pmol/L ( 60-200). Computer tomography detected a  11x 5cm mass in the body and tail of pancreas with multiple hepatic metastases. Biopsy of her hepatic lesions was consistent with a neuroendocrine tumour, with positive staining of Cam5.2, chromogranin A and synaptophysin. Ki67 staining was 3%. Distal pancreatectomy and splenectomy were initially performed. The patient had persistent hypercalcaemia despite treatment with bisphosphonate therapy, denosumab and prednisolone. Hepatic embolization was followed by a two stage liver resection. Her treatment-resistant hypercalcaemia persisted with a calcium of 3.31mmol/L with a nearly five-fold elevation of circulating 1,25-dihydroxyvitamin D (924pmol/L) until all her hepatic metastases were resected. After her last resection, her calcium normalised to 2.40mmol/L and her 1,25-dihydroxyvitamin D  decreased to  162pmol/L. Lanreotide 120mg 4 weekly was commenced to achieve delay in tumour recurrence and 1,25-dihydroxyvitamin D levels have remained stable 6 months post operatively at 215pmol/L.