Hypercalcemia Due to Paraneoplastic Production of 1,25- Dihydroxyvitamin D in a Young Female with Dysgerminoma

Humoral hypercalcemia of malignancy (HHM) can be caused by ectopic paraneoplastic production of 1, 25 dihydroxy vitamin D due to the hyperactivity of the 1 alpha-hydroxylase enzyme. We present a case of a 19-year-old female who was admitted with bilateral dysgerminomas and significant hypercalcemia. Hypercalcemia was initially managed medically and then resolved with the surgical resection of the tumors. Although most cases are attributed to a high parathyroid hormone-related peptide (PTHrP) and bone metastases, <1% of cases can result from paraneoplastic production of 1,25 dihydroxyvitamin D due to increased activity of 1 alpha-hydroxylase.This is one of the rare cases of hypercalcemia, which not only adds to the limited number of cases of hypercalcemia associated with dysgerminoma but also is the first case report showing that vitamin D can be a paraneoplastic factor itself.