Ectopic Production of Intact Parathyroid Hormone By Poorly Differentiated Neuroendocrine Carcinoma

Presentation Number: SAT 328
Date of Presentation: April 1st, 2017

Heba Albasha1, Waseem Albasha2, Basel Imam3, Kanaan Abow Alkhier4 and Mohamad Hosam Horani*5
1Midwestern AZCOM, CHANDLER, 2University of Arizona college of Medicine, 3Saint Joseph Hospital, 4Arizona Oncology, 5Alsham Endocrinology, Chandler, AZ

Abstract

Humoral hypercalcemia of malignancy is a well-described paraneoplastic syndrome most often associated with breast, renal, and squamous cell lung cancers. It is typically caused by ectopic production of parathyroid hormone-related protein (PTHrP). A handful of case reports, however, have described patients with humoral hypercalcemia of malignancy without elevated PTHrP, but rather with elevated intact parathyroid hormone (PTH) levels. This case report describes a patient with a history of endometrial cancer status post resection via total abdominal hysterectomy and bilateral salpingo-oophorectomy and radiation therapy who presented with abdominal pain. Computed tomorgraphy (CT) of the abdomen revealed a new left adnexal mass, with repeat CT imaging revealing lung and liver lesions consistent with possible metastases. She was found to have hypercalcemia and elevated intact PTH, but undetectable PTHrP. Labs showed no kidney disease or vitamin D deficien cy. Neck exploration was done, with excision of two parathyroid glands; pathology showed normal parathyroid tissue. Biopsies were taken of the adnexal mass and liver lesions. Pathology suggested the adnexal mass was a poorly differentiated neuroendocrine carcinoma of probable gastrointestinal origin, mixed with recurrent endometrial carcinoma. The liver lesions were metastases consistent with the same neuroendocrine carcinoma found in the adnexal mass, with the report noting the appendix as a possible origin given the CDX-2 staining pattern of the mass. This case would represent one of only a few reports in the literature of a gastrointestinal neuroendocrine carcinoma associated with hypercalcemia of malignancy that demonstrated increased intact PTH as the cause of hypercalcemia rather than PTHrP. This case is also unique in that it describes such a neoplasm mixed with a separate carcinoma. Literature review did not reveal a similar case for comparison. This case provides an importa nt lesson to the medical literature: intact PTH is perhaps a more common cause of hypercalcemia of malignancy than once thought. Patients presenting with a new mass and with that appears to be new onset primary hyperparathyroidism may in fact have this atypical cause of humoral hypercalcemia of malignancy

 

Nothing to Disclose: HA, WA, BI, KA, MHH