Rhypercalcemia: Rare Finding of Renal Cell Carcinoma Metastasis to Parathyroid Adenoma

Presentation Number: SAT 324
Date of Presentation: April 1st, 2017

Sridevi Challa1, Richa Sharma2, Ali Ghazanfari3, Kanaan Abow Alkhier4 and Mohamad Hosam Horani*5
1Banner Baaywood hospital, 2American University of Integrative Sciences School of Medicine, 3Banner Baywood Hospital, 4Arizona Oncology, 5Alsham Endocrinology, Chandler, AZ

Abstract

Renal cell carcinoma (RCC) is the third most common neoplasm to metastasize to the head and neckregion, where 85% of the reported cases do not constitute of head and neck findings. Parathyroid

involvement is a rare occurrence and hypercalcemia may occur in certain patients with advanced cases of

RCC.

 We present a case of a 50 year old female who complained of menorrhagia following hysterectomy

due to uterine fibroids and a past medical history of anxiety. Consequently, there was an incidental finding

of hypertension and hypercalcemia with an initial serum calcium level of 11.6 mg/dl and albumin of

3.7g/dl. The physical exam findings were negative. Patient reported a previously elevated calcium level

above 11 mg/dl two years ago, that was left untreated. She denied use of calcium or vitamin D

supplements.

Further lab evaluation displayed elevated PTH of 192 pg/ml, decreased 25-OH vitamin D of

below 4ng/ml, decreased TSH of 0.37 mu/ml, and normal Free T4 1.23 ng/dl. Tc-99m Sestamibi

parathyroid scan showed parathyroid adenoma in the region of left lower parathyroid gland. Computed

tomography of abdomen/pelvis revealed a large left adrenal mass measuring 3.7 cm x 2.5 cm.

Subsequently, the patient had left parathyroidectomy performed, where the histopathology displayed

hypercellular parathyroid tissue consistent with parathyroid adenoma, along with an incidental finding of

high nuclear grade malignant nodule with features of clear cell carcinoma, suggestive of primary renal

origin. The nuclear stain results were positive for GATA3 and negative for TTF-1 and GCDFP, where

GATA3 links the tumor to RCC variants. Post-parathyroidectomy, calcium normalized to 8.8 mg/dl.

Discussion : Metastatic spread to the parathyroid gland from other cancers may occur in approximately 10% of

reported cases. This spread may be explained by the rich blood supply present specifically in endocrine

tumors. Following the finding of parathyroid adenoma, further workup revealed no renal mass on imaging,

instead, a left-sided adrenal mass was found. The adrenal mass biopsy displayed benign findings. Some

probable theories, for the absence of a renal neoplasm, may include the presence of an autoimmune

phenomenon behind RCC or even spontaneous regression of RCC after metastasis. However

 spontaneous regression of RCC is a rare (1%), but known phenomenon, with several theoretical

models described in the past. Our patient shows us the value of following up on incidental lab findings,

with a specific focus on rare causes of such irregularities.

Conclusion: Although unusual, metastasis to the parathyroidgland from RCC is a possibility, thus patients with presenting features of hypercalcemia should be

evaluated further for primary hyperparathyroidism. Appropriate workup and management of

hypercalcemia can potentially lead to early detection of underlying neoplasms and improvement of

survival as well as patient quality of life

 

Nothing to Disclose: SC, RS, AG, KA, MHH