Endocrine Abstracts

Introduction

The ectopic parathyroid adenoma (EPTA) is the most common cause of failed parathyroid surgery. Most often localisations are intra-thymic and intra-mediastinal adenomas. We report a rare presentation of a symptomatic parathyroid adenoma located in ectopic retropharyngeal position diagnosed after surgical treatment of primary hyperparathyroidism (PHPT).

Obsevation

A 42-year-old female was referred to internal medecine department with fortuitous discovery of hypercalcemia. She had no medical history and there was no family history of multiple endocrine neoplasia syndrome or parathyroid disorder. On physical examination, her blood pressure was 100/65 mmHg. There was no palpable neck mass. Electrocardiogram was normal. Laboratory investigations revealed an elevated serum calcium level at 3.04 mmol/l [2.2- 2.6 mmol/l], hypophoshatemia of 0.52 mmol/l [0.81–1.62 mmol/l]. Serum parathyroid hormone level was markedly increased 287.7 pg/ml [15–65 pg/ml]. Urinary calcium rate was elevated.Her thyroid function test was normal. Diagnosis of hypercalcemic crisis resulting from PHPTwas retained and surgical treatment was indicated. Preoperative Neck US showed left mediolober thyroid nodule TIRADS4 and parathyroid scintigraphy showed lower cervical fixation and left upper plolarhypofixation corresponding to parathyroid adenoma. The patient underwent a lower right paratyroidectomy with an upper left loboisthmectomy. Histological examination showed left lobe adenoma and right lower parathyroid hyperplasia. The postoperative course was favorable. Three months later, she presented recurrent hypercalcemia, hypophosphatemia and increased PTH level at three times normal rate. Neck US and scintigraphy were negative for PTA or thyroïd disease. Cervical CT showed an ectopic retropharyngealparathyroid adenoma which previously had been dismissed as a nonpathological lymph node. The patient was referred again for revesion surgery.

Discussion

PHPT is commonly the result of parathyroid adenoma, less frequent the result of hyperplasia or multiple adenomas. Excision of adenoma is currently curative for primary PHPT but surgery failure and recurrent hypercalcemia are usually due to ectopic adenoma. Retropharygeal space is rarely reported as an area for EPTA.It is thought to be due to the common embryologic origin of the superior parathyroid gland and the apex of the piriform sinus from the fourth branchial pouch.The goal of preoperative imaging in PHPT is not only to identify solitary PTA or multigland disease but also to detect ectopic adenoma.

Conclusion

This case highlights the retropharyngeal space as an important and rare ectopic site for parathyroid adenoma that must be researched carefully before surgery to avoid surgical revision. We insist on using multiple imaging technics to increase the chance for detection of ectopic adenomas.