Primary Hyperparathyroidism Caused by Ectopic Parathyroid Adenoma: Experience Sharing and Literature Review

Abstract

In parathyroid surgery, the incidence of ectopic parathy-roid glands was 6.3% to 16%. In parathyroid gland reop-eration, the incidence of ectopic parathyroid glands was 45%. The inferior parathyroid gland is most common ectopic located in the former mediastinum, often embedded in the thymus. The superior parathyroid gland is often located in the posteri-or longitudinal mediastinum. According to the reports, Prima-ry Hyperparathyroidism (PHPT) caused by mediastinal para-thayroid adenoma has a more severe clinical manifestation and higher serum calcium more likely to have bone involvement. Therefore, early diagnosis of mediastinal ectopic parathyroid adenoma is essential. When PTH and calcium ions was eleva-ted and diagnosis of primary hyperparathyroidism was clear, if 99mTc-MIBI scintigraphy was negative, ectopic parathyroid glands might need to be considered. We need choose other auxiliary examination methods such as neck-chest CT or MRI, and expand the scope of the 99mTc-MIBI scan, including the neck and mediastinum. Understand the predilection sites of ectopic parathyroid glands, frequency, and its scoping, helps to locate ectopic parathyroid before and during surgery. The uptake of 99mTc-MIBI has been associated with factors such as blood flow, size, and mitochondrial activity in parathyroid hyperplasia/adenomas. When parathyroid adenoma cystic deg-eneration occurs, located in the thyroid, small in size, asym-metrically hyperplastic or when the function is not significant, 99mTc-MIBI is easy to show false negatives. The results of false positives in the mediastinum may be metastatic lung cancer, thymomas, seminomas, or lymphomas. Raising awareness of ectopic parathyroids to reduce clinical missed, misdiagnosed and easily to find ectopic parathyroid glands is of great help. Our hospital had treated a case of PHPT caused by ectopic parathayroid adenoma in the mediastinal, now reported as follows.