Endocrine Abstracts

Introduction: Parathyromatosis is a rare cause of recurrent hyperparathyroidism defined as small nodules of hyperfunctioning parathyroid tissue in the soft tissues of the neck or mediastinum. The most common cause is probably the implantation of parathyroid cells into surrounding tissue during surgery and the risk of parathyromatosis increases with repeated parathyroid surgery. There is an overlap in the histologic features in parathyromatosis, atypical adenoma, and parathyroid carcinoma. Parathyromatosis still remains a difficult diagnostic a therapeutic task. We describe two cases of parathyromatosis in reccurent primary hyperparathyroidism. Both cases were negative in genetic testing for mutations in MEN1, RET, CASR and 14 other genes associated with hereditary parathyroid diseases.

Case Report 1: 64 years old woman was referred to the third parathyroid surgery for recurrent hyperparathyroidism. Laboratory: calcium 2,8 mmol/l, PTH 12,92 pmol/l (normal range 1,3 - 7,6), normal renal function. Previous surgery: 1. parathyroidectomy of one left parathyroid gland in 2012, 2. bilateral neck exploration with removal of the left cervical thymic tissue (containing parathyroid adenoma) and the fragment tissue (supposed parathyroid adenoma) from the right side in 5/2021. The fragment tissue from the right side consisted of adipose tissue with two foci of parathyroid tissue. The third surgery represented unilateral right cervical exploration with block cervical subcutaneous tissue removal and removal of the lower right thyroid pole in 10/2022. Histopathology: nodular parathyroid tissue with smooth noninfiltrative borders, without capsules, no vascular invasion, without mitotic activity – corresponding to parathyromatosis.

Case Report 2: 52 years old women was referred to the fourth parathyroid surgery for recurrent hyperparathyroidism. Laboratory: calcium 2,79 mmol/l, PTH 24,6 pmol/l (normal range 1,3 - 7,6), normal renal function. Previous surgery: 1. total thyroidectomy + left upper parathyroid removal in 2008, 2. focused left parathyroid removal in 2019, 3. parathyroidectomy of 2 adenomas (both right) and pretracheal thymic tissue removal with parathyroid adenoma and other fragment of parathyroid tissue in 1/2021. The fourth surgery represented unilateral right exploration with removal of one lower right adenoma and pretracheal adipose tissue resection in 2/2022. Histopathology: noduli of parathyroid tissue corresponding to hyperplasia or parathyromatosis.

Conclusion : Our two cases represent parathyromatosis after repeated surgery. Both of them were referred for reoperation with only mild hypercalcemia. Excesive repeated parathyroid surgery should be carefully considered. Supported by Ministry of Health Czech Republic - DRO (Institute of Endocrinology - EÚ, 00023761)