Recurrent renal secondary hyperparathyroidism caused by supernumerary mediastinal parathyroid gland and parathyromatosis: A case report

Abstract

Background: Surgical parathyroidectomy (PTX) is necessary for patients with severe and progressive secondary hyperparathyroidism (SHPT) refractory to medical treatment. Recurrence of SHPT after PTX is a serious clinical problem. Both supernumerary mediastinal parathyroid gland and parathyromatosis are the rare causes of recurrent renal SHPT. We report a rare case of recurrent renal SHPT due to supernumerary mediastinal parathyroid gland and parathyromatosis.

Case presentation: A 53-year-old man underwent total parathyroidectomy with autotransplantation due to the drug-refractory SHPT 17 years ago. In the last 11 months, the patient experienced symptoms including bone pain and skin itch, and the serum intact parathyroid hormone (iPTH) level elevated to 1,587 pg/ml. Ultrasound detected two hypoechoic lesions located at the dorsal area of right lobe of the thyroid gland, and both lesions presented as characteristics of hyperparathyroidism in contrast-enhanced ultrasound. ^99mTc-MIBI/SPECT detected a nodule in the mediastinum. A reoperation involved a cervicotomy for excising parathyromatosis lesions and the surrounding tissue and a thoracoscopic surgery for resecting a mediastinal parathyroid gland. According to a histological examination, two lesions behind the right thyroid lobe and one lesion in the central region had been defined as parathyromatosis. A nodule in the mediastinum was consistent with hyperplastic parathyroid. The patient remained well for 10 months with alleviated symptoms and stabilized iPTH levels in the range of 123-201 pg/ml.

Conclusion: Although rare, recurrent SHPT may be caused by a coexistence of both supernumerary parathyroid glands and parathyromatosis, which should receive more attention. The combination of imaging modalities is important for reoperative locations of parathyroid lesions. To successfully treat parathyromatosis, all the lesions and the surrounding tissue must be excised. Thoracoscopic surgery is a reliable and safe approach for the resection of ectopic mediastinal parathyroid glands.

Keywords: case reports; hyperparathyroidism; parathyromatosis; recurrence; secondary; supernumerary parathyroid glands.

Figure 1

Preoperative imaging modalities were used to find and locate the parathyroid tissues. (A) US revealed two hypoechoic lesions with volumes of 0.55 cm × 0.45 cm and 0.55 cm × 0.35 cm (arrow) located at the dorsal area of right lobe of thyroid gland. (B) In CEUS, both lesions appeared as characteristics of parathyroid tissues (fast in the early phase, slow out in the late phase, and higher enhancement with a long enhancement time). (C) ^99mTc-MIBI planar early (15 min) and delayed (3 h) static images showed that there is no tissue with focal tracer accumulation presented at the primary surgery site of neck. (D) ^99mTc-MIBI planar early (15 min) and delayed (3 h) static images showed that there is no focal tracer accumulation at the autograft site. (E) The axial CT (E1 and E2) and SPECT/CT (E3 and E4) images showed soft-tissue masses with marked MIBI uptake in the left upper mediastinum (arrows). US, ultrasound; CEUS, contrast-enhanced ultrasound; ^99mTc-MIBI, ^99mTc-sestamibi.

Figure 2

Excision of suspected recurrent parathyroid tissues and pathologic analysis. (A) Two suspected parathyroid lesions (A1–2, arrow) located at the dorsal area of right lobe of thyroid gland were resected. One suspected parathyroid lesion (A3, arrow) located on the central region of right neck was found during exploration, and then clearance of the central neck compartment was performed. A thoracoscopic surgery also was performed to remove a mediastinal parathyroid gland (A4, arrow). (B) Histopathology (hematoxylin–eosin staining  ×200) showed that the lesions at the site of primary surgery (B1–3) were consistent with the pathological features of parathyromatosis. The resected mediastinal parathyroid gland had demonstrated nodular hyperplasia of parathyroid tissue, which was well differentiated (B4). (C) An extensive surgery that involved the excision of suspected parathyroid lesions and the clearance of the central neck compartment was performed, and the postoperative picture had been shown. (D) A thoracoscopic surgery to remove mediastinal parathyroid gland had been performed, and the postoperative picture had been shown.

Figure 3

^99mTc-MIBI/SPECT was used to demonstrate whether the suspected parathyroid tissues had been missed. (A) ^99mTc-MIBI planar early (15 min) and delayed (3 h) static images showed that there is no tissue with focal tracer accumulation that presented in the primary surgery site of neck. (B) A weak focal tracer accumulation had presented in the autograft site. (C) The axial CT (C1 and C22) and SPECT/CT (C3 and C4) images showed no tissue with MIBI uptake in the mediastinum. ^99mTc-MIBI, ^99mTc-sestamibi; CT, computed tomography.