Incidental synchronous intrathyroidal parathyroid carcinomas and papillary thyroid microcarcinoma with compressive neck mass and primary hyperparathyroidism: case report and literature review

Abstract

Background: Parathyroid carcinoma (PC) is a rare malignancy, often diagnosed incidentally through postoperative pathological examination. The occurrence of nodular goiter, intrathyroidal parathyroid carcinoma, contralateral parathyroid adenoma (PA), and papillary thyroid microcarcinoma (PTMC) is extremely uncommon, which prompted us to report our case experience.

Case presentation: We describe a 67-year-old male who presented with a cervical mass causing tracheal compression, which prompted him to seek medical advice. Based on preoperative auxiliary examination results from color Doppler ultrasound, SPECT parathyroid imaging, and blood tests, he was initially diagnosed with a suspected parathyroid adenoma and nodular goiter. Excision of the right lobe and isthmus of the thyroid, and left superior parathyroid gland was conducted, which were sent to intraoperative frozen pathological examination. During intraoperative observation, adhesion around the right thyroid lobe was discovered. Consequently, right central area lymph node dissection was performed due to suspicion of an aggressive malignant tumor. Histology and immunohistochemistry analysis revealed incidental intrathyroidal parathyroid carcinoma, contralateral parathyroid adenoma, classical papillary thyroid microcarcinoma, and nodular goiter.

Conclusion: Parathyroid carcinoma should be highly suspected when extremely high levels of PTH and severe hypercalcemia are present, which cannot be simply explained by a preoperatively localized parathyroid adenoma, especially when suspicious malignant adhesion is found during intraoperative exploration. In cases where multifocal thyroid nodules are associated with increased uptake of 99Tc-sestamibi, the possibility of coexisting carcinomas should be considered, not only for thyroid malignancy but also for the potential presence of intrathyroidal parathyroid carcinoma.

Keywords: Hyperparathyroidism; Intrathyroidal parathyroid; Papillary thyroid carcinoma; Parathyroid carcinoma.

Fig. 1

Thyroid contrast-enhanced ultrasound (CE-US) images. Multiple nodular goiter (A) and a parathyroid adenoma located in the middle and lower left thyroid lobe (B)

Fig. 2

Slight uptake signal at the posterior tubercle of the superior left thyroid lobe in 99Tc-sestamibi dual-phase SPECT (A) and parathyroid fusion imaging showed parathyroid adenoma in 15.5 mm*4.3 mm*4.8 mm (B)

Fig. 3

CE-CT demonstrated compression and displacement of the trachea and esophagus to the left by the nodule in the right thyroid lobe

Fig. 4

Histology and Immunohistochemical of intrathyroidal parathyroid carcinoma. (4a) The tumor is infiltrative within the thyroid. The expressions of chromogranin A (4b), PTH (4c), and Rb (4d) indicate that the cells originated in the parathyroid gland