Endocrine Abstracts

Background

Cystic parathyroid adenoma is a rare entity (<0.01% of all cervical masses) that leads to primary hyperparathyroidism in 9% of cases. Parathyroid scintigraphy is essential for the diagnosis although there are pitfalls with false negative results. Parathyroidectomy is the treatment of choice but its success depends on the exact preoperative localization of the parathyroid lesions. 4D-CT is a very helpful diagnostic tool in such cases.

Case presentation

A 43-year-old man presented with a history of recurrent episodes of nephrolithiasis. Cervical ultrasound was indicative of multiple isoechoic thyroid nodules and 3 cystic hypoechoic lesions behind the middle and lower part of both thyroid lobes. The biochemical examinations indicated primary hyperparathyroidism. Thyroid function tests, calcitonin and urine metanephrines were in normal range. ΜIBI scintigraphy showed one parathyroid adenoma behind the lower part of the left thyroid lobe. Since there was no accordance between the two diagnostic procedures, cervical MRI followed, demonstrating 7 small lesions, indicative of parathyroid adenomas or lymph nodes. A 4D-CT Scan revealed 3 mixed solid and cystic lesions ranging from 2 to 2.8 cm, posteriorly to both thyroid lobes. The patient underwent total thyroidectomy because of multinodular goiter and parathyroidectomy according to the 4D-CT. The histological examination demonstrated the coexistence of 1 right and 2 left mixed cystic parathyroid adenomas and a unifocal right lobe papillary thyroid carcinoma invading the thyroid parenchyma. There was a significant decrease in PTH levels after the excision of the adenomas.

Conclusions

Simultaneous mixed solid and cystic multiple parathyroid adenomas and papillary thyroid carcinoma is an extremely rare entity. Functional imaging has low sensitivity in displaying cystic lesions. It is worth noting that 4D-CT is a very important preoperative diagnostic tool in cases of discrepant functional (Sestamibi) and structural (ultrasonography) imaging.

References

1) Simultaneous intrathyroidal parathyroid adenomas and multifocal papillary thyroid carcinoma in a patient with kidney transplantation: a case report

Jun Yang, BMC Nephrol 2019 Nov 9;20(1):405

2) Cystic parathyroid adenoma: Primary hyperparathyroidism without ^99m Tc-MIBI uptake , Rev Esp Med Nucl Imagen Mol Jul-Aug 2017;36(4):254–256