Endocrine Abstracts

Introduction

Parathyroid carcinoma is a rare endocrine carcinoma, which represents less than 1% of all cases of primary hyperparathyroidism. It usually affects people between 44–55 years old without differences between sexes. Sometimes it is related to HRPT2 gene mutations and it has a variable prognosis.

Presentation of case

A 56-year-old man was referred to our centre to complete an hypercalcemia study. He had an unremarkable past medical history and he did not take any regular medications. He presented a few months history of asthenia and weight loss. Serum investigations: Calcium 12.8 mg/dl (Albumin corrected), P: 2.14 mg/dl, PTH 578 pg/ml, 25-OH vitamin D: 33 nmol/l, Glomerular filtration rate: 53.45 ml/min. On examination he had a firm, well defined right thyroid nodule. Neck ultrasound revealed a 46.2 mm (TI-RADS 5) nodule in right thyroid lobe and a 18.6 mm (TI-RADS 4) nodule on left thyroid lobe. On the first nodule the fine needle aspiration citology (FNAC) showed a probably parathyroid carcinoma meanwhile on the second nodule FNAC showed an atypia of undetermined significance (Bethesda III). 99 mTc thyroid scintigraphy demonstrated an hypermetabolic mass on right lower parathyroid gland. CT scan showed an heterogeneous hypodense mass with lobulated margins, and inner calcifications, which displaced the trachea and contacted the lower pole of the right thyroid lobe and esophagus. Until surgery treatment with cinacalcet at progressive doses was started achieving lower calcium values (10.9 mg/dl). Intraoperatory biopsy informed about nodule with marked nuclear atypia cell proliferation and solid growth pattern; undergoing total thyroidectomy and lower right radical parathyroidectomy. Pathologist confirmed parathyroid carcinoma with marked nuclear atypia, inflammatory component and signs of focal vascular invasion. The other nodule was described as hyperplasic. After surgery PTH was 49.5 pg/ml and calcium levels were 9.4 mg/dl 24 hours later. In the follow up the patient presented hypocalcemia and needed high calcium doses and vitamin D supplies. This prolonged requirement despite of calcium supplies in addition to a bone densitometry which informed of osteoporosis leaded us to a postsurgical hungry bone syndrome. At present the patient keeps stable and pending of genetic study result.

Conclusion

– Parathyroid carcinoma should be considerated in the differential diagnosis of hypercalcemia. – An early diagnosis and surgical resection is essential to reduce morbidity and mortality. – Genetic study can help to detect this pathology in relatives.