Turkish Journal of Pathology

Türk Patoloji Dergisi

Turkish Journal of Pathology

Turkish Journal of Pathology

2015, Vol 31, Num, 0     (Pages: 080-097)

Parathyroid Carcinoma: Diagnosis and Clinical Implications

Kai Duan 1,2, Özgür Mete 1,2,3

1 Department of Pathology, University Health Network, Toronto, Ontario, Canada
2 Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
3 Endocrine Oncology Site Group, Princess Margaret Cancer Centre, Toronto, Ontario, Canada

DOI: 10.5146/tjpath.2015.01316
Viewed: 6190
Downloaded : 3721

Parathyroid carcinoma is a rare type of endocrine cancer, with significant morbidity and mortality associated with parathyroid hormone (PTH)-mediated hypercalcemia. Concerning clinical features for parathyroid cancer include severe hypercalcemia (albumin-corrected calcium >3 mmol/L), a palpable neck mass (>3 cm), 3rd/2nd generation PTH assay ratio (>1), and intraoperative suspicion of local invasion or regional metastasis. A definite diagnosis of malignancy is rendered when a parathyroid tumor presents one of the following clinicopathological features: (1) vascular invasion, (2) perineural invasion, (3) gross invasion into adjacent anatomical structures, and/or (4) metastasis. In difficult cases, the use of ancillary biomarkers is critical to establish an accurate diagnosis. Recent advances in molecular pathology have uncovered the important role of CDC73/HRPT2, a tumor suppressor gene deregulated in parathyroid carcinomas. Loss of nuclear and/or nucleolar expression of parafibromin (the gene product of CDC73/HRPT2) is now regarded as a diagnostic, prognostic and predictive biomarker for parathyroid carcinoma. Furthermore, over 15-20% of seemingly sporadic parathyroid carcinomas have underlying germline CDC73/HRPT2 mutations. As a result, many centers have integrated the use of ancillary biomarkers, notably parafibromin staining, in their routine practise. Radical surgery with en bloc resection has emerged as a primary treatment modality in parathyroid cancer, achieving cure in some patients. However, in those with inoperable disease, there remains a dire need for new therapies, as current treatments are largely ineffective. This review provides an update on the current knowledge of parathyroid carcinoma and highlights its exciting changes in endocrine practice.

Keywords : Parathyroid neoplasms, Hyperparathyroidism, Atypical adenoma, HRPT2 protein, Parafibromin protein