Parathyroid Carcinoma: Etiology, Diagnosis, and Treatment

Abstract

The goal of the present study was to make our medical practice evidence-based for patients with parathyroid carcinoma. We posed six clinical questions relevant to the management of parathyroid cancer. A comprehensive search and critical appraisal of the literature was then carried out. Most of the literature retrieved was retrospective in design and differed in the definition of carcinoma. The distinction between unequivocal and equivocal carcinoma (or atypical adenoma) was not always made for the study populations. None of the studies indicated reproducibility of outcome measures. Of the histopathological features described in the literature based on the description of Schantz and Castleman, capsular/vascular invasions and trabecular growth pattern were the most specific, and fibrous bands were the most sensitive. None of the patients with "atypical adenoma" developed recurrence, whereas 25% of those with "equivocal carcinoma" did. Mutations in HRPT2, the gene responsible for hereditary hyperparathyroidism with jaw-tumor syndrome, were strongly associated with sporadic parathyroid carcinoma. Severe hypercalcemia and its related clinical symptoms, extremely high levels of parathyroid hormone, osteitis fibrosa cystica, a palpable neck mass, and a relatively large depth-width ratio on ultrasonography, are the important features of parathyroid carcinoma. Disease-specific survival rates reported in the literature were varied, reflecting the differences in the definitions of carcinoma, study populations, and interventions. To establish valid evidence for patient management in the future, a collaboration of endocrine specialists is essential to conduct well-designed clinical studies for this rare disease.