Parathyroid Carcinoma: a Review

Abstract

Parathyroid cancer is a rare endocrine malignancy with only a few thousand cases reported worldwide. As a result, there exists considerable controversy regarding the various aspects of this disease, viz., etiology, diagnosis, and management. We hereby attempt to review the literature on parathyroid carcinoma (PC) and summarize the practices based on the current evidence available. The majority of the PC are sporadic although an association with hyperparathyroidism-jaw tumor syndrome, multiple endocrine neoplasia (MEN) 1 and 2, and isolated familial hyperparathyroidism has been shown. As preoperative diagnosis is challenging, PC should be suspected in patients presenting with a neck mass with signs and symptoms of invasion to surrounding structures. Skeletal and renal symptoms are often associated with PC as presenting complaints. The biochemical parameters are more pronounced in the case of PC compared with benign countpart. Due to its rarity, the American Joint Committee of cancer control (AJCC) acknowledges that as yet a clear distinct staging system to prognosticate the disease would be premature. Complete excision with negative margins at first surgery offers the best chance of cure. The role of radiotherapy (RT) is still unclear; however few series have suggested a better locoregional control with adjuvant RT. Recurrences are common and are most significantly associated with an incomplete clearance at initial surgery. Surgical salvage of recurrent/metastatic disease with medical management of hypercalcemia is the treatment of choice. Large prospective studies and trials need to be conducted to understand the pathology better and improve management protocols; however this is a challenge due to rarity of cases.

Keywords: Endocrine cancers; Hypercalcemia; Parathyroid neoplasms; Parathyroid neoplasms/ diagnosis; Parathyroid neoplasms/ surgery.

Fig. 1

High frequency ultrasound of the neck shows a well-defined hypoechogenic mass (white arrow) arising at the inferior pole of thyroid gland compressing adjacent thyroid parenchyma (Circle).The mass extends into the tracheo-esophageal groove.(Trachea marked with star)

Fig. 2

Right inferior parathyroid Carcinoma in a 33-year-old male patient. a Axial Contrast Enhanced CT (CECT)image of the neck shows a relatively well defined heterogeneously enhancing lesion(white arrow) abutting the right lobe of thyroid extending into the right tracheoesophageal groove(Star). b Sagittal Reformatted CECT image shows parathyroid lesion (white arrow) with lytic lesion involving vertebral body of 10th Dorsal vertebra (yellow arrow) with collapse and associated soft tissue component, suggestive of Brown’s Tumor

Fig. 3

Histomorphological and immunohistochemical features of parathyroid carcinoma. a Low power view highlights the nodular architecture of parathyroid carcinoma with broad bands of fibrosis separating the nodules of tumor cells. H and E, ×40. b Infiltration of skeletal muscle by parathyroid carcinoma. H and E, ×100. This is one of the diagnostic features of Parathyroid carcinoma; other being Lymphovascular space invasion [(D), Hand E, ×40). c Macronucleoli and tumor cell necrosis (shown by an arrow). H and E, ×200. Immunohistochemistry findings shows that the tumor is diffusely and strongly positive for Chromogranin [(E), DAB, ×100)] and is negative for Thyroid transcription factor 1[(F), DAB, ×100)]