Parathyroid carcinoma; facts and views

Introduction Behind of the thyroid gland, there are four glands named parathyroid which help the regulation of the calcium levels across the human body (1). Parathyroid carcinoma (PC) is the most rare cause of primary hyperparathyroidism which is one of the most common endocrine disease. It typically affects the elderly women and men and its clinical appearance is characterized by mild hypercalcemia, traditional classic bone, kidney manifestations and elevation of parathyroid hormone and often resulting in severe hypercalcemia (1,2). PC has also been reported rarely in patients with secondary hyperparathyroidism (2,3). The signs and symptoms of PC are renal stones, bone pains, osteoporosis, abdominal pain and weight loss. Physical examination may also reveal a cervical mass on population. The biochemical abnormalities are elevated serum calcium levels with concomitantly elevated parathyroid hormones levels (24). It has also been described in several patients with endstage renal disease too (5). However, there is no agreed staging system for PC, thus there is not possible to provide patients with a solid prognosis (6). This disease occurs in patients of all ages, and there is no prediction for either sex. Histopathological criteria are key outcome predictors in PC (6). Physical examination may reveal a cervical mass on population. Epidemiology Primary hyperparathyroidism is an important endocrine disease in general population (7). In fact, majority of the patients with primary hyperparathyroidism may show somehow benign or malignant tumors (6-8). The overall incidence of primary hyperparathyroidism is reported to be one in every 1000 persons and PC could account for 1% of all cases of primary hyperparathyroidism (4). In addition, familial primary hyperparathyroidism could also increase the risk of PC (9). On the other hand, the morbidity and mortality of PC is associated with the complications of hypercalcemia which is managed with surgical removing after proper identification (10), that is why PC should be taken into account in the differential diagnosis of hypercalcemia by clinicians (11). Moreover, PC is one of the rarest known cancer, even much rare among children under 16 years old (12), which might be occurred sporadically and could account for about 0.72.1% (13), 0.5%-5% (14) [on average 1% (15)] of patients with early primary hyperparathyroidism. Furthermore, although PC is rare, but it is an important cause of death in the group of patients with primary hyperparathyroidism and it accounts for 0.7%-2.1% of all cases of primary hyperparathyroidism, with an incidence of 0.4 to 0.6 per million based on surveillance, epidemiology and end result data (6). Abstract Because of the rare nature of parathyroid carcinoma, few physicians and surgeons have had experience in management of this disease. Although parathyroid carcinoma is not a common cancer, however, in patients with early hyperparathyroidism is very important, especially due to its mortality. Parathyroid carcinoma could occur equally between two genders but the incidence of parathyroid carcinoma is increasing worldwide despite its rare occurrence, with youth and being female as two important related factors. There is no available lifestyle factor related to parathyroid carcinoma. In fact, the cause of parathyroid carcinoma is yet to be established and there is no data to confirm causal relationships between parathyroid carcinoma and any risk factor, although it may be some relations with familial and sporadic forms.