Bilateral synchronous parathyroid carcinoma in a patient on long-term hemodialysis: presentation of a rare clinical case and review literature.

Synchronous bilateral carcinoma of the parathyroid in subjects undergoing prolonged hemodialysis is an extremely rare pathology. After observing a clinical case, we reviewed the literature on parathyroid carcinoma. We describe the clinical case of a 61-year-old man with synchronous bilateral carcinoma of the parathyroid. He had a long history of terminal renal insufficiency and had been undergoing hemodialysis for about 18 years before being referred to us with a diagnosis of secondary hyperparathyroidism. The patient underwent total parathyroidectomy and total thyroidectomy. The interoperative parathormone assay displayed a 68% decrease in parathyroid hormone (PTH) compared with baseline value, and the histologic examination of the two inferior parathyroid glands revealed the presence of invasive parathyroid carcinoma. After reviewing the case, we hypothesized that in the presence of chronic parathyroid stimulation, the hyperplasia of the gland may subsequently be transformed into carcinoma. In patients undergoing hemodialysis, the predominance of females in cases of carcinoma of the parathyroid might be accounted for by a hormonal mechanism or by statistical artifacts attributable to the small number of case histories available. Further analysis was made of the apparently favorable prognosis of this type of patient compared with sporadic parathyroid carcinomas; the mean follow-up period reported in the literature was 42.2 months, with a relapse rate of 15.8%.