Parathyroid carcinoma versus parathyroid adenoma in patients with profound hypercalcemia.

The metabolic manifestations and operative findings in 10 patients with a diagnosis of parathyroid carcinoma were analyzed to determine whether they differ from those in patients with parathyroid adenomas and similar degrees of hypercalcemia. Two groups of patients with parathyroid adenomas were used for comparison. Group A consisted of eight patients with "atypical" benign adenomas (mean preoperative level of serum calcium: 13.4 mg/dl); group B consisted of 13 patients with benign typical adenomas--all with preoperative serum calcium levels greater than or equal to 13.0 mg/dl (mean: 14.2 mg/dl). The patients with carcinoma (mean preoperative level of serum calcium: 15.3 mg/dl) had a frequency of osteoporosis and osteitis fibrosa cystica (50%) comparable with that of group A (33%) and group B (62%). Seventy percent of the patients with carcinoma had renal disease (nephrolithiasis, nephrocalcinosis, or impaired renal function), whereas only 38% of group A and 15% of group B had similar disorders. The patients with carcinomas had the highest frequency of combined bone and renal disease (50% versus 14% in group A and 15% in group B). Anemia, peptic ulcer disease, and hypertension occurred with similar frequencies in the three groups. Three patients with recurrent parathyroid carcinoma died of profound hypercalcemia, renal failure, or cardiac arrhythmia. In general, although patients with parathyroid carcinomas have more profound metabolic abnormalities than do patients with primary hyperparathyroidism, the metabolic manifestations in patients with parathyroid carcinoma are comparable with those in patients with parathyroid adenomas and profound hypercalcemia. Furthermore atypical adenomas share many anatomic and histopathologic features with parathyroid carcinomas, and distinguishing between the two is sometimes possible only in cases of tumor recurrence.