General Medical Information

Parathyroid Cancer

Parathyroid carcinomas are rare tumors that usually present in the fourth decade. Most parathyroid carcinomas are sporadic, but familial isolated hyperparathyroidism is a rare autosomal dominant disorder associated with an increased risk of cancer.[1] Approximately 1% to 2% of cases of hyperparathyroidism are caused by parathyroid cancers. Functioning cancers produce parathyroid hormone (parathormone) which causes symptoms of hypercalcemia or evidence of bone or renal disease. These symptoms usually lead to early detection. Because benign adenomas and carcinomas of the parathyroid gland may appear histologically similar, a diagnosis of cancer is often confirmed only through a retrospective examination of the malignant clinical course (local invasion, metastases or recurrence).[2] Parathyroid carcinoma should be suspected clinically if (a) hypercalcemia is severe (>14 milligrams per deciliter), (b) a cervical mass is palpated in a hypercalcemic patient, or (c) hypercalcemia is associated with unilateral vocal cord paralysis. Patients rarely die from the tumor itself, but from cardiac or renal complications, or from the metabolic effects of hyperparathyroidism.[3] The tumor’s slow growth makes surgery an option for localized disease and for selected patients with metastases. Not all tumors are functioning.

Signs and symptoms found in decreasing incidence at diagnosis include: subcortical bone resorption, palpable neck mass, renal calculi, renal disease, peptic ulcer, pancreatitis, muscle weakness, and vomiting. Serum parathormone or effluent from the thyroid veins via selective catheterization and retrograde venography are presurgical confirmatory diagnostic tests. Postresection symptoms of hypercalcemia suggest recurrence. The most common sites for distant metastases are lung, bone, and liver.

References

1. Wassif WS, Moniz CF, Friedman E, et al.: Familial isolated hyperparathyroidism: a distinct genetic entity with an increased risk of parathyroid cancer. J Clin Endocrinol Metab 77 (6): 1485-9, 1993.

2. Vetto JT, Brennan MF, Woodruf J, et al.: Parathyroid carcinoma: diagnosis and clinical history. Surgery 114 (5): 882-92, 1993.

3. Palnaes Hansen C, Lau Pedersen M, Christensen L: Diagnosis, treatment and outcome of parathyroid cancer. A report of eight patients. Eur J Surg 157 (9): 517-20, 1991.