Parathyroid cancer: clinical variations and relationship to autotransplantation.

Objective: To identify the clinical and pathological characteristics of parathyroid cancer to determine the best method of treatment and to prevent the use of malignant tissue for autotransplantation.

Design: A chart review over a 20-year period (1973 to 1993).

Setting: Two tertiary-care referral centres in Ontario with specialty interest in disease of the thyroid and parathyroid glands.

Patients: Sixteen patients, identified as has having parathyroid cancer (equivocal diagnosis in 9 and definitive diagnosis in 7).

Main Outcome Measures: The clinical and histologic features, treatment, morbidity and mortality of parathyroid cancer.

Results: Some patients with an equivocal diagnosis had postoperative recurrent hyperparathyroidism characterized by multiple soft-tissue implants of parathyroid that persisted after reoperation. The others had infiltrative attachment of parathyroid lesions to the thyroid gland and were eucalcemic and disease free up to 12 years after treatment. Three of the seven patients with a definitive diagnosis of parathyroid cancer were treated for a neck mass; the others were treated for hypercalcemia and multiple lytic bone lesions, hypercalcemia and renal disease and secondary hyperparathyroidism. En-bloc resection, carried out in all but one case, was curative in five cases. The patient with secondary hyperparathyroidism underwent total parathyroidectomy and autotransplantation but died of metastatic parathyroid cancer 1 year later.

Conclusions: Because of the difficulty in making a histologic diagnosis of parathyroid cancer, en-bloc resection of the thyroid and parathyroid glands and locally invaded structures is the appropriate treatment to avoid tumour spillage. Caution should be exercised in the use of donor parathyroid tissue for autotransplantation.