PARATHYROID CANCER - CLINICAL VARIATIONS AND RELATIONSHIP TO AUTOTRANSPLANTATION

Objective: To identify the clinical and pathological characteristics o f 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 terti ary-care referral centres in Ontario with specialty interest in diseas e of the thyroid and parathyroid glands. Patients: Sixteen patients, i dentified as has having parathyroid cancer (equivocal diagnosis in 9 a nd definitive diagnosis in 7). Main Outcome Measures: The clinical and histologic features, treatment, morbidity and mortality of parathyroi d cancer. Results: Some patients with an equivocal diagnosis had posto perative recurrent hyperparathyroidism characterized by multiple soft- tissue implants of parathyroid that persisted after reoperation. The o thers had infiltrative attachment of parathyroid lesions to the thyroi d gland and were eucalcemic and disease free up to 12 years after trea tment. Three of the seven patients with a definitive diagnosis of para thyroid cancer were treated for a neck mass; the others were treated f or hypercalcemia and multiple lytic bone lesions, hypercalcemia and re nal disease and secondary hyperparathyroidism. En-bloc resection, carr ied out in all but one case, was curative in five cases. The patient w ith secondary hyperparathyroidism underwent total parathyroidectomy an d 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 t reatment to avoid tumour spillage. Caution should be exercised in the use of donor parathyroid tissue for autotransplantation.