Parathyroid Cancer, a Continued Diagnostic and Therapeutic Dilemma: Report of Four Cases and Review of the Literature

Parathyroid cancer presents a diagnostic challenge as a rare endocrine malignancy usually not recognized preoperatively and often not conclusively identified intraoperatively. We examined a cluster of parathyroid cancers treated at University of Louisville-affiliated hospitals during a 5-year interval. Clinical and histologic data from patient records at University Surgical Associates, the University of Louisville Hospital, Norton Hospital, and the Louisville Veterans Administration Medical Center in Louisville, KY were retrospectively reviewed. During the study interval surgical exploration of the neck was undertaken on 175 patients with primary hyperparathyroidism; four parathyroid malignancies (2%) were identified. Three of the four patients exhibited symptomatic hyperparathyroidism with very high diagnostic calcium and parathormone levels. All patients had multiple coexisting diseases and two had undergone previous parathyroid surgery. Sestamibi scan localized the lesion in two patients, ultrasound was used in one patient, and a positron emission tomography scan was needed to identify the lesion in the fourth. Intraoperative findings varied from multiple nodules involving the thyroid and paratracheal nodules to otherwise normal-appearing enlarged parathyroid gland. External pathologic review was needed to conclusively establish the diagnosis in all cases, even though initial histologic analysis was suggestive of malignancy. All patients are alive, well, and free of disease. This rarely occurring malignancy may be suggested by very high preoperative calcium parathormone levels. Intraoperative and histologic findings are often inconclusive resulting in therapeutic decisions made by the operating surgeon on the basis of limited or incomplete information.