Correlation between clinical and histological findings in parathyroid tumors suspicious for carcinoma

Carcinoma of the parathyroid is a rare malignancy that can be cured surgically if the proper diagnosis and treatment is given initially. Arriving to the clinical suspicion of a malignancy preoperatively is by far the most important step for a good prognosis. Our goal is to review the correlation between clinical and final histopathological findings that can arouse the suspicion of such malignancy and their true predictive value in the diagnosis. All patients that underwent surgical removal of the parathyroid mass between March of 1992 and March of 2003 were reviewed retrospectively at Providence Hospital and Medical Centers. Among 168 patients who underwent parathyroid excision, 14 (8.3%) had hyperplasia of the parathyroid, 121 (72%) had benign adenoma, 25 (14.8%) had other benign lesions, and 8 (4.7%) patients had primary carcinoma of the parathyroid confirmed by pathology. Our mean serum calcium level was 11.57 mg/dL, which was lower than the mean level (12 mg/dL) for benign hyperparathyroidism. The mean tumor size was 2.18 cm, smaller than the proposed for malignant criteria, and none of the eight patients (0%) had any symptoms of hypercalcemia at the time of diagnosis. Seven of eight patients (87.5%) had frank signs of invasion together with other histological features, and two patients had associated papillary carcinoma of the thyroid. Five patients from our series did not meet clinical criteria for malignancy (tumor size > 3 cm, palpable mass, and serum calcium > 14 mg/dL), but had undisputable histological findings (high mitotic pattern, fibrous trabeculae, capsular invasion, vascular invasion, and nodular involvement). On the other hand, 17 patients with benign histology had tumors greater than 3 cm, and an additional 18 had palpable masses on physical examination. We believe that these patients need to be followed closely. The patients with diagnosis of parathyroid carcinoma, their kindred, and those with large adenomas may benefit from genetic screening for HRTP2 gene mutations in search of early detection of tumors suspicious for malignancy. This is based on the fact that we did not find correlation between the clinical presentation and the histological features in our patients with proven malignancy.