Parathyroid tumors

[Parathyroid carcinoma]

BACKGROUND

Parathyroid carcinoma is the least frequent malignancy among endocrine tumors. In the most reported series of patients with primary hyperparathyroidism the incidence of carcinoma is less than 1%. Racognition by a surgeon that the parathyroid tumor is malignant, and the performance of an adequate en bloc removal of primary lesion, with histologic diagnosis offer the best treatment of a patient with this unusual malignancy.

CASE REPORT

We reported a 30-year-old patient with parathyroid carcinoma, primary hyperparathyroidism, and recurrent nephrocalcinosis. Marked hypercalcemia, low serum phosphorus, and substantial elevation of serum parathyroid hormone indicated a diagnosis of primary hiperparathyroidism. General symptoms were anorexia, muscle weakness, back pain and depression. Ultrasonography done before the surgery revealed a 2 cm upper left parathyroid gland with solid and cystic areas. The neck exploration was done with en block resection of the tumor. A histopathological evaluation confirmed the diagnosis of parathyroid carcinoma. Over more than a three-year-follow-up, the patient had no evidence of the disease recurrence and his serum PTH and calcium levels remained within the normal.

CONCLUSION

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism. Preoperative diagnosis remains a challenge. Radical en bloc resection of the tumor is the treatment of choice for this malignancy.

Proliferation of parathyroid cells negatively correlates with expression of parathyroid hormone-related protein in secondary parathyroid hyperplasia

BACKGROUND

Parathyroid hormone-related protein (PTHrP) is now suspected to act as an autocrine or paracrine regulator of cell growth or differentiation, although it was originally reported as a hypercalcemic substance in malignancies. This study was performed to assess the relationship between PTHrP expression and cell proliferation in human parathyroid glands.

METHODS

The localization of PTH and PTHrP was studied in 42 samples of hyperplastic parathyroid from 14 long-term hemodialysis cases with immunohistochemistry and in situ hybridization. Results were compared with proliferative activity (proliferating cell nuclear antigen index: counts of proliferating cell nuclear antigen-positive cells/100 cells). The localization of the PTH/PTHrP receptor was also examined. Ten normal glands were studied as controls.

RESULTS

In hyperplasia, cells positive for PTH, PTHrP, or both were observed immunohistochemically. The areas expressing PTHrP mRNA completely coincided with those positive for PTHrP immunohistochemically. Oxyphilic or transitional oxyphilic cells were consistently positive for PTHrP. PTH/PTHrP receptors were located in the cytoplasmic membrane in most parathyroid cells. Proliferating cell nuclear antigen-positive cells were rare in normal glands with an index of 0. 22 +/- 0.09 (mean +/- sem). They were significantly increased in hyperplastic cases but less for PTHrP-positive than for -negative cells (1.25 +/- 0.16 as compared with 7.80 +/- 0.52; P < 0.0001).

CONCLUSION

The observed low level of proliferation of PTHrP-positive cells suggests a functional role for PTHrP as a possible growth suppressor in the human parathyroid.

Clinical course of metastatic parathyroid cancer

In a retrospective study the clinical course of 40 patients with symptomatic persistent or recurrent parathyroid cancer was analyzed in order to assess the value of aggressive surgical intervention. Recurrence was diagnosed after a median period of 33 months (1-228 months). Twenty-two patients had locoregional disease, whereas 14 patients had both local and distant spread. The remaining four patients had distant spread. Patients with just locoregional disease were subject to one to nine reoperative procedures. The median survival time from the last operation was 39 months (1-204 months). Eight patients then had no evidence of disease, three were hypercalcemic and 9 of 11 had died of parathyroid cancer. Distant spread was demonstrated in 17 of 40 patients. Pulmonary metastases predominated (14 of 17). Surgical excision was performed in 9 of 14 cases. Of these nine, two patients had a subsequent disease-free interval of 36+ and 72+ months, respectively. One patient was reported hypercalcemic after 84 months, whereas five patients died of cancer between 4 and 60 months after their last surgical exploration. One patient was lost to follow-up. In all, 21 patients (53%) died of parathyroid cancer. Conspicuous nuclear atypia and frequent mitoses predominated. Image cytometric DNA analysis showed high rates for all three groups (median p90 = 80%, range 21-98%).