[Rare cause of hypercalcemia]. / Seltene Differenzialdiagnose einer schweren Hyperkalzämie.

ABSTRACT

We report a 47-year-old women who presented to her general practitioner and our hospital with weight loss of unknown etiology. Eight years previously she had undergone a hemithyroidectomy for nodular goiter with one cold nodule. Laboratory results revealed hypercalcemia, evidence of primary hyperparathyroidism and computer tomography of the thorax showed bilateral pulmonary metastasis. After undergoing CT-guided biopsy of a metastasis, histology revealed an endocrine primary tumor with low parathyroid hormone expression. In view of the history, clinical and biochemical findings we diagnosed a recently metastasized functioning parathyroid carcinoma, which eight years previously has been labeled as a benign atypical thyroid adenoma. The patient underwent surgical resection of all detected metastases. Afterwards the serum calcium and parathyroid hormone levels normalized. Parathyroid carcinoma is an uncommon tumor. In the absence of pathognomonic diagnostic criteria a definitive pathological diagnosis of parathyroid carcinoma often is not possible. The treatment of parathyroid carcinoma is essentially surgical. Patients with parathyroid carcinoma mostly die from uncontrollable hypercalcemia rather than from other tumor-related complications.