Endocrine Abstracts

Primary hyperparathyroidism (PHPT) is usually caused by single adenoma. Functional parathyroid cysts are a rare cause of PHPT. Parathyroid cysts can be subdivided into nonfunctional, without biochemical derangement, or functional, with elevated serum calcium accompanying clinical evidence of hyperparathyroidism. Parathyroid cysts are found in the neck and anterior mediastinum. Functional parathyroid cysts are not only secretary but larger cysts can lead to compression symptoms, including dysphagia, dyspnoea, cough, stridor, and hoarseness. Mediastinum parathyroid cysts are usually presented as asymptomatic and identified accidentally by a routine chest X-ray or computed tomography (CT). We present a case of a patient with a functional parathyroid cyst.

Case: A 66-year-old male patients referred to our department because of hypercalcemia and anterior mediastinal mass determined on thorax CT done because of pulmoner embolism suspicion. He had no symptom of hypercalcemia except history of nephrolithiasis. Biochemical test revealed hypercalcemia with total serum calcium 12.24 mg/dl (8.8–10.2), phosphorus 2.98 mg/dl (2.5–4.5), parathyroid hormone (PTH) 140.6 pg/ml (15–65), creatinine 0.84 mg/dl (0.7–1.2), vitamin D 11.4 mg/l, and 24 h urinary calcium excretion was 504 mg/day. Renal ultrasonography determined 7 mm renal stone in the left kidney. Bone mineral dansitometry revealed osteopenia with −1.8 T-score. Thorax CT scan revealed a 4.7×3.3 cm sized solid mass, located in anterior mediastinum. After initiating of adequate hidration and furosemide treatment for hypercalcemia, the patient referred to chest and chest surgery department because of the anterior mediastinal mass and pulmonary embolism detected on thorax CT. The surgery decision was made because of the CT mass appearance. After removal of the mass calcium and parathyroid levels were reduced to normal levels. Pathologic examination revealed the diagnosis of a parathyroid cystic.

Mediastinal parathyroid cyst is an uncommon cause for hypercalcemia. It is difficult to establish a preoperative definitive diagnosis.