Unusual localization in primary hyperparathyroidism

Background: Cystic degenerations of parathyroid adenoma appear in 4 to 5% o f all cases. These tumors might be localized in the mediastinum. Until now very feu cases of cystic parathyroid adenoma have been published. Difficult ies in the diagnosis are common because these adenomas are often thought to belong to other anatomic structures. Persistence of hyperparathyroidism an d elevated surgical complications can be the consequences. Case Report: We report on the case of a 76-year-old patient with primary hy perparathyroidism. Pre-operative ultrasound revealed a suspicious lesion ne ar the left upper lobe of the thyroid and an unclear cystic structure in th e upper posterior mediastinum, suspected as cervical cyst or dysontogenetic cyst. Additional investigations concerning the cystic mediastinal lesion s uggested the following differential diagnoses: goiter (X-ray), bronchogenic cyst, cervical cyst or esophageal diverticulum (CT). During the operation no adenoma could be found on the left side, but when the cystic mediastinal lesion was finally removed it turned out to be a giant cystic activated pa rathyroid adenoma. Postoperatively calcium, phosphate and PTH levels return ed to normal. Conclusion: In patients with primary hyperparathyroidism, unclear cystic me diastinal masses should be taken into consideration.