title: [Unusual localization in primary hyperparathyroidism].
abstract: BACKGROUND
  Cystic degenerations of parathyroid adenoma appear in 4 to 5% of all cases. These tumors might be localized in the mediastinum. Until now very few cases of cystic parathyroid adenoma have been published. Difficulties in the diagnosis are common because these adenomas are often thought to belong to other anatomic structures. Persistence of hyperparathyroidism and elevated surgical complications can be the consequences.
  
  
  METHODS
  We report on the case of a 76-year-old patient with primary hyperparathyroidism. Pre-operative ultrasound revealed a suspicious lesion near the left upper lobe of the thyroid and an unclear cystic structure in the upper posterior mediastinum, suspected as cervical cyst or dysontogenetic cyst. Additional investigations concerning the cystic mediastinal lesion suggested 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 parathyroid adenoma. Postoperatively calcium, phosphate and PTH levels returned to normal.
  
  
  CONCLUSIONS
  In patients with primary hyperparathyroidism, unclear cystic mediastinal masses should be taken into consideration.
authors.affiliation: Medizinische Klinik mit Schwerpunkt Gastroenterologie, Hepatologie und Endokrinologie, Universitätsklinikums Charité, Humboldt-Universität zu Berlin.
authors.forename: S
authors.initials: S
authors.lastname: Rickes
authors.forename: B
authors.initials: B
authors.lastname: Schmidt
authors.forename: H
authors.initials: H
authors.lastname: Gerl
authors.forename: H
authors.initials: H
authors.lastname: Lochs
mesh_terms: D000368:Aged; D003537:Cystadenoma / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D003937:Diagnosis, Differential; D006801:Humans; D006961:Hyperparathyroidism / Q000209:etiology*; D008297:Male; D008479:Mediastinal Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D010282:Parathyroid Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000601:surgery