title: Resection of a large ectopic parathyroid adenoma: A case report.
abstract: BACKGROUND
  Parathyroid adenomas are the most common cause of primary hyperparathyroidism. However, cases of parathyroid adenomas greater than 4cm with osteitis fibrosa cystica are extremely rare. Herein, we report a case of resection of a large ectopic mediastinal parathyroid adenoma.
  
  
  METHODS
  A 46-year-old female with chief complaints of bone pain and gait disturbance was referred to our hospital. Physical examination revealed many mobile teeth in her oral cavity, distortion of the vertebral body, and bowlegs. Laboratory tests showed hypercalcemia, hypophosphatemia, and elevated serum levels of intact parathyroid hormone. Chest CT revealed a 42-mm well-defined, enhancing mass in front of the left-sided tracheal bifurcation. Her findings were diagnosed as primary hyperparathyroidism due to an ectopic mediastinal parathyroid tumor. We performed a median sternotomy and resected the tumor. The tumor was a solid, yellowish-brown mass measuring 42×42 mm. Pathologically, the tumor consisted mainly of chief cells with some oxyphil cells; there were no necrotic areas or nuclear atypia, and few mitotic figures. We diagnosed the tumor as an ectopic mediastinal parathyroid adenoma. Eight months after the resection, her serum calcium, phosphorus, and intact PTH levels were normal.
  
  
  CONCLUSIONS
  Parathyroid adenomas and parathyroid carcinomas have disparate natural histories, but they can be difficult to differentiate on the basis of preoperative clinical characteristics. We believe that long-term follow-up of these cases is required because there have been few reports on the postoperative natural history of large parathyroid adenomas.
authors.affiliation: Division of Thoracic and Cardiovascular Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. Electronic address: okura1127@gmail.com.
authors.forename: Seijiro
authors.initials: S
authors.lastname: Sato
authors.affiliation: Division of Thoracic and Cardiovascular Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kitahara
authors.affiliation: Division of Thoracic and Cardiovascular Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Terumoto
authors.initials: T
authors.lastname: Koike
authors.affiliation: Division of Thoracic and Cardiovascular Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Takehisa
authors.initials: T
authors.lastname: Hashimoto
authors.affiliation: Division of Cellular and Molecular Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Riuko
authors.initials: R
authors.lastname: Ohashi
authors.affiliation: Department of Pathology, the Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Motoi
authors.affiliation: Division of Thoracic and Cardiovascular Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Tsuchida
keywords: Ectopic parathyroid tumor; Hyperparathyroidism; Osteitis fibrosa cystica; Parathyroid adenoma