title: Primary and metastatic parathyroid malignancies: a rare or underdiagnosed condition?
abstract: OBJECTIVE
  Parathyroid gland malignancies are considered rare. The most common of these tumor types is primary parathyroid carcinoma. Metastatic spread from other cancers may also occur with up to 10% of cancers from other sites showing parathyroid involvement at autopsy. Tumor-to-tumor metastases (metastatic spread to parathyroid neoplasm) from remote cancers to the parathyroid gland have been described.
  
  
  METHODS
  We did a PubMed literature review and analysis of our own experience of 392 consecutive parathyroidectomies.
  
  
  RESULTS
  Primary and secondary parathyroid malignancies can be grouped into three categories: primary parathyroid carcinoma (PPCa), spread of carcinoma into parathyroid glands by contiguous extension from the thyroid gland or other head and neck cancer, and metastatic disease to the parathyroid gland from distant cancers. Studies of tumor-to-tumor spread indicate a predilection of spread to endocrine tumors possibly because of the rich blood supply that is present in endocrine tumors. Two of our 392 parathyroidectomies (0.5%) had cancer: one metastatic (thymic neuroendocrine tumor) and another PPCa.
  
  
  CONCLUSIONS
  Metastatic disease to the parathyroid gland is poorly documented. When performing surgery for primary thyroid cancer, the search for parathyroid gland metastases is often overlooked because of the desire to preserve parathyroid function. Metastatic disease from other cancers to a benign parathyroid gland or to a parathyroid adenoma probably suggests a grave prognosis because it likely indicates widespread metastatic disease; however, isolated metastases to the parathyroid may occur. Although these lesions may be uncommon they may not be as rare as once thought.
authors.affiliation: Department of Surgery (A.S., J.D.), Jersey Shore University Medical Center, Neptune, New Jersey 07754; Department of Pathology (V.L.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104; Endocrinology Center of New Jersey (S.S.-D.), Red Bank, New Jersey 07701; and Department of Pathology (M.Z., B.E., T.M.), Jersey Shore University Medical Center, Neptune, New Jersey 07754.
authors.forename: Alexander
authors.initials: A
authors.lastname: Shifrin
authors.forename: Virginia
authors.initials: V
authors.lastname: LiVolsi
authors.forename: Svetlana
authors.initials: S
authors.lastname: Shifrin-Douglas
authors.forename: Min
authors.initials: M
authors.lastname: Zheng
authors.forename: Brian
authors.initials: B
authors.lastname: Erler
authors.forename: Theodore
authors.initials: T
authors.lastname: Matulewicz
authors.forename: John
authors.initials: J
authors.lastname: Davis
mesh_terms: D002277:Carcinoma / Q000175:diagnosis* / Q000453:epidemiology* / Q000473:pathology; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D009362:Neoplasm Metastasis; D010282:Parathyroid Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000556:secondary; D012189:Retrospective Studies