Parathyroid gland
Neoplasms
Parathyroid adenoma

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 12 April 2018, last major update January 2013

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Parathyroid adenoma[TI] pathology free full text[sb]

Cite this page: Roychowdhury, M. Parathyroid adenoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/parathyroidpthadenoma.html. Accessed May 21st, 2018.
Definition / general
  • Usually monoclonal but hyperplastic glands may also be monoclonal
  • Difficult to diagnose - best criterion is lack of hypercalcemia for 5 years after excision
  • Remaining glands usually normal in size or shrunken due to feedback inhibition from elevated serum calcium (presence of microscopically normal second gland strongly suggests that parathyroid lesion is an adenoma); 10% of patients show minimal hyperplasia in remaining glands
Epidemiology
  • Demographics: 75% women, usually in 30s, solitary lesions, functionally active, clonal
Clinical features
Case reports
Clinical images

Images hosted on other servers:

Various images of parathyroid gland and adenoma

Gross description
  • Solitary, 0.5 - 5.0 g, well circumscribed tan nodule with delicate capsule
  • May undergo cystic change or hemorrhage
  • May have rim of normal tissue
Gross images

Images hosted on PathOut server:

Contributed by Dr. Mona Kandil, Menoufiya University, Egypt:

Various images



Images hosted on other servers:

Fig C: red-brown mass within the cystic lesion

Right: parathyroid adenoma;
left: thymoma

Microscopic (histologic) description
  • Encapsulated, cellular, homogenous lesions, rarely papillary, composed of chief cells with some oxyphil cells in delicate capillary network
  • Microfollicles resembling those in thyroid are common
  • May see rim of compressed normal tissue if adenoma is very large
  • Adipose tissue is rare (Am J Surg Pathol 1988;12:282)
  • Minimal mitotic activity
  • May see clusters of bizarre nuclei (also seen in other benign endocrine tumors)
  • Large tumors often display hemorrhage, cholesterol clefts, fibrosis
  • Usually no capsular invasion, no vascular invasion, no invasion of adjacent tissue
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Dr. Mona Kandil, Menoufiya University, Egypt:

Various images



Images hosted on other servers:

Fig B: FNA shows
elongated nuclei
and nuclear groove;
D: histologic section

Adenoma with rim of
normal parathyroid
tissue and small benign
parathyroid cyst

Rim of normal parathyroid
tissue admixed with adipose
tissue cells compressed to
lower edge of adenoma

Electron microscopy description
  • Long cytoplasmic processes (microvilli) extending into wide intercellular spaces are associated with high serum calcium (17.5 mg/dl) vs. relatively straight plasmalemma with interdigitations and narrow intercellular spaces, associated with moderately elevated calcium (mean 12.4 mg/dl)
  • High serum calcium case also had numerous nuclear pores and annulate lamellae but inconspicuous Golgi apparatus (Hum Pathol 1985;16:511)
Molecular / cytogenetics description
Differential diagnosis