Parathyroid glands

From Libre Pathology
Revision as of 15:37, 24 November 2011 by Michael (talk | contribs) (→‎Hypercalcemia DDx: subheading)
Jump to navigation Jump to search

The parathyroid glands are an endocrine organ that is important in calcium regulation. They often make an appearance in the context of thyroid surgery.

Clinical

Overview - hyperparathyroidism

Classification

  • Primary.
  • Secondary.
  • Tertiary.

Primary hyperparathyroidism

Cause:[1]

Familial causes of primary hyperparathyroidism:

  • MEN 1.
  • MEN 2.
  • Familial hypocalciuric hypercalcemia.
    • Autosomal dominant.
    • CASR (calcium sensing receptor) gene defect.[2]

Hypercalcemia DDx

Mnemonic GRIMED:[3]

  • Granulomatous disease (tuberculosis, sarcoidosis).
  • Renal disease.
  • Immobility.
  • Malignancy (esp. squamous cell carcinoma, plasmacytoma).
  • Endocrine (primary hyperparathyroidism, tertiary hyperparathyroidism, familial hypocalciuric hypercalcemia (FHH)).
  • Drugs (thiazides ... others).

Note:

  • Hyperparathyroidism and FHH are assoc. with an increased PTH.[4]
    • Other causes are assoc. with a decreased PTH.

Normal parathyroid glands

General

  • Identification of normal can be tricky.

Gross

  • No distinctive features - surgeons thus send 'em to pathologists.

Microscopic

Features:[5]

  • Low power:
    • May vaguely resemble lymphoid tissue - may have hyperchromatic cytoplasm.
      • Does not have follicular centres like a lymph node.
    • May form gland-like structure and vaguely resemble the thyroid at low power.
    • Cytoplasm may be clear[6] - key feature.
    • Surrounded by a thin fibrous capsule.
  • High power:
    • Mixed cell population:[7]
      • Chief cells - predominant cell type, small, cytoplasm has variable staining (hyperchromatic-clear-eosinophilic).
      • Oxyphil cells (acid staining cells[8]) - abundant cytoplasm.
      • Adipocytes - increased with age, may be used to help differentiate from thyroid - key feature.


Name Staining (cytoplasm) Quantity of cells Cytoplasm (quantity) Function
(parathyroid) chief cells intense hyperchromatic to eosinophilic (see note) abundant moderate manufacture PTH
oxyphil cells moderate/light hyperchromatic to eosinophilic rare abundant ?

Notes:

  • Cytoplasmic staining varies considerably on H&E preparations - it may vary from hyperchromatic[9] to clear to eosinophilic[10].
  • Chief cells tend to stain more intensely than oxyphil cells.

Thyroid vs. parathyroid (see: parathyroid image):

  • Parathyroid cytoplasm:
    • Hyperchromatic.

Parathyroid vs. lymphoid tissue (see parathyroid image):

  • Parathyroid:
    • No germinal centres.
    • Gland-like/follicular-like arrangement -- much smaller than normal follicles of
    • Occasional cell with rim of clear cytoplasm (oxyphil?).

Images:

Specific entities

Parathyroid hyperplasia

General

  • Chief cell hyperplasia - associated with MEN 1, MEN 2A.[11]
  • Parathyroid hyperplasia - classically assoc. with renal failure.
  • Classically all parathyroid glands are involved; however, some may be spared making it difficult to differentiate this from parathyroid adenoma.[12]

Microscopic

Features:[12]

  • Similar to parathyroid adenoma.
  • +/-Water-clear cells ("water-clear cell hyperplasia").

Parathyroid adenoma

General

  • One parathyroid is big... the others are small.
  • Associated with MEN I and MEN IIa/b (II/III).

MEN I:

MEN IIa/IIb (II/III):

Image: Parathyroid adenoma (med.utah.edu).[13]

Microscopic

Chief cell adenoma

Features:[1]

  • Chief cells:
    • Small central nucleus.
    • Moderate cytoplasm.
  • +/-Scattered oxyphil cells:
    • Large cells.
    • Abundant cytoplasm.

Image:

Oxyphil adenoma

Features:[1]

  • Oxyphil cells:
    • Large cells.
    • Abundant cytoplasm.

DDx:

Parathyroid carcinoma

General

  • Extremely rare.

Microscopic

Features:[14]

  • Histologically normal parathyroid cells.
    • Cytologic features not reliable for diagnosis.
  • Fibrous capsule.
  • Invasion of surrounding tissue - key feature.
  • +/-Metastasis - diagnostic feature.

Note:

  • Diagnosis of parathyroid carcinoma is like that of malignant pheochromocytoma - cytology useless, tissue invasion and metastases are the key features.

Image:

See also

References

  1. ↑ 1.0 1.1 1.2 Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1127. ISBN 978-1416031215.
  2. ↑ Online 'Mendelian Inheritance in Man' (OMIM) 601199
  3. ↑ TN06 Emerg.
  4. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1129. ISBN 978-1416031215.
  5. ↑ http://www.medicalhistology.us/twiki/pub/Main/ChapterFourteenSlides/b56b_parathyroid_40x_he_labeled.jpg
  6. ↑ http://pathology.mc.duke.edu/research/Histo_course/parathyroid2.jpg
  7. ↑ http://www.bu.edu/histology/p/15002loa.htm
  8. ↑ http://dictionary.reference.com/search?q=oxyphil%20cell
  9. ↑ http://www.deltagen.com/target/histologyatlas/atlas_files/endocrine/parathyroid_and_thyroid_glands_20x.jpg
  10. ↑ http://instruction.cvhs.okstate.edu/Histology/HistologyReference/hrendo.htm
  11. ↑ URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970475-2. Accessed on: 29 July 2010.
  12. ↑ 12.0 12.1 Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1128. ISBN 978-1416031215.
  13. ↑ URL: http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/enfrm.html. Accessed on: 6 December 2010.
  14. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1128. ISBN 978-1416031215.
Retrieved from "https://librepathology.org/w/index.php?title=Parathyroid_glands&oldid=9878"