Parathyroid glands
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The parathyroid gland is an endocrine organ that is important in calcium regulation. It often makes an appearance in the context of thyroid surgery.
Normal
General
- Identification of normal can be tricky.
Gross
- No distinctive features - surgeons thus send 'em to pathologists.
Microscopic
Features:[1]
- 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[2] - key feature.
- Surrounded by a thin fibrous capsule.
- May vaguely resemble lymphoid tissue - may have hyperchromatic cytoplasm.
- High power:
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[5] to clear to eosinophilic[6].
- 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:
Parathyroid hyperplasia
- Parathyroid hyperplasia - classically assoc. with renal failure.
- Chief cell hyperplasia - associated with MEN I, MEN IIa.[7]
Parathryoid adenoma
MEN I:
- Parathyroid adenoma.
- Pancreatic neuroendocrine tumours.
- Pituitary adenoma.
MEN IIa/IIb (II/III):
- Parathyroid adenoma.
- Medullary thyroid carcinoma.
- Pheochromocytoma.
Image: Parathyroid adenoma (med.utah.edu).[8]
Parathyroid carcinoma
General
- Extremely rare.
See also
References
- ↑ http://www.medicalhistology.us/twiki/pub/Main/ChapterFourteenSlides/b56b_parathyroid_40x_he_labeled.jpg
- ↑ http://pathology.mc.duke.edu/research/Histo_course/parathyroid2.jpg
- ↑ http://www.bu.edu/histology/p/15002loa.htm
- ↑ http://dictionary.reference.com/search?q=oxyphil%20cell
- ↑ http://www.deltagen.com/target/histologyatlas/atlas_files/endocrine/parathyroid_and_thyroid_glands_20x.jpg
- ↑ http://instruction.cvhs.okstate.edu/Histology/HistologyReference/hrendo.htm
- ↑ URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970475-2. Accessed on: 29 July 2010.
- ↑ URL: http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/enfrm.html. Accessed on: 6 December 2010.