Parathyroid adenoma

Parathyroid adenoma
Diagnosis in short
Chief cell parathyroid adenoma (left of image) and unremarkable parathyroid gland (right of image). H&E stain. (WC)
LM	proliferation of parathyroid cells (chief cells, oxyphils or both) usually lacking adipose tissue, +/-rimmed by normal parathyroid gland, lack of destructive invasion of surround structures, lack of metastatic disease
Subtypes	chief cell, oxyphil, mixed
LM DDx	parathyroid hyperplasia, parathyroid carcinoma, lymph node, thyroid gland, Hürthle cell adenoma of thyroid (for oxyphil subtype)
IHC	Ki-67 low
Site	parathyroid gland (neck/mediastinum)
Associated Dx	renal stones, osteitis fibrosa cystica
Syndromes	multiple endocrine neoplasia 1, multiple endocrine neoplasia 2A
Signs	constipation
Symptoms	bone pain, abdominal pain, lethargy, fatigue, memory loss
Blood work	increased parathyroid hormone, serum calcium increased
Prognosis	benign
Other	depression, psychosis, delirium, coma, ataxia
Clin. DDx	nodule (lymph node, other tumours), hyperparathyroidism (parathyroid hyperplasia, parathyroid carcinoma), DDx of hypercalcemia
Treatment	surgical excision

Parathyroid adenoma is a common benign pathology of the parathyroid gland.

General

• Clinical diagnosis - significant intraoperative drop of PTH after removal of suspected adenoma.
• Most common cause of primary hyperparathyroidism.
• May be associated with MEN 1 or MEN 2A.

MEN 1:

• Parathyroid adenoma.
• Pancreatic neuroendocrine tumour.
• Pituitary adenoma.

MEN 2A:

• Parathyroid adenoma.
• Medullary thyroid carcinoma.
• Pheochromocytoma.

Subtypes

Histologic subtyping:

1. Chief cell parathyroid adenoma.
   • Common.
2. Oxyphil parathyroid adenoma.
   • Uncommon.
3. Mixed.

Gross

• One parathyroid gland is big... the others are small.

Microscopic

Features:

• Proliferation of parathyroid cells (chief cells, oxyphils or both) usually intermixed lacking adipose tissue.
• +/-Rim of normal parathyroid gland around the lesion with adipose tissue.

Note:

• Generally, it is impossible to discern between parathyroid adenomas and parathyroid hyperplasias by histology alone.
  • One requires information of the size of the other glands to make the diagnosis.

DDx:

• Parathyroid hyperplasia - differentiated by clinical history.
• Parathyroid carcinoma - destructive invasion of surrounding tissue or far away mets, increased proliferative activity.
• Lymph node.
• Hürthle cell adenoma - for oxyphil type (see below).
• Thyroid gland.

Chief cell parathyroid adenoma

Features:

• Chief cells - key feature:
  • Small central nucleus.
    • Round with stippled chromatin - important.
  • Moderate cytoplasm.
• +/-Scattered oxyphil cells:
  • Large cells.
  • Abundant cytoplasm.
• Architecture:
  • Nests.
  • Circular formations - often around capillaries (perivascular pseudorosettes).

Images

• 

  Parathyroid adenoma - low mag. (WC/Nephron)

• 

  Parathyroid adenoma - high mag. (WC/Nephron)

Oxyphil parathyroid adenoma

Features:

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

DDx:

• Hürthle cell adenoma of the thyroid gland.

Image

• 

  PA, mixed type - high mag.

• 

  PA, mixed type - very high mag.

• 

  Oxyphil cells - high mag.

www:

• Parathyroid adenoma (med.utah.edu).

Sign out

Note:

• One should not say "negative for malignancy".

Parathyroid Gland, Excision:
- Chief cell parathyroid adenoma.

Parathyroid Gland, Excision:
- Chief cell parathyroid adenoma with adjacent normal parathyroid tissue.

Parathyroid Gland (Submitted as "Right Superior Parathyroid Adenoma"), Excision:
- Parathyroid adenoma with adjacent normal parathyroid tissue.

Tertiary hyperparathyroidism

A. Right Inferior Parathyroid, Excision:
- Cellular parathyroid tissue with a rim of normal-appearing 
  parathyroid tissue, compatible with parathyroid adenoma.

B. Portion of Right Superior Parathyroid, Excision:
- Cellular parathyroid compatible with adenoma or hyperplasia.

Unclear history

Submitted as "Right Inferior Parathyroid", Excision:
- Hyperplastic appearing parathyroid tissue devoid of fat consisting of a
  mixture of chief cells and oncocytic cells, compatible with parathyroid 
  adenoma in proper clinical context.
- Unremarkable parathyroid tissue.

Block letters

PARATHYROID GLAND, EXCISION:
- CHIEF CELL PARATHYROID ADENOMA.

Micro

The section shows an adenoma consisting predominantly of chief cells. A rim of normal parathyroid is seen adjacent to the adenoma. A small amount of unremarkable adipose tissue is present.

See also

• Parathyroid glands.