Parathyroid Hyperplasia

 

Epidemiology and Etiology:

    • Primary:
      • Adenoma (75-80%)
      • Diffuse or nodular hyperplasia (10-15%)
      • Parathyroid carcinoma (<5%)
      • F:M = 3:1
    • secondary:
      • chronic renal insufficiency
      • inadequate dietary intake of calcium
      • vitamin D deficiency
      • steatorrhea
    • tertiary:
      • chronic renal insufficiency

 

Common sites:

    •  metastatic calcification may be seen in primary or secondary hyperparathyroidism
      • lungs
      • heart
      • stomach
      • blood vessels

 

Gross features:

    • frequently assymetry in glandular involvement
      • but usually all are enlarged to some degree (in contrast to adenoma)
    • combined weight of all glands usually less than 1g

 

Histologic features:

    • chief cell hyperplasia
      • diffuse or multinodular
    • poorly-developed, delicate fibrous strands may envelop nodules
    • inconspicuous fat within gland (in contrast to normal parathyroid)
    • water-clear hyperplasia:
      • constituent cells with clear cytoplasm

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

 

 

 

 

Molecular features:

    •  familial:
      • MEN-1
      • MEN-2A
      • Familial Hypocalciuric Hypercalcemia (FHH)
        1. CASR mutations mostly
          1. mutations in parathyroid calcium-sensing receptor gene (CASR) on 3q
          2. homozygous mutations present neonatally
    • Sporadic:
      • MEN1 mutations
      • Monoclonal often

 

Other features:

    •  

 

References:

    • Robbins & Cotran Pathologic Basis of Disease (2005)