Learning Objective

Differentiate between dystrophic and metastatic calcification based on location, underlying cause, and associated clinical conditions.

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Types of Calcification

Calcium deposits appear deeply basophilic on H&E staining.

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Dystrophic Calcification

Definition:

Calcium deposition in abnormal or diseased tissues, regardless of serum calcium levels (which are normal).

Extent:

Usually localized.

Etiology:

Occurs secondary to tissue injury or necrosis.

Associated Conditions:

• Tuberculosis (lung, pericardium)
• Granulomatous infections
• Liquefactive necrosis in chronic abscesses
• Fat necrosis
• Infarcts
• Thrombi
• Schistosomiasis
• Congenital TORCH infections (CMV, toxoplasmosis, rubella)
• Psammoma bodies (papillary thyroid CA, meningioma, serous ovarian CA)
• CREST syndrome
• Calcified atherosclerotic plaques

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Metastatic Calcification

Definition:

Calcium deposition in normal tissues due to elevated calcium or phosphate levels.

Extent:

Usually widespread (diffuse).

Etiology:

Occurs secondary to hypercalcemia or hyperphosphatemia, such as:

• Chronic kidney disease (↑ phosphate)
• Primary hyperparathyroidism
• Sarcoidosis (↑ vitamin D activation)
• Hypervitaminosis D

Common Sites:

Occurs in tissues that rapidly lose acid, creating an alkaline environment that favors Ca²⁺ deposition:

• Kidney (collecting ducts → nephrocalcinosis → nephrogenic DI, renal failure)
• Lung
• Gastric mucosa

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