Expansion
Dystrophic occurs in damaged tissue; metastatic occurs in normal tissue with high calcium
Expansion
Dystrophic calcification
- Occurs in damaged or dead tissue
- Serum calcium is normal
- Examples: atherosclerotic plaque, calcified heart valves, old tuberculous nodes, psammoma bodies in papillary thyroid and serous ovarian tumours, fat necrosis, breast microcalcification in ducts, old scars and infarcts
Metastatic calcification
- Occurs in normal tissue because of hypercalcaemia
- Deposits preferentially in tissues with an alkaline interstitium: gastric mucosa, kidney, lung, systemic arteries and cornea
- Causes: hyperparathyroidism, malignancy, vitamin D excess, chronic kidney disease, sarcoidosis, milk-alkali syndrome
The practical distinction is simple: check the serum calcium. Normal calcium with calcification means local tissue damage; raised calcium means a systemic disorder that must be identified.
Psammoma bodies are a useful subset to remember, being laminated calcified structures found in papillary thyroid carcinoma, serous papillary ovarian tumours, meningioma and mesothelioma.
Calciphylaxis is the severe form in renal failure, with calcification of small dermal vessels causing painful skin necrosis.