Pathologic Calcification- Basic Pathology

 Definition

♦ It is the abnormal tissue deposition of calciums salts together with smaller amount of iron, magnesium and other mineral salts.

Pathologic Calcification in Arterial Wall

♦ Two types:

• Dystrophic calcification
• Metastatic calcification

Dystrophic calcification

♦ It is seen in areas of necrosis (coagulative, caseous or liquefactive or fat necrosis)

♦ It occurs in dying tissues despite normal serum levels of calcium and in absence of derangements in calcium metabolism.

 Two types of causes are seen:

A. Calcification in dead tissues:

i. Caseous necrosis in T.B.
ii. Liquefaction necrosis in chronic abscess.
iii. Fat necrosis in acute pancreatitis or traumatic
fat necrosis in breast.
iv. Gamma–gandy bodies in chronic venous
congestion
v. Infarcts.
vi. Thrombi especially in veins.
vii. Dead parasites eg: In hydatid cysts.
viii. Calcification in breast cancer.
ix. Congential toxoplasmosis.

B. Calcification in degenerated tissues:

i. Dense old scars.
ii. Atheromas in aorta (calcification is almost
always present)
iii. Stroma of tumors such as fibroids, breast
cancer.
vi. Cysts eg. Epidermal cysts.

Mechanism:

Calcium ions binds to phospholipids present in
vesicle membrane.
↓
Phosphatases associated with membrane
generate phosphate groups.
↓
Phosphate groups bind to calcium.
↓
Cycle of calcium & phosphate binding is
repeated
↓
Deposit is formed near membrane.
↓
Structural change occurs in arrangement of
calcium & phosphate group.
↓
Microcrystal is formed (crystalline calcium
phosphates)
↓
Propagate leading to more calcium deposition.

Morphology:

Gross:

• Calcium salts appear as fine, with granules or clumps(Gritty deposits).

Microscopy

Photomicrograph of Dystrophic Calcification

• Calcium salts have basophilic, amorphous, granular appearance.
• Can be intracellular or extracellular
• lamellated configuration called as psammoma bodies may be seen.

Metastatic Calcification:

• It occurs in normal tissue due to hypercalcemia.

Causes are:

i. Excessive mobilization of calcium from the bone:

• Hyperparathyroidism.
• Bony destruction.
• Prolonged immobilisation

ii. Excessive absorption of calcium from gut:

• Hypervitaminosis D
• Milk alkali syndrome
• Hypercalcemia of infancy.

Most commonly affected organs are: kidney, lungs, stomach, blood vessels, cornea, synovium.

Mechanism:

Tissues excrete acid

↓

Create an internal alkaline compartment.

↓

Favour calcification

Morphology:

• Morphology resembles that of dystrophic calcification.

• May occur as non-crystalline amorphous deposit or as hydroxyapatite crystals.

Differences Between Dystrophic and Metastatic Calcification

Differences between Dystrophic Calcification and Metastatic Calcification

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