Intracellular%20Accumulation-2%20Pigments

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Intracellular Accumulation-2Pigments

• Dr Shoaib Raza

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Pigments

• They are colored substances
• Normal constituents of the cell
• Melanin
• Abnormal and accumulate only under special
  circumstances
• Endogenous
• Synthesize within the body
• Exogenous
• Coming from outside of the body

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Exogenous Pigments

• Carbon is the ubiquitous air pollutant of urban
  life
• Picked up by alveolar macrophages
• Through lymphatic channels to regional (Hilar)
  lymph nodes
• Causes blackening of the tissues of lung
  (Anthracosis)
• Anthracosis fibroblastic reaction Coal
  workers pneumoconiosis
• Tattooing is another exogenous pigment

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Endogenous Pigments

• Lipofuscin
• An insoluble pigment
• Wear-and-tear pigment
• Lipochrome
• Polymer of lipids phospholipids
• Complex with protein
• Derive through lipid peroxidation of
  polyunsaturated lipids of subcellular membrane
• Yellowish brown, finely granular, cytoplasmic
  (perinuclear) pigment
• Seen in cells undergoing slow regressive changes
• Liver heart of aging patients

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Melanin

• Endogenous, non hemoglobin derived brown black
  pigment
• Tyrosinase catalyzes oxidation of tyrosine in
  melanocytes
• It is the only endogenous brown black pigment
• Ochronosis
• Rare disorder seen in alkaptonuria,
• Black pigment deposit in skin, connective
  tissues, cartilage, etc.

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Hemosiderin

• Hb-derived golden yellow to brown, granular or
  crystalline pigment
• A major storage form of iron
• Iron transport via transferrin
• Iron apoferritin Ferritin micelles
• Excess of iron Hemosiderin
• Local excess (Common Bruises)
• Heme Biliverdin Bilirubin
• Systemic excess (Hemosiderosis)

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Hyaline Change

• The term usually refers to
• Intracellular or intercellular alteration that
  gives a homogenous, glassy, pink appearance in
  routine HE staining
• Histological term rather than a specific form of
  injury
• Intracellular accumulation of proteins
• Collagenous fibrous tissue in old scars
• Vessel wall in long standing hypertension

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Pathologic Calcification

• Abnormal tissue deposition of calcium salts
• Dystrophic calcification
• Deposition occur in the dead or injured tissue
• Necrosis, (Coagulative, liquefactive, caseous,
  fat)
• Atheroma and atherosclerosis
• Thrombus
• Aging or damaged heart valves
• Basophilic amorphous granular, sometimes clumped
  appearance
• Intracellular, extracellular or both
• Lamellated configuration psammoma bodies

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Pathogenesis of Dystrophic Calcification

• Ca is concentrated in the cells
• Ca binds to phospholipids of vesicle membrane
• Phosphate is added to the calcium
• Repeated cycle
• Structural change generate microvesicle of
  calcium and phosphate groups
• Dystrophic calcification is a sign of previous
  injury
• Often cause organ dysfunction

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Metastatic Calcification

• Occur in normal tissue whenever there is
  hypercalcemia
• Hyperparathyroidism
• Destruction of bone tissue
• Primary tumor of bone
• Metastatic tumors to bone
• Increase bone turnover
• Immobilization
• Vitamin D related disorders (Vitamin D
  intoxication)
• Renal failure

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Metastatic Calcification

• May occur widely throughout the body
• Interstitial tissue of gastric mucosa
• Kidney
• Lung
• Systemic arteries
• Pulmonary veins
• Morphology is similar to that of dystrophic
  calcification

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Aging

• Result of a progressive decline in cellular
  function and viability caused by genetic
  abnormalities, accumulation of cellular and
  molecular damage due to the effects of exposure
  to exogenous influences
• Genetic factors
• Diet
• Social condition
• Occurrence of age related disorders

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Contribution to Cell Aging

• Known changes that contribute to cell aging
• Decreased cellular replication
• Non-dividing state of cell, the senescence
• Telomere shortening
• Accumulation of metabolic and genetic damage
• Cell life span is determined by a balance between
  oxidative damage and molecular response for
  repair
• Ionizing radiation
• Mitochondrial dysfunction
• Reduction of antioxidant defense mechanism

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