Accumulations and Deposits

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Accumulations and Deposits - Cellular Stash Secrets

  • Intracellular accumulation occurs via: abnormal metabolism, defective protein folding/transport, enzyme deficiency, or ingestion of indigestible materials.
  • Key Examples:
    • Lipids: Steatosis (e.g., fatty liver), cholesterolosis.
    • Proteins: Russell bodies (plasma cells), Mallory-Denk bodies (liver disease).
    • Glycogen: Diabetes mellitus, glycogen storage diseases (GSDs).
    • Pigments: Lipofuscin (wear & tear), melanin, hemosiderin (iron).
    • Calcium: Dystrophic (damaged tissue), metastatic (hypercalcemia).

⭐ Lipofuscin, the "wear-and-tear" pigment, is an insoluble brownish-yellow granular material accumulating in aging cells, particularly heart, liver, and brain. Lipofuscin granules in myocardial cells

Accumulations and Deposits - Fat, Protein Pile-Up

  • Fatty Change (Steatosis): Abnormal triglyceride accumulation in cells; often reversible.
    • Liver: Most common. Causes: Alcohol, toxins, DM, obesity, malnutrition.
      • Gross: ↑Size, yellow, greasy.
      • Micro: Fat vacuoles (can cause signet ring appearance). Stains: Oil Red O, Sudan Black B (frozen).
    • Heart: "Tigeroid" pattern (severe anemia, diphtheria). Liver steatosis with Oil Red O stain and signet ring cells
  • Protein Accumulation: Excess synthesis/uptake or defective folding/transport; often eosinophilic.
    • Examples:
      • Reabsorption droplets: Renal tubules (proteinuria).
      • Russell bodies: Ig in plasma cell RER (distended).
      • Mallory-Denk bodies: Cytokeratin in hepatocytes (alcoholic liver disease, NAFLD).
      • Neurofibrillary tangles: Alzheimer's (tau protein).
      • $\alpha$1-antitrypsin deficiency: Misfolded protein in liver ER.

    ⭐ Mallory-Denk bodies: Eosinophilic cytokeratin inclusions in hepatocytes (alcoholic hepatitis, NAFLD), appear as rope-like structures.

Accumulations and Deposits - Sugar & Stain Stories

  • Glycogen:
    • Excess intracellular glucose.
    • Causes: Diabetes (DM), Glycogen Storage Diseases (GSDs).
    • Sites: Liver, kidney (Armanni-Ebstein lesions in DM), heart.
    • Stain: PAS (+, magenta), diastase-sensitive.
    • Appearance: Clear cytoplasmic vacuoles.
  • Pigments (Endogenous):
    • Lipofuscin (Wear & Tear):
      • Yellow-brown granules; lipid peroxidation.
      • Sites: Heart, liver, brain (elderly).
      • Stain: Sudan Black B.
    • Melanin:
      • Brown-black; tyrosine oxidation.
      • Cells: Melanocytes.
      • Stain: Fontana-Masson (silver).
    • Hemosiderin (Iron):
      • Golden-yellow/brown; hemoglobin breakdown (ferritin aggregates).
      • Sites: Hemorrhage, chronic congestion.
      • Stain: Prussian blue (Perls') - iron blue.

      ⭐ Hemosiderin-laden macrophages in alveoli are "heart failure cells" (chronic pulmonary congestion).

    • Bilirubin (No Iron):
      • Yellow-green/brown; heme degradation.
      • Sites: Liver (jaundice, cholestasis).
      • Stain: Hall's (Fouchet) - bilirubin green.

Accumulations and Deposits - Outside Cell Overload

  • Amyloidosis: Extracellular deposition of misfolded fibrillar proteins (β-pleated sheets).

    • Stain: Congo Red → apple-green birefringence (polarized light).
    • Key Types:
      • AL: Ig light chains (plasma cell dyscrasias).
      • AA: Serum Amyloid A (chronic inflammation).
      • Aβ: APP (Alzheimer's disease plaques).
      • ATTR: Transthyretin (senile/familial amyloidosis).
    • Organs: Kidney (nephrotic syndrome), heart (restrictive cardiomyopathy), liver, spleen.

    ⭐ Congo Red stain showing apple-green birefringence under polarized light is pathognomonic for amyloidosis.

  • Pathologic Calcification: Abnormal Ca²⁺ salt deposition. Two types:

  • Gout: Monosodium Urate (MSU) crystal deposition in/around joints; from hyperuricemia.
    • Crystals: Needle-shaped, negatively birefringent. 📌 Mnemonic: Yellow when Parallel (YAP), Blue when Perpendicular (BUP) to compensator.
    • Tophus: Pathognomonic; MSU crystals + chronic granulomatous inflammation (macrophages, giant cells).

Amyloidosis: Apple-green birefringence with Congo Red stain

High‑Yield Points - ⚡ Biggest Takeaways

  • Steatosis: Reversible triglyceride accumulation, common in the liver.
  • Cholesterol: Accumulates in atherosclerosis, xanthomas, and cholesterolosis.
  • Lipofuscin: "Wear-and-tear" pigment from lipid peroxidation, linked to brown atrophy.
  • Hemosiderin: Iron-storage pigment, Prussian blue positive, indicates hemorrhage or iron overload.
  • Pathologic Calcification: Dystrophic in damaged tissue (normocalcemia); Metastatic with hypercalcemia.
  • Amyloidosis: Extracellular misfolded proteins; Congo Red stain shows apple-green birefringence.
  • Proteinopathies: Include Russell bodies (immunoglobulins) and Mallory-Denk bodies (cytokeratin).

Practice Questions: Accumulations and Deposits

Test your understanding with these related questions

Which type of necrosis is characterized by deposition of immune complexes and fibrin in the walls of blood vessels?

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Flashcards: Accumulations and Deposits

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_____ amyloidosis is characterized by systemic deposition of AA amyloid, which is derived from serum amyloid-associated protein (SAA)

TAP TO REVEAL ANSWER

_____ amyloidosis is characterized by systemic deposition of AA amyloid, which is derived from serum amyloid-associated protein (SAA)

Secondary

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Accumulations and Deposits - Free Indian Medical PG Review