Brown atrophy is due to accumulation of - Anonymous Quiz 58 answers π Melanin: 3 (5%) π Hemosiderin: 32 (55%) π Hematin: 3 (5%) β Lipofuscin: 20 (34%)
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The answer is confirmed. Here is a complete explanation:
Brown Atrophy - Answer: Lipofuscin β
The quiz answer is correct - the majority who chose Hemosiderin (55%) were wrong. The right answer is Lipofuscin (34%).
What is Lipofuscin?
Lipofuscin is the "wear-and-tear pigment" - an insoluble brownish-yellow granular intracellular material. As Robbins Basic Pathology defines it:
"Lipofuscin represents complexes of lipid and protein produced by the free radical-catalyzed peroxidation of polyunsaturated lipids of intracellular membranes. It is a marker of past free radical injury but is not injurious to the cell. When present in large amounts, the brown pigment imparts an appearance to the atrophic tissue..."
This appearance is exactly what is called brown atrophy.
Key Facts About Brown Atrophy
| Feature | Detail |
|---|---|
| Pigment | Lipofuscin |
| Primary organs affected | Heart, liver, brain |
| Mechanism | Free radical-catalyzed peroxidation of polyunsaturated membrane lipids |
| Trigger | Aging (senile atrophy) or pathologic atrophy (e.g., cachexia) |
| Gross appearance | Organ is shrunken and brown |
| Histology | Perinuclear golden-brown granules in cytoplasm |
| Effect on cell | Non-injurious (just a marker of past injury) |
Why the Other Options Are Wrong
- Melanin: A skin/eye pigment produced by melanocytes; not responsible for brown atrophy
- Hemosiderin: An iron-storage pigment formed from hemoglobin breakdown (e.g., in old hemorrhages, hemochromatosis); gives a golden-yellow to brown colour but causes hemosiderosis/hemochromatosis, not brown atrophy
- Hematin: A breakdown product of hemoglobin; seen in malaria (malaria pigment/hemozoin) and not linked to atrophy
Classic Clinical Scenarios for Brown Atrophy
- Cardiac brown atrophy: Seen in elderly patients and severe cachexia (cancer, starvation) - the heart shrinks and turns brown due to lipofuscin accumulation in cardiomyocytes
- Hepatic brown atrophy: Similar mechanism in the liver
- Robbins & Kumar Basic Pathology, p. 725-731; Robbins, Cotran & Kumar Pathologic Basis of Disease
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