Subtitle: A complete, exam-oriented review of reversible cell injury based on Robbins, focusing on hydropic change, fatty change, and high-yield pathology concepts.

Author: PathologyMCQ Team
Category: General Pathology
Read Time: 6 minutes

At a Glance

• Core mechanisms: ATP depletion, ion pump failure, hydropic change
• Morphological features: cellular swelling, membrane blebs, fatty change
• Includes high-yield MCQs with detailed explanations

Contents

1. Introduction
2. What Is Reversible Cell Injury?
3. Mechanism of Reversible Injury (ATP Depletion Pathway)
4. Morphology of Reversible Injury
5. Practice Quiz
6. Key Takeaways
7. Recommended Learning
8. Reference

1.Introduction

Reversible cell injury represents the earliest and mildest form of cellular damage, during which the cell maintains the ability to return to normal structure and function once the stressor is removed. This concept is fundamental in general pathology and serves as the foundation for understanding how tissues respond to ischemia, toxins, metabolic disturbances and physical injury.

The two hallmark patterns of reversible injury are:

• Hydropic change (cellular swelling)
• Fatty change (steatosis)

These modifications result from ATP depletion, ion pump failure, and early cytoplasmic and organelle derangements, all of which remain reversible if promptly corrected.

2.What is Reversible cell injury?

Reversible injury occurs when the cell experiences sublethal stress that does not damage the nucleus irreversibly.

Key Characteristics

• Increased cellular water content (hydropic change)
• Plasma membrane blebbing
• Mitochondrial swelling without density body formation
• Dilation of rough endoplasmic reticulum (RER)
• Detachment of polysomes → reduced protein synthesis
• Fatty change, especially in liver and myocardium

3.Mechanism of reversible cell injury

The central event in reversible injury is ATP depletion, typically from hypoxia, mitochondrial dysfunction or toxins.

Sequence of Events

1. ↓ ATP production
2. Impaired Na⁺/K⁺ ATPase → Na⁺ accumulates inside
3. Water influx → cellular swelling
4. Detachment of ribosomes → ↓ protein synthesis
5. ER dilation
6. Cytoskeletal disruption → membrane blebs

When the stimulus is removed early, the cell restores normal homeostasis.

4.Morphology of reversible injury

Light Microscopy

• Cell swelling
• Pale cytoplasm
• Increased turgor
• Vacuolation (hydropic change)
• Fatty vacuoles in liver/heart

Ultrastructure

• Membrane blebs
• RER dilation with ribosomal detachment
• Mitochondrial swelling (mild)
• Formation of myelin figures (from damaged membranes)

5.High – yield MCQS

6.Key Takeaways

• Reversible cell injury is defined by cell swelling and fatty change
• Central mechanism: ATP depletion → ion pump failure
• Ultrastructural hallmark: ER dilation with ribosomal detachment
• Nuclear changes = NOT reversible

7.Recommended learning

8.Reference

• Robbins & Cotran: Pathologic Basis of Disease
• WHO Classification of Tumours (Latest Editions)
• Standard general pathology teaching resources