Histologic Patterns
What You'll Learn
- The recurring reactions the nervous system shows to any insult — recognize the pattern, then reach for the disease
- What each pattern looks like, the stain that confirms it, and what causes it
- The basic architectural patterns of neoplasia and the logic of grading
What You'll Learn
| Pattern | On the slide | Cause |
|---|
| Red (eosinophilic) neuron | Shrunken, bright-pink cytoplasm, pyknotic nucleus (H&E) | Acute ischemia/hypoxia (12–24 h) |
| Chromatolysis | Swollen soma, eccentric nucleus, Nissl dissolution | Axonal injury (axotomy) |
| Neuronophagia | Microglia engulfing a dying neuron | Viral infection, acute injury |
| Simple atrophy | Small dark neurons + gliosis, neuron loss | Chronic neurodegeneration |
What You'll Learn
| Pattern | On the slide | Cause / meaning |
|---|
| Reactive gliosis | Hypertrophic GFAP+ astrocytes (gemistocytes), glial scar | Any chronic CNS injury (the CNS “scar”) |
| Alzheimer type II astrocyte | Swollen pale nucleus, no cytoplasm | Hyperammonemia / hepatic encephalopathy |
| Rosenthal fibers | Eosinophilic corkscrew GFAP+ inclusions | Chronic gliosis, pilocytic astrocytoma, Alexander disease |
| Microglial nodule / rod cells | Clusters/rows of activated microglia | Viral encephalitis (HIV, CMV), neurosyphilis |
| Gitter cells (foamy macrophages) | Lipid-laden macrophages (LFB-PAS+, CD68+) | Infarct clean-up, active demyelination |
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