Neuropathology — MCQs

Q: The following brain biopsy of patient who presented with marked psychomotor agitation is diagnostic of?

Rabies encephalitis. ***Correct: Rabies encephalitis*** - The brain biopsy showing **Negri bodies** (pathognomonic eosinophilic intracytoplasmic inclusions in pyramidal neurons of hippocampus and Purkinje cells of cerebellum) is diagnostic of **rabies encephalitis** - Clinical presentation of **marked psychomotor agitation** is characteristic of the furious form of rabies - Histopathology shows **perivascular lymphocytic cuffing** and neuronal degeneration along with Negri bodies - Rabies is caused by a **neurotropic RNA rhabdovirus** transmitted through animal bites *Incorrect: Herpes simplex encephalitis* - HSV encephalitis primarily affects the **temporal lobes** (hemorrhagic necrotizing encephalitis) - Histology shows **Cowdry type A intranuclear inclusions**, not cytoplasmic Negri bodies - Clinical features include fever, altered sensorium, and temporal lobe signs (olfactory/gustatory hallucinations) *Incorrect: Creutzfeldt-Jakob disease* - CJD is a **prion disease** showing **spongiform changes** (vacuolation) in the brain parenchyma - No viral inclusion bodies are seen - Clinical presentation includes rapidly progressive dementia, myoclonus, and ataxia *Incorrect: Japanese encephalitis* - JE causes **basal ganglia and thalamic involvement** (seen on neuroimaging) - Histology shows **neuronal necrosis and neuronophagia** but no characteristic inclusion bodies like Negri bodies - Clinical features include parkinsonian features and movement disorders *Incorrect: Acute disseminated encephalomyelitis* - ADEM is a **post-infectious demyelinating disease** showing perivenular demyelination - Histology shows demyelination with preservation of axons, not viral inclusions - Usually follows viral infection or vaccination

Q: A patient presents with unilateral painless proptosis. Biopsy shows which of the following?

Schwannoma. ***Schwannoma*** - **Schwannomas** are common causes of **unilateral painless proptosis** when they arise from nerves within the orbit [2]. - Biopsy typically shows **Antoni A** and **Antoni B areas**, with Verocay bodies [1]. *Neurofibroma* - While neurofibromas can occur in the orbit, they are more commonly associated with **Neurofibromatosis type 1** and often present as diffuse plexiform lesions [2]. - Histologically, they are characterized by a mix of **Schwann cells**, fibroblasts, and perineurial-like cells in a myxoid matrix, lacking the distinct Antoni A/B patterns. *Rhabdomyoma* - **Rhabdomyomas** are benign tumors of **striated muscle** and are rare in the orbit. - They are more commonly found in the **heart** (associated with tuberous sclerosis) or head and neck region. *Leiomyoma* - **Leiomyomas** are benign tumors of **smooth muscle** and are extremely rare in the orbit, as the orbit contains very little smooth muscle. - They are more commonly found in the **uterus** (fibroids) or gastrointestinal tract. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, p. 1250. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1248-1249.

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Parkinson's disease pathology

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Amyotrophic lateral sclerosis

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Primary CNS tumors

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Metastatic CNS tumors

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Peripheral nerve disorders

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Skeletal muscle diseases

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