BASIC NEUROPATH

Question 1

WHAT STRUCTURE?

Answer 1

A. Vacuolated swollen motor neuron in medulla.

B. Chronic atrophy of pyramidal neuron: The perikaryon is shrunken, the dendrites are corkscrew-like, and the nucleus is densely basophilic.

C. Axonal or retrograde changes in hypoglossal neuron caused by tumorous infi ltration of the nerve roots. The swollen perikaryon is rounded, the dendrites are retracted, the Nissl bodies are partially dissolved, and remaining ones are clustered around the peripherally displaced nucleus (hematoxylin-

eosin [HE] stain).

Question 2

WHAT STRUCTURES

Answer 2

D. Ischemic Purkinje cells in the cerebellar cortex showing eosinophilic shrunken perikaryons and homogenous basophilic nuclei (HE).

E. Spinal motor storage neuron in Tay-Sachs disease; the cytoplasm is markedly distended and the nucleus displaced to the periphery

Question 3

Answer 3

Neurofi brillary tangles in Alzheimer’s disease (Gallyas silver stain)

Question 4

Answer 4

positive immunostaining for tau protei

Answer 5

Pick bodies in pyramidal neurons of hippocampus in (Bodian silver stain

Question 6

Answer 6

Lewy body in substantia nigra in Parkinson’s disease

Question 7

Answer 7

Hirano body in pyramidal neuron of hippocampus

Question 8

Answer 8

Axonal degeneration. (A) Fusiform swelling and (B) disintegration of axon into small argyrophilic fragments (Holmes stain).

Question 9

Answer 9

C. Beta-amyloid precursor protein (β-APP) immunoreaction of injured axons (immunostain

Question 10

Answer 10

D. Axonal spheroids in traumatic

injury (Holmes stain) E. Fusiform enlargement of the axon (torpedo) of a degenerated Purkinje cell (Bodian stain).

Question 11

Answer 11

B. Fibrillary astrocytes display numerous short, fi ne processes and one long

process attached to the capillary wall with a foot plate (Cajal gold stain

Question 12

Answer 12

Astrocytes. A. Protoplasmic astrocytes. Cerebral cortex shows oval and round astrocytic nuclei with moderate amount of chromatin and prominent nucleoli (Cresyl violet

Question 13

Answer 13

C. Positive immunostaining for glial fi brillary acidic

protein (GFAP).

Answer 14

Pathology of astrocytes. A. Gemistocytic (reactive) astrocytes display a large eosinophilic glassy cytoplasm with short processes and a peripherally displaced nucleus (HE

Question 15

Answer 15

B. Fibrillary astrogliosis beneath the pia mater. Fibrous astrocytes showing numerous fi ne fi brillated processes (Holzer stain).

Question 16

Answer 16

C. Alzheimer’s type 2 astrocytes display a large vesicular nucleus with scanty chromatin

and a prominent nucleolus (HE).

Question 17

Answer 17

D. Rosenthal fi bers in an astrocytoma appear as eosinophilic rod-shaped, homogenous structures

(HE).

Question 18

Answer 18

E. Corpora amylacea around blood vessels (HE). F. Argyrophilic astrocytic plaque in cortical basal degeneration

(Gallyas). G. Bergmann astrocytes replace degenerated Purkinje cells in cerebellar cortex (HE).

Question 19

Answer 19

Oligodendrocytes. A. Satellite oligodendrocytes around cortical neurons (HE). B. Interfascicular oligodendrocytes along myelin sheaths (LFB-CV). Oligodendrocytes showing (C) argyrophilic cytoplasmic inclusions in multiple system atrophy (Gallyas

stain).

Question 20

Answer 20

Ependymal glia. Cuboidal epithelial cells cover the ventricular

surface and small nodules of proliferated astrocytes project

into the ventricular lumen (granular ependymitis) (HE).

Question 21

Answer 21

Microglia.

A. Resting microglia showing small elongated nucleus, scanty cytoplasm, and bipolar processes (Hortega silver stain).

B. Activated rod-shaped microglia in encephalitis.

C. Macrophages showing large, round, foamy cytoplasms and small eccentric

nuclei (HE).

Question 22

Answer 22

Myelin.

A. Schematic drawing of axons, myelin sheaths, and oligodendrocytes.

B. Light microscopic picture showing longitudinally oriented myelin sheaths (stained blue) along nerve fi bers (stained black; Holmes stain).

C. Swelling and breaking up of myelin sheaths (LFBeosin).

D. Disintegration of myelin into small oil-red O-positive lipid

globules.

Question 23

WHAT DEGENRATION?

Answer 23

Anterograde or Wallerian degeneration.

A. Lacunar infarct in the internal capsule.

B. Degeneration of the ipsilateral pyramidal tract in the medulla (myelin stain).

C. MRI of a 68-year-old man showing an old infarct in distribution of middle cerebral artery. Note the atrophy of the ipsilateral pedunculus due to wallerian degeneration of the descending corticopontine and pyramidal

tracts.

Question 24

WHAT PROCESS IS SHOWN?

Answer 24

Histology of vasogenic edema.

A. Macrosection of the hemispheric white matter shows loss of affi nity of myelin for Luxol fast blue. The arcuate fi bers are relatively preserved.

B. Extravasated plasma infi ltrates the white matter and the pericapillary spaces.

C. The white matter is vacuolated and spongy, and the myelin sheaths are separated from each other and are broken up (LFBCV).

D. Hypertrophied GFAP-positive astrocytes are noted in spaces between the myelin sheaths (immunostains

Question 25

WHAT PHYSIOLOGIC PROCESS?

Answer 25

Cerebral changes in physiologic aging.

A. MRI showing periventricular caps around the anterior horns.

B. Lipofuscin accumulation in thalamic neuron in the brain of a 73-year-old man (HE).

C. Neuritic plaque in hippocampus (Bodian stain).

D. Abundance of corpora amylacea in the pia matter (immunostain for ubiquitin).

E. Siderocalcinosis of small blood vessel in basal

ganglia (HE).