Pathology Ch 27 Peripheral Nerves and Skeletal Muscles

Question 1

What is the dominant histopathologic finding in Immune mediated neuropathies like Guillain- Barre Syndrome?

Answer 1

Inflammation of peripheral nerve, manifested as perivenular and endoneurial infiltration by lymphocytes, macrophages, and a few plasma cells(TOPNOTCH)

Question 2

What is the most common type of peripheral neuropathy seen in adult-onset DM?

Answer 2

Symmetric neuropathy that involves distal sensory and motor nerves (TOPNOTCH)

Question 3

In patients with peripheral neuropathy, what is the predominant histologic findings?

Answer 3

Axonal neuropathy (TOPNOTCH)

Question 4

Morphology: Perifascicular Atrophy

Answer 4

Dermatomyositis (TOPNOTCH)

Question 5

Morphology: presence of rimmed vacuoles within myocytes and are highlighted by basophilic granules at their periphery. In addition, the vacuolated fibers may also contain amyloid deposits that stain with Congo Red.

Answer 5

Inclusion body myositis (TOPNOTCH)

Question 6

Morphology: Panfascicular atrophy

Answer 6

Spinal Muscular Atrophy (Infantile Motor Neuron Disease (TOPNOTCH)

Question 7

What are the 5 histopathologic abnormalities common to Duchenne Muscular Dystrophy and Becker Muscular Dystrophy?

Answer 7

1. Variation in fiber diameter
2. Increased numbers of internalized nuclei
3. Degeneration, necrosis, and phagocytosis of muscle fibers
4. Regeneration of muscle fibers
5. Proliferation of endomysial connective tissue (TOPNOTCH)

Question 8

Morphology: In later stages of this disease, all muscles eventually become almost totally replaced by fat and connective tissue

Answer 8

DMD (TOPNOTCH)

Question 9

What is the histologic pathology that is usually seen in DMD and is rare in BMD?

Answer 9

Enlarged, rounded, hyaline fibers that have lost their normal cross striation, believed to be hypercontracted fibers (TOPNOTCH)

Question 10

Morphology: Ring fiber ( subsarcolemmal band of cytoplasm that appears distinct from the center of the fiber) and Sarcoplasmic mass

Answer 10

Myotonic Dystrophy (TOPNOTCH)

Question 11

Morphology: Disuse changes with Type 2 fiber atrophy, post synaptic membrane is simplified, with loss of AChRs from the region of the synapse. Immune complexes as well as the MAC of the complement cascade can be found along the post synaptic membrane as well

Answer 11

Myesthenia Gravis (TOPNOTCH)

Question 12

Electron Microscopy: tubular and filamentous inclusions are seen in the cytoplasm and the nucleus, and they are composed of B-amyloid or hyperphosphorylated tau.

Answer 12

Inclusion body myositis (TOPNOTCH)

Question 13

Grotton lesions (scaling erythematous eruption or dusky red patches over the knuckles, elbows, and knees) are seen in what disease entity?

Answer 13

Dermatomyositis (TOPNOTCH)

Question 14

Morphology: the most consistent pathologic finding in skeletal muscle is aggregates of abnormal mitochondria that stain with modified Gomori Trichrome and fiber appears irregular on cross section “ragged red fibers” and on electron microscope, they contain “parking lot inclusions”

Answer 14

Mitochondrial Myopathies (Oxidative phosphorylation Disease) (TOPNOTCH)

Question 15

This is general reaction of the motor unit which is a result of primary destruction of the axon, with secondary disintegration of its myelin sheath.

Answer 15

Axonal degereration (TOPNOTCH)

Question 16

This general reaction of the motor unit occurs when there is dysfunction of the Schwann cell or damage to the myeling sheath; there is no primary abnormality of the axon

Answer 16

Segmental demyelination (TOPNOTCH)

Question 17

Morphology: endoneurial arterioles show thickening, hyalinization, and intense PAS positivity in their walls and extensive reduplicaton of the basement membrane.

Answer 17

Peripheral Neuropathy in DM Type 2 (TOPNOTCH)

Question 18

Of all the dystrophies, this type is the only one that shows pathologic changes in the intrafusal fibers of muscle spindles, with fiber splitting, necrosis and regeneration

Answer 18

Myotonic Dystrophy (TOPNOTCH)

Question 19

Morphology: the principal morphologic characteristic is accumulation of lipid within myocytes. The myofibrils are separated by vacuoles that stain with oil red O or Sudan black

Answer 19

Lipid Myopathies (TOPNOTCH)

Question 20

Lambert Eaton Myasthenic Syndrome is a paraneoplastic process which commonly develops in what type of carcinoma?

Answer 20

Small cell carcinoma of the lungs (TOPNOTCH)