Peripheral Nervous System and Skeletal Muscle

Question 1

immunologically mediated demyelinating peripheral neuropathy that may lead to life-threatening respiratory paralysis

T cell mediated hypersensitivity with antibody component against peripheral nerves –> demyelination

ASSOCIATIONS:
Campylobacter jejuni
CMV
Epstein-Barr virus
Mycoplasma pneumoniae
prior vaccination

Answer 1

Guillain-Barré Syndrome (Acute Inflammatory
Demyelinating Polyneuropathy)

CSF: ALBUMINOCYTOLOGIC DISSOCIATION - increased protein, little pleocytosis

Question 2

MC chronic ACQUIRED peripheral neuropathy

Answer 2

Chronic Inflammatory Demyelinating Poly (radiculo) neuropathy (CIDP)

Question 3

MCC of peripheral neuropathy

Answer 3

DM

Question 4

MC inherited peripheral neuropathy

Answer 4

CHARCOT MARIE TOOTH DISEASE

Question 5

Autoimmune disease that is usually associated with autoantibodies directed against ACh receptors

POSTSYNAPTIC ACh RECEPTOR

strong association between pathogenic anti–ACh receptor autoantibodies and thymic abnormalities

fluctuating weakness that worsens with exertion and often over the course of the day

Answer 5

Myasthenia gravis

ASSOCIATIONS:

THYMOMA
THYMIC HYPERPLASIA

EOM - diplopia, ptosis

Question 6

autoimmune disorder caused by antibodies that block ACh release by
inhibiting a presynaptic calcium channel

PRESYNAPTIC ACh RECEPTOR

presents with weakness in the extremities that improves with repetitive stimulation

often a paraneoplastic disorder associated with lung cancer

Answer 6

Lambert-Eaton myasthenic syndrome

ASSOCIATIONS:

NEUROENDOCRINE CA of the LUNGS

extremities

Question 7

immunologic disease in which damage to small blood vessels contributes to muscle injury

vasculopathic changes can be seen as telangiectasias
(dilated capillary loops) in the nail folds, eyelids, and gums
and as dropout of capillary vessels in skeletal muscle

typically affects the proximal muscles first – tasks such as getting up from a chair and climbing steps become increasingly difficult

fine movements controlled by distal muscles are affected only
late in the disease

Answer 7

Dermatomyositis

HELIOTROPE RASH
GOTTRON PAPULES

perifascicular atrophy

Question 8

adult-onset inflammatory myopathy that shares myalgia and weakness with dermatomyositis but lacks its distinctive cutaneous features

Answer 8

Polymyositis

Question 9

MC complication of statins (e.g., atorvastatin, simvastatin, pravastatin).

Answer 9

Myopathy

Question 10

The MC muscular dystrophies

X-linked and stem from mutations that disrupt the function of a large
structural protein called DYSTROPHIN

caused by loss-of-function mutations in the dystrophin gene on the
X chromosome

Answer 10

X-Linked Muscular Dystrophy With Dystrophin Mutation
Duchenne Muscular Dystrophy
Becker Muscular Dystrophy

Immunohistochemical studies for dystrophin:

Duchenne muscular dystrophy - ABSENCE of the normal sarcolemmal staining pattern

Becker muscular dystrophy - REDUCED staining

Question 11

benign tumors that exhibit Schwann cell differentiation and often arise directly from peripheral nerves

component of NF2

ENCAPSULATED

S-100

Answer 11

SCHWANNOMAS

MUTATION - NF2 (Merlin) Ch 22

comprised of an admixture of:
dense - Antoni A
loose - Antoni B

central “nuclear-free zones” ramified by palisading nuclei - VEROCAY BODIES

Question 12

Benign nerve sheath tumors that are more heterogeneous in composition than schwannomas.

neoplastic Schwann cells are admixed with perineuriallike cells, fibroblasts, mast cells, and CD34+ spindle cells

Answer 12

NEUROFIBROMA

MUTATION - NF1 CH17

BAG OF WORMS
“SHREDDED CARROT APPEARANCE”

Question 13

Sarcoma arising in an anatomic compartment of a major nerve or preexisting nerve sheath tumor or in an NF1-patient

Answer 13

Malignant Peripheral Nerve Sheath Tumors

MALIGNANT TRITON TUMOR - (+) rhabdomyoblastic proliferation