Neuropathology Peripheral Flashcards
What connective tissue component is a multilayered concentric connective tissue sheath that groups subsets of axons into fascicles?
Perineurium
The inflammation seen in GBS is located in what 2 microstructures?
Perivenular and Endoneurial
Besides axonal neuropathy and demyelination what else can be seen in the histopathology of DM neuropathy?
Endoneurial arterioles show thickening, hyalinanization and intense PAS positivity of their walls and extensive reduplication of the basement membrane
Anti CV2 antibodies lead to what type of peripheral nerve damage?
Mixed axonal and demyelinating sensorimotor neuropathy
What are the components of the POEMS syndrome?
Polyneuropathy Organomegaly Endocrinopathy Monoclonal gammopathy Skin changes
Identify which CMT/genetic neuropathy results with alteration to the function of the ff:
- Myelin protein zero
- Duplication of a region in chromosome 17 that includes myelin protein 22 (PMP 22)
- GJB1 which encodes conenexin 32
- MFN2 gene required for mitochondrial fusion
- Deletion of the gene encoding PMP22
- Transthyretin gene and protein
- alpha galactosidase
- beta galactosidase
- Myelin protein zero CMT1B
- Duplication of a region in chromosome 17 that includes myelin protein 22 (PMP 22) CMT1A
- GJB1 which encodes conenexin 32 CMT1x
- MFN2 gene required for mitochondrial fusion CMT2a
- Deletion of the gene encoding PMP22 Hereditary neuropathy with pressure palsy
- Transthyretin gene and protein Familial amyloid polyneuropathies
- alpha galactosidase: Fabry disease
- beta galactosidase: Krabbe disease
Tomaculi, or bulbous myelin sheaths at the end of internodes are found in?
HNPP
What percentage of MG patients will have a thymoma?
How about thymic hyperplasia?
10%
30%
What structure is inhibited in Lambert Eaton Myasthenic syndrome?
Presynaptic calcium channel
What is the difference in the MOA of botox and curare in inducing weakness?
Botox: Blocks release of Ach
Curare: Blocks the Ach receptor
What pattern of muscle fiber damage is seen
- Dermatomyositis
- Corticosteroid use
- Disuse
- Dermatomyositis: Perifascicular atrophy
- Corticosteroid use: Type 2 fiber atrophy with sparing of type 1
- Disuse: Type 2 fiber atrophy with sparing of type 1
Identify if type 1 or 2 muscle fiber:
- Fast movement
- Aerobic exercise
- Lipid content
- Glycogen content
- High oxidative capacity
- High mitochondrial density
- Pale red/ tan color
- Fast movement 2
- Aerobic exercise 1
- Lipid content 1
- High Glycogen content 2
- High oxidative capacity 1
- High mitochondrial density 1
- Pale red/ tan color 2
Group atrophy is a typical finding in what etiology of muscle damage?
When type grouping is seen what process is likely occurring/occurred?
Disrupted innervation
Reinnervation
What vasculopathic changes are prominent in Dermatomyositis?
- The 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. - Biopsies of muscle and skin may show deposition of the complement membrane attack complex (C5b-9) within capillary beds in both tissues.
What clinical characteristics are associated with the ff autoantibodies in dermatomyositis?
• Anti-Mi2 antibodies
• Anti-Jo1 antibodies
• Anti-P155/P140
Anti-Mi2 antibodies (directed against a helicase implicated
in nucleosome remodeling) show a strong association
with prominent Gottron papules and heliotrope
rash (described later).
Anti-Jo1 antibodies (directed against the enzyme histidyl
t-RNA synthetase) are associated with interstitial lung
disease, nonerosive arthritis, and a skin rash described
as “mechanic’s hands.”
Anti-P155/P140 antibodies (directed against several transcriptional
regulators) are associated with paraneoplastic
and juvenile cases of dermatomyositis.
What is the classic histopathologic finding in dermatomyositis will differentiate it from PM?
Perifascicular atrophy
Perimysial connective tissue contains mononuclear cells
In PM: Mononuclear inflammatory cell infiltrates in endomysial CT. Sometimes myofibers with otherwise normal morphology
appear to be invaded by mononuclear inflammatory cells. Degenerating necrotic, regenerating, and atrophic myofibers
are typically found in a random or patchy distribution.
What proportion of patietns with dermatomyositis also have:
- Interstitial lung disease
- Dysphagia
- Associated malignancy
- Interstitial lung disease 10%
- Dysphagia 1/3
- 15-24% in adults
Whereas CD4+ T helper cells and deposition of C59b in capillary vessels is involved in DM what cells are seen in PM and IBM?
Cytotoxic T cells– endomysial location
What is the most common inflammatory myopathy in patients older than 50 years old?
Inclusion body myositis
Rimmed vacuoles are found in what inflammatory myopathy? What do they contain?
IBM
beta amyloid, TDP 43, ubiquitin
What are the main cellular elements that dystrophin links?
Cytoskeletal proteins linked to:
++ Transmembrane proteins: dystroglycan, sarcoglycan that are linked to ECM laminin
++ Dystrobrevin and syntrophins that are linked to caveolin
What diseases result with mutations in the following proteins:
- Caveolin and sarcoglycan proteins
- Alpha 2 laminin (merosin)
- Dystrophin
- Caveolin and sarcoglycan proteins: LGMD
- Alpha 2 laminin (merosin): Autosomal recessive congenital muscular atrophy
- Dystrophin: Duchenne and Becker
Which congenital myopathy presenting as floppy infant is consistent with the ff findings:
1. Cytoplasmic cores represent
demarcated central zones in
which the normal arrangement of sarcomeres is disrupted and mitochondria are decreased in number– Gene and locus involved is the Ryanodine Receptor-1 RYR1
2. Aggregates of spindle-shaped particles (nemaline rods); occur predominantly in type 1 fibers; derived from Z-band material (α-actinin) and best seen on modified Gomori stain or by electron microscopy AD NEM1—α-tropomyosin 3 (TPM3) gene;
1q22–q23
- Central core disease
2. Nemaline myopathy
What are the 2 histopathologic findings in Duchenne muscular dystrophy?
- Segmental myofiber degeneration and regeneration associated with an admixture of atrophic myofibers. As the disease progresses fatty replacement, extensive variation in fiber size and endomysial fibrosis.
- Complete absence of membrane associated dystrophin upon staining
What are the 5 key features of myotonic dystrophy?
- Myotonia
- Weakness
- Cataracts
- Endocrinopathy
- Cardiomyopathy
What is the triad of emery dreifuss muscular dystrophy?
Humeroperoneal weakness
Early contracures of the Achilles, spine and elbows
Cardiomyopathy with conduction defects
DUX4 gene overexpression results in what muscular dystrophy?
Fascioscapulohumeral dystrophy
What enzyme is missing in Pompe disease?
How about McArdle?
Acid maltase: deficiency results in impaired lysosomal conversion
of glycogen to glucose
Myophosphorylase deficiency: One of the
more common glycogen storage diseases affecting skeletal muscle; it also results in episodic muscle damage with exercise
Involvement of what muscle group sets mitochondrial myopathies apart?
EOMs– have the MOST mitochondria per mass of any of the body’s muscles
Remember chronic progressive external ophthalmoplegia
All mitochondrial DNA with inherited from?
Mom
What are the 3 components of the Kearns Sayre syndrome?
- Ophthalmoplegia
- Pigementary degeneration of the retina
- Complete heart block
Mutations in the ff genes lead to which disease:
- RYR1
- SCN4A
- CACNA1S or DHP receptor
- CLCN1
- RYR1: Central core myopathy and malignant hyperthermia (calcium channel)
- SCN4A: Paramyotonia congenita and hyperkalemic periodic paralysis– Sodium channel
- CACNA1S or DHP receptor: Hypokalemic paralysis– calcium channel
- CLCN1: Myotonia congenita/ generalized myotonia (Becker)– Chloride channel
Antoni A (Dense) Antoni B (Loose) are findings in which tumor?
Schwannoma
Which type of neurofibroma is associated with nerve roots or larege nerves and are UNIFORMLY NF1 ASSOCIATED?
- Superficial cutaneous neurofibromas often present as pedunculated nodules that can be seen isolated (if sporadic) or multiple (if NF1-associated).
- Diffuse neurofibromas often present as a large plaquelike elevation of skin and are typically NF1-associated.
- PLEXIFORM NEUROFIBROMA can be found in deep or superficial locations in association with nerve roots or large nerves and are uniformly NF1-associated.
What tumor suppressor is missing in schwann cells of NF1 neurofibroma?
Neurfibromin
What perecentage of NF1 patients will have Malignant peripheral nerve sheath tumor converting from plexiform neurofibroma?
5-10%
A MPNST with a rhabdomyoblastic differentiation is called a?
Triton tumor
What genes are the NF syndromes seen?
1: 17q11.2
2: 22q12