Path 2 Flashcards
dermatomyositis affects? classic vs revised model
skin & muscles. humoral attack on muscle capillaries and arterioles –> MAC deposits in perivascular sites –> capillaries destroyed and muscle fibers atrophy vs overprod of IFN-inducible proteins –> high type I IFN –> endothelial cells and muscle fibers injured –> perifascicular atrophy
skin vs muscle vs constitutional sxs of DM
gottron papules, Heliotrope eruption; facial erythema; poikiloderma at Shawl/V neck/Holster sign; nailfold abnlities vs slow progressive prox muscle weakness vs interstitial lung dz, dysphagia, heart, polyarthritis/joints
DM subtypes: Clinically amyopathic DM vs juvenile DM vs malig-assoc DM
no skin sxs vs <18yo vs adenocarcinoma to cvx, lung, ovaries, pancreas, bladder, stomach; Myositis-specific ag = highly expressed in ca tissue –> immune rxns against ca cross-react w/ skel muscle fibers –> myositis
DM ab: antiMi2 vs antiJo1 vs antip155/140
against DNA helicase; exclusive in DM vs against histidyl tRNA synthetase; more common in PM vs against transcpxn factor for cellular differentiation; more common in malig associated DM
PM affects? Perforin pathway. any perifascicular atrophy of infiltrates?
skin. Perforin and granzyme granules of CD8 cells = directed towards healthy muscle fibers w/ MHC I –> necrosis. no b/c not DM
PM muscle vs constitutional sxs
Symmetrical, proximal muscle weakness in UE and LE; Facial and ocular muscles not affected vs Lung, heart, oropharynx, joints
PM subtypes: juvenile PM vs malig assoc PM
<18yo vs Colorectal, lung, hepatic ca
PM labs: ANA vs Anti Jo1 ab vs Anti-signal recognition particle (SRP) ab
nonspecific for inflamm or autoimmune vs against histidyl tRNA synthetase vs targets cytosolic protein-RNA complex that couples synthesis of nascent proteins to their proper membrane localization
how to tx PM?
glucocorticoid
Inclusion body myositis affects? Hallmark?
muscles. rimmed autophagic vacuoles containing protein aggregates like in degen dzs –> degen theory of s-IBM
proteins found in IBM
intracellular amyloid that’s immunoreactive to β-amyloid protein; phosphorylated tau, α-synuclein, ubiquitin, presenilin
IBM sxs
Asymmetrical slow progressive weakness of distal and proximal muscles
* Weak quads, finger dexterity, and grip strength
* Atrophy of quads and forearm flexors
IBM labs: high CK vs Anti-cytosolic 5’-nucleotidase (cN1A) ab
blank vs colocalize w/ granular intravacuole deposits and vacuole rims
* Exclusive in inclusion-body myositis
how to tx IBM?
glucocorticoids, wheelchair by 10yo
IBM has autoimmune pathogenesis by?
CD8 cell, B cell, anti-cN1A ab
What is immune-mediated necrotizing myopathy? any CD8 cells (PM/IBM) or perifascicular atrophy (DM) involved?
muscle fiber degeneration, necrosis, regeneration. no
IMNM skin vs muscle vs constitutional sxs
gottron, heliotrope, V sign vs prox muscle weakness vs interstitial lung dz, unknown malig risk
how to dx IMNM?
muscle bx: more necrosis, less inflamm/phag but macs can be seen around necrotic fibers
IMNM labs: High CK; Nml or high ESR, CRP vs Anti-SRP ab vs Anti-HMGCR ab
self explanatory vs triggered by VZV, HPV; targets cytosolic protein-RNA complex that couples synthesis of nascent proteins to their proper membrane localization vs Triggered by statins
how to tx IMNM?
Corticosteroids w/ methotrexate; mortality rte 2-3x higher than gen pop
metabolic myopathies
auto rec d/o leading to insufficient energy prod d/t defect of glycogen, lipid, or mito metab
Disorders of glycogen metab
mutations in genes encoding proteins for glycogen synthesis or degradation –> glycogen can accumulate in tissue
GSD Type II/Pompe dz
Mutation in GAA gene encoding acid α-glycosidase (lysosome) deficiency –> glycogen accumulates in lysosomes of skel or cardiac muscle cells –> enlarged lysosomes –> compressed cell organelles –> injure and replace muscle fibers –> dec cardiac and muscle fxn
Pompe dz clinical pres: infant onset vs late onset
1-5% of residual α-glycosidase activity; cardiomegaly, resp distress, muscle weakness, failure to thrive vs 15-40% of residual α-glycosidase activity; no cardiomegaly, resp fail d/t diaphragm, muscle weakness in limb girdle distribution (prox muscle most affected)