MSK path III Flashcards
polymyositis
adult onset inflammatory myopathy that shares myalgia and weakness with dermatomyositis but lacks cutaneous features
mononuclear inflammatory cells in endomysial location
polymyositis
CD68
macrophages
inclusion body myositis
late adulthood >50 years old
most common inflammatory myopathy in adults >65 y.o
inclusion body myositis
presentation inclusion body myositis
slowly progressive muscle weakness that tends to be most severe in quads and distal Upper extremity muscles
trichrome stain
nuclei in center of muscle cells and myofibers have rimmed vacuoles
polymyositis
Main Tx for inflammatory myopathies
corticosteroids
steroid R disease of inflammatory myopathies
Tx?
azathioprine, MTX, IV Ig, cyclophosphamide, cyclosprine, rituximab
will Tx work for inclusion body myositis
responds poorly
most common complication statins
myopathy
thyrotoxic myopathy
acute or chronic proximal muscle weakness, precedes other Sx hyperthyroidism
Bindge drinking can cause what myopathies
rhabdomyolysis, myoglobinuria and renal failure
what type of atrophy does alcohol cause in muscle
type II atrophy
chromosome 19q13.1 assoc with what gene
inheritance
RYR1- autosomal dominant
clinical findings of mutation in RYR 1
floppy infant
scoliosis, hip dislocation, foot deformities,
malignant hyperthermia!!!
muscle cells show cytoplasmic cores with central zones of abnormal sarcomeres and decreased mitochondria thorughout
RYR1 mutation
“central core disease”
What is NEM
nemaline myopathy
presentaiton NEM
weakness, hypotonia
floppy infant
histo NEM
spindle shaped particles in type I fibers
gomori stain is best
clinical findings centronuclear myopathy
floppy infant
poor prognosis in X linked form
weakness and hypotonia
histo centronuclear myopathy
nuclei in center of myofiber especially type I
mutation in centronuclear myopathy
XL- myotubularin gene MTM1
CNM2 gene
progressive muscle damage that manifests between childhood and adulthood
muscular dystrophies
most common muscular dystrophies have what inheritance and what is dysfucntional
X linked
mutation in dystrophin
syndromes from loss of function in dystrophin gene on X chromosome
duchenne and becker
when are duchenne and becker usually Dx
around a year because slow at walking
what does dystrophin do
linkts actin to syntrophins
raltionship between cell membranes and proteins
Bx in young boy mm show segmental myofiber degeneration and regeneration with atrophic myofibers
no inflammation
some fat infiltration
beckers or duchenne
absent normal sarcolemmal staining on immunohistochem
duchenne
reduced sarcolemmal staining on immunohistochem
becker
what is pseudohypertorphy
when because losing some muscle fibers the others try to compensate and grow big. look like have big muscles, but lots is fat
which muscular dystrophy still has some dystrophin
becker
sequelae of muscular dystrophy
joint contractures, scoliosis, worsening respiratory reserve, sleep hypoventilation
serum CK MM in dystrophy
elevated in first decade
then falls as disease progresses
what confirms muscular dystrophy
genetic studies
inheritance of myotonic dystrophy
auto dominant
myotonic dystrophy is associated with what other system disorders
skel mm weakness, cataracts, endocrinopathy and cardiomyopathy
what is myotonia
sustained involuntary contraction of muscles
what causes myotonic dystrophy
expansions CTG triplet repeats at 3’ noncoding region of myotonic dystrophy protein kinase
what muscular dystrophy has mutations that encode nuclear lamina proteins
emery dreifuss muscular dystrophy
presentation of decrease in lipid or glycogen metabolism
msucle cramping and pain when exercise or fasting
or
slow progressive muscle damage without episodic manifestations
What is McArdles disease
cannot breakdown sugars
ragged red fibers
mitochondrial deficiency
phonogrpah record appearance of mitochonria
mitochondrial abnormality
myopathies from mitochondrial problems
elevated CK
rhabdomyolysis
weakness
what is spinal muscular atrophy
loss of motor neurons which leads to muscle weakness and atrophy
presentation spinal muscular atrophy
floppy infant
Sx of ion channel myopathy
elevated, depressed or normal serum K levels
“hyperkalmic, hypokalemic and normokalemic periodic paralysis”
malignant hyperthermia
hypermetabolic state: tachycardia, tachypnea, muscle spasms and hyperpyrexia
most common trigger for malignant hyperthermia
halogenated inhalaltional agents and succinylcholine
CD cells involved in polymyositis
CD8
