Skeletal Muscle Pathology Flashcards
Part of muscle that envelopes single muscles
Epimysium
Part of muscle that surrounds groups of muscle fibers
Perimysium
Part of muscle that surrounds individual muscle fibers
Endomysium
Molecule involved in muscle energy metabolism, has two monomers and three types of dimers
Creatine kinase
Elevated total CK suggests this type of injury
Skeletal muscle
Molecule involved in muscle oxygen use that is released with muscle damage - also elevated with cardiac injury
Myoglobin
Molecule involved in muscle glycolysis that is released with muscle damage
Aldolase
This molecule released with muscle damage is sometimes elevated when CK is normal
Aldolase
Condition of skeletal muscle weakness due to autoantibodies against muscle acetylcholine receptor complex
Myasthenia Gravis
Myasthenia Gravis is due to autoantibodies against this
Muscle acetylcholine receptor complex
(or anti-MUSK - muscle specific kinase)
Two age peaks of Myasthenia Gravis
20’s and 60’s
Skeletal muscle condition associated with thymic tumors (Thymoma, thymic hyperplasia)
Myasthenia Gravis
Myasthenia Gravis is associated with tumors of this organ
Thymus
Who is more likely to have Myasthenia Gravis, female or male?
Female
Condition involving muscle weakness which worsens with repetition/duration
Myasthenia Gravis
Condition that commonly affects eye muscles, so patients can have ptosis and diplopia
Myasthenia Gravis
Are deep tendon reflexes preserved in Myasthenia Gravis?
Yes
ACHesterase inhibitors results in improved symptoms in this condition
Myasthenia Gravis
Condition of weakness due to antibodies against calcium channels
Lambert-Eaton Myasthenic Syndrome
Lambert-Eaton Myasthenic Syndrome is due to antibodies against this
Calcium channels
Condition where muscle strength increases with repetition/duration
Lambert-Eaton Myasthenic Syndrome
Half of Lambert-Eaton Myasthenic Syndrome cases are due to paraneoplastic syndrome, and this is the most common
Small cell carcinoma of lung
Small cell carcinoma of lung is the most often paraneoplastic syndrome that can cause this condition
Lambert-Eaton Myasthenic Syndrome
Are deep tendon reflexes preserved in Lambert-Eaton Myasthenic Syndrome?
No, are decreased
May have autonomic effects
Do ACHesterase inhibitors improve symptoms in Lambert-Eaton Myasthenic Syndrome?
No
Condition that leads to impaired acetylcholine release, because there is dysfunction in firing of presynaptic calcium channels
Lambert-Eaton Myasthenic Syndrome
Clostridium botulinum can block release of this, causing myasthenic syndrome
ACH
Does this describe neuropathic or myopathic muscle atrophy:
End result is clustering of atrophy and hypertrophy
Neuropathic
Type II fiber atrophy is associated with prolonged use of these
Corticosteroids
What is pathognomonic of muscle denervation/reinnervation?
Clusters of type I myocytes and clusters of type II myocytes
Does steroid use result in type I or type II atrophy?
Type II atrophy
Type I preservation
Acute necrosis of skeletal muscle
Rhabdomyolysis
Levels of creatine kinase and aldolase in Rhabdomyolysis
Both high due to release of cytosolic proteins
In Rhabdomyolysis, regeneration may occur via these cells
Satellite cells (muscle stem cells)
Remember that part of healing response/regeneration is central nuclei
Central nuclei in muscle indicate this process has occurred
Regeneration
In Rhabdomyolysis, this molecule may be released into the urine and damage the kidneys, causing acute renal failure
Myoglobin
Autoimmune disease with proximal muscle weakness and skin changes
Dermatomyositis
Two age groups that may have Dermatomyositis
Peds (7 years) and adults (60’s)
Dermatomyositis is an autoimmune disorder mediated by this type of cell
B cell
IgG, IgM and complement deposit in microvascular beds
Condition where IgG, IgM and complement deposit in microvascular beds, and results in microangiopathic ischemia in muscle and skin (rash, telangiectasias)
Dermatomyositis
Does Dermatomyositis affect proximal or distal muscle first?
Proximal
Condition with muscle aches and weakness with gross motor activities affected first (standing from chair, raising arms above head, climbing stairs)
Dermatomyositis
Condition with heliotrope rash on upper eyelids
Dermatomyositis
Condition with Gottron’s papules on dorsal knuckles
Dermatomyositis
Condition with characteristic skin changes including malar erythema, mechanics hands, periungual telangiectasias, and periorbital edema
Dermatomyositis
Perivascular perimysial lymphoid infiltrate is pathognomonic of this condition
Dermatomyositis
Microvascular immune complexes and perifascicular atrophy are morphologically seen in this condition
Dermatomyositis
Level of CK in Dermatomyositis
Elevated
Anti-Jo1 antibodies are against this
Histidyl tRNA synthetase
Type of antibodies seen in Dermatomyositis that target histidyl tRNA synthetase
Anti-Jo1
Anti-Mi2 antibodies target this
DNA helicase
Type of antibodies seen in Dermatomyositis that target DNA helicase
Anti-Mi2
Type of antibodies that are most common in paraneoplastic Dermatomyositis
Anti-p140
Anti-Jo1 and Anti-Mi2 antibodies are seen in this condition
Dermatomyositis
Inflammatory myopathy mediated by cytotoxic T cells
Polymyositis