Autoimmune Msk Problems Flashcards
What is the lab work of non-infectious inflammatory myopathies
Positive ANA
Anti-Jo-1 AB
Anti-Mi-2 AB’s
Increased creatinine and aldolase
Give two examples of non-infectious inflammatory myopathies. What are they?
Don’t matter myositis + polymyositis
Immune-mediated disorders with symmetrical muscle involvement and involvement of other organs
What does muscle biopsy show for polymyositis
Necrotic and regenerating muscle with the lymphocytic and macrophage infiltrate
atrophy not prominent
What does muscle biopsies show for dermatomyositis
Inflammatory reaction i.e. lymphocytic
Atrophy of muscle fibres = prominent
Capillary damage + muscle – >ischaemia + atrophy
If a patient presents with the matter my situs what else do you need to consider the possibility of?
Gastric carcinoma
What is the aetiology of dermatomyositis
CD4 cells target capillaries + skeletal muscle
Antibodies + complement damage capillaries
What are the clinical features of the dermato myositis
Rash + upper eyelid = purple = heliotrope/raccoons
Malar rash
Red GOTTRON papules + elbows knuckles knees
Hallmark bilateral proximal muscle weakness – Can’t come hair due to weak shoulders
Morning stiffness fatigue + dysphagia @ upper oesophagus
Inside the muscle fascicle where exactly does the information occur in dermatomyositis?
Inflammation of the perimysium ->
perifascicular atrophy
In polymyositis is their proximal or distal muscle weakness?
Is the skin involved?
Where is inflammation occurring?
What immune cell is hallmark?
Proximal muscle weakness
Skin not involved
Inflammation @endomysium with necrotic muscle fibres
CD8+
What are antibodies directed against in polymyositis?
Transfer RNA synthetases
Nuclear + cytoplasmic antigens @ skeletal muscle
What initiates the CD8 positive cells?
HIV,
HTLV – 1,
coxsackie B
Alter MHC 1 MHC 2 antigens
Give the two types of X-linked muscular dystrophies
Duchenne muscular dystrophy
Becker muscular dystrophy
What is Duchenne muscular dystrophy the characterised by
Muscle wasting: skeletal muscle –> adipose tissue
Explain the genetics of Duchenne muscular dystrophy
X-linked
Frameshift mutation –Deletion of dystrophin gene – >
cannot anchor muscle fibres in skeletal + cardiac muscle– >
Can’t connect intracellular muscle cytoskeleton (actin)
to
transmembrane proteins alpha + beta dystroglycan. Which are connected to the extracellular matrix
What does the truncated dystrophin protein lead to
Inhibited muscle regeneration
Where does the muscle weakness begin from?
@ what age?
where does it progressed to?
Proximal muscle weakness @ 1 year old – >progress to distal muscle
E.g. begins in pelvic girdle muscle – >progress superiorly
Explain the Hallmark issue related to the leg in Duchenne muscular dystrophy
Pseudohypertrophy of the calf
Learn to walk + Proximal muscle starts to we can – >child puts more force on calf muscle to walk – >hypertrophy
Overtime disease progresses – >
Muscle weakens as disease moves distally and affects calf – >convert calf muscle to fat– > calf looks big but is full of fat
What does the damaged muscle cell release into the Serum?
Creatinine kinase + aldolase
Why does the child normally die from Duchenne muscular dystrophy?
Cardiac/respiratory (diaphragm) failure