Pathology Muscle and Soft Tissue Flashcards
What is dermatomyositis? What is it associated with? How do we treat it?
Inflammatory disorder of skin & skeletal muscle
Unknown etiology, sometimes associated with carcinoma
Treatment: corticosteroids
What are the clinical features of dermatomyositis?
Bilateral proximal muscle weakness (distal later)
3 key skin changes: rash of upper eyelids (heliotrope), malar rash, red papules on elbows, knuckles & knees (Grotton lesions)
What lab findings are associated with dermatomyositis?
Lab findings
Increased creatine kinase
Positive ANA and Anti-Jo-1
Perimysial (OUTER layer) inflammation (CD4+ T cells) w/perifascicular atrophy on biopsy
What is polymyositis? What cellular features do we see and how is it different from dermatomyositis?
Inflammatory disorder of skeletal muscle
Resembles dermatomyositis, but skin is not involved
Endomysial inflammation (CD8+ T cells) w/necrotic fibers
What are X-linked muscular dystrophys and what type of mutations cause it?
Degenerative disorder characterized by muscle wasting & replacement of skeletal muscle by adipose
Due to mutations of dystrophin which anchors cytoskeleton to ECM
Mutations often spontaneous due to large gene size
What is Duchenne’s? How does it present, what lab values are associated with it and what is the prognosis?
Duchenne’s – deletion of dystrophin
Proximal muscle weakness at 1 year old
Calf pseudohypertrophy
Serum CK elevated
Death from respiratory failure
What is Becker’s? Compare it to Duchenne’s.
Becker’s – mutated dystrophin, milder
What happens with Myasthenia Gravis and how does it present?
Autoantibodies against nAch receptor at NMJ
Muscle weakness worsens w/use & improves w/rest
Classically involves eyes → ptosis, diplopia
What is Myasthenia Gravis often associated with?
Thymic Hyperplasia or Thyoma
How do we confirm a diagnosis of Myasthenia Gravis and what treatment options are there?
Tx: anticholinesterase inhibitors (stigmines long-term)
Dx with edrophonium - an effective acetylcholinesterase inhibitor that will reduce the muscle weakness by blocking the enzymatic effect of acetylcholinesterase enzymes
Interestingly in Lambert Eaton, it does not have as great of an effect since the problem is that you’re not releasing enough acetylcholine
What is Lambert Eaton Syndrome and how does it present? What condition is associated with this and how do we treat it?
Autoantibodies against presynaptic Ca channels at NMJ
causing impaired Ach release
Paraneoplastic syndrome
Clinical: proximal weakness, improves with use (spares eyes)
Resolves with resection of cancer (not anticholinesterase)
What is a lipoma?
Benign tumor of adipose
Most common benign soft tissue tumor in adults
What is a liposarcoma?
Malignant tumor of adipose
Most common malignant soft tissue tumor in adults
Lipoblast is characteristic cell
What is rhabdomyoma and what condition is associated with it?
Benign tumor of skeletal muscle
Cardiac rhabdomyoma is associated with tuberous sclerosis
What is rhabdomyosarcoma andhow do we test for it? Where is it most common?
Malignant tumor of skeletal muscle
Most common malignant soft tissue tumor in children
Rhabdomyoblast is characteristic cell, desmin positive
Most common site is head, neck, vagina is classic site in young girls
