Internal Medicine

0521779407-17 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:57

Polymyositis and Related Disorders 1191

■DM: CD4+lymphocytes in perimyseal & perivascular distribution,

perifascicular atrophy

■IBM-like PM w/ rimmed vacuoles in fibers & inclusions on electron

microscopy

■Autoantibodies (useful for prognosis)

➣Nonspecific ANA in 15–30%

➣Myositis specific autoantibodies

Anti-synthetase (eg, anti-Jo-1)

More common in PM than DM

Interstitial lung disease

Arthritis

Raynaud’s

Fever

Mechanic’s hands

Fair treatment response

Anti-Signal Recognition Peptide (SRP)

PM

Sudden onset

Cardiomyopathy

Poor prognosis

Anti-Mi-2

DM

Very good prognosis

differential diagnosis

■Myasthenia gravis, muscular dystrophies

■Thyroid disease (hyper, hypo), adrenal disease (hyper, hypo), hyper-

parathyroism, aldosteronism, carcinoid

■Abnormal Na, K, Ca, P, Mg

■Trichinosis, viruses (influenza, Coxsackie, HIV)

■Eaton-Lambert, paraneoplastic neuromyopathy

■Alcohol, beta-blockers, cholesterol-lowering agents

➣Clozapine, cocaine, colchicine, cylcosporine, hydroxycholo-

quine, glucocorticosteroids, penicillamine

■Glycogen storage disease, carnitine deficiency, mitochondrial myo-

pathy

■Sarcoid, amyloidosis, sarcopenia of aging, hysteria

management

What to Do First

■Assess baseline strength objectively: grade specific muscle groups

on 1 to 5 scale

■Check baseline CK & other muscle enzymes