46 下列有關polymyositis的敘述，那一項較不可能？

 須考慮connective tissue disease的可能性

須考慮carcinoma的可能性

大多數病人有proximal muscle weakness

大多數病人在proximal limbs會麻木（numbness）

ans d

sensory problem is not involved!!!!!

dermatomyositis and polymyositis = association with carcinoma

Polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM) are the major members of a group of skeletal muscle diseases called the idiopathic inflammatory myopathies

In both polymyositis and dermatomyositis, immune-mediated muscle inflammation and vascular damage occur. In polymyositis, the immune system is primed to act against previously unrecognized muscle antigens. This is a T-cell – mediated autoimmune process. In dermatomyositis, complement-mediated damage to endomysial vessels and microvasculature of the dermis occurs.

Idiopathic inflammatory myopathies: clinical features

Clinical Features	Dermatomyositis	Polymyositis	Inclusion Body Myositis
Age at onset	Children/adults	Adults (> 18 years)	Adults (> 80 years)
Sex	F = M	F > M	M > F
Ethnic group	All	All, HLA restriction according to race	Whites > blacks, ethnic clusters
Familial association	No	No	Yes
Other disorders	Neoplasm, CTD, autoimm. dis.	Autoimm. dis., viral infections	CTD, viral infections
Main clinical manifestations	Cutaneous* and muscle weakness: symmetrical prox. legs > arms neck flexors > neck extensors, myalgia	Muscle weakness: symmetrical prox. legs > arms neck flexors > neck extensors	Muscle weakness: symmetrical prox. legs > arms asymmetric prox./distal leg and arm muscle, wrist/fingers flexors ≥ deltoids
EMG	Myopathic	Myopathic	Myopathic or neurogenic
Muscle enzymes	High or normal	High	Normal or high
Muscle biopsy	Perifascicular atrophy infiltrates, capillary alterations non-necrotic muscle fibers	Endomysial inflammatory cell infiltrates surrounding and invading	Endomysial inflammatory cell infiltrates surrounding and invading non-necrotic muscle fibers, vacuolated m. fibers
Response to immunosuppression	Yes	Yes	No