ICD-11 classes
08 Diseases of the nervous system
Diseases of neuromuscular junction or muscle
Primary disorders of muscles
4A41 — Idiopathic inflammatory myopathy
4A41.2 — Inclusion body myopathy
4A41.20 — Inflammatory inclusion body myositis

ICD-11 4A41.20 — Inflammatory inclusion body myositis

Inclusion body miositis (IBM) is the most common idiopathic inflammatory myopathies after age 50. It typically presents with chronic insidious proximal leg and/or distal arm asymmetric muscle weakness leading to recurrent falls and loss of dexterity. Creatine kinase is up to 15 times elevated in IBM and needle electromyography mostly shows a chronic irritative myopathy. Muscle histopathology demonstrates endomysial inflammatory exudates surrounding and invading non-necrotic muscle fibres often times accompanied by rimmed vacuoles and protein deposits. Despite inflammatory muscle pathology, it likely that IBM is has a prominent degenerative component as supported by refractoriness to immunosuppressive therapy.

The diagnosis includes nothing.

It has no clarifying diagnoses.

The diagnosis is coded elsewhere:

• Inclusion body myopathy #3641
• Inclusion body myopathy #10083
• Inclusion body myopathy #18369