Table 1.

Histological description of individual patient biopsies.

Diagnosis	Clinical information	Biopsy Findings
Jo-1	Muscle pain and weakness	Occasional mildly or moderately atrophic fibres.
Jo-1	Muscle pain, weakness and shortness of breath	Atrophic fibres and endomysial inflammatory cells with surface expression of beta 2 microglobulin on muscle fibres and complement terminal attack complex.
Jo-1	Muscle pain and weakness	Scattered moth-eaten fibres, myofibrillar disarray with increased variation in fibre size and endomysial cell debris.
Jo-1	Proximal upper and lower limb muscle pain with elevated creatinine kinase	Necrotic and regenerating fibres with atrophic fibres, split fibres and fibres with central nuclei. Endomysial inflammatory infiltrate.
Jo-1	Progressive bilateral leg swelling with elevated creatinine kinase and inflammatory markers.	Necrotising inflammatory myositis with inflammatory cell infiltration and enlarged central vacuoles.
IBM	Trunk, upper and lower limb weakness.	Inflammation, degenerative and regenerating fibres, multiple rimmed vacuoles; with inclusions
IBM	Upper and lower limb weakness and wasting with difficulty swallowing.	Atrophic fibres and fibres containing rimmed vacuoles, and inflammatory cell infiltrate.
IBM	Upper limb muscle pain and tenderness and elevated creatinine kinase.	Inflammatory changes and infiltrate with fibre atrophy, degeneration, regeneration, adipose tissue replacement and myofibrillar disorganization. Increase in endomysial collagen.
IBM	Pain and weakness in proximal lower limb	Atrophic, necrotic and regenerating fibres with adipose tissue replacement. Focal fibrosis, endomysial inflammation, internal nuclei and lymphocytic. Rimmed vacuoles with up-regulation of beta 2 microglobulin.
IBM	Muscle pain and weakness	Hypertrophic and atrophic fibres embedded in fibrotic stroma. Necrotic fibres engulfed by macrophages and endomysial lymphocytic infiltration. Rimmed vacuoles and ragged red fibres and inclusions in myofibres.