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Table 3 Myopathologic markers of muscle biopsy slides

From: Scleroderma-polymyositis overlap syndrome versus idiopathic polymyositis and systemic sclerosis: a descriptive study on clinical features and myopathology

Characteristics Number SSc-overlap (n = 24) Number PM (n = 24) Significance (P value)
Necrotic muscle fibers 24 23 (96%) 24 16 (67%) 0.023b†
Lymphocytic infiltrates 24 15 (63%) 24 13 (54%) NS
Positive MHC class I staining 12 11 (92%) 18 12 (67%) NS
Inflammationa 24 19 (79%) 24 18 (75%) NS
MAC staining 10 5 (50%) 13 5 (39%) NS
Fibrosis 19 5 (26%) 24 2 (8%) NS
Presence of COX-negative fibers 10 3 (30%) 10 6 (60%) NS
  1. MAC, Membrane attack complex; NA, not applicable; NS, not significant.
  2. aInflammation is defined as positive MHC class I staining or/and presence of lymphocytic infiltrates.
  3. bStatistically significant.