Figure 3.

Representative staining of standard stained sections of jIIM from patients with DM (P4), anti-Jo1-ASyS (P14), OM (P3), and control. In H&E-stained sections, perifascicular atrophy (black arrows) is prominent in biopsies from patients with DM and anti-Jo1-ASyS. In OM, atrophic fibers are distributed throughout the section. Inflammatory cell infiltrates (white arrows) are mainly located perifascicularly in DM, perifascicularly in anti-Jo1-ASyS, and perimysial in OM sections. In Gömori trichrome, muscle fibers show a strong alteration of myofibrillar structures in DM and anti-Jo1-ASyS (arrows) but not in OM. ALP is highly upregulated (black) in the perimysium of anti-Jo1-ASyS and shows some subtle upregulation in DM but not in OM. COX-negative fibers appear blue in the COX–SDH staining with an exclusively high number of COX-deficient fibers in the DM sections (magnification 20×). (DM = dermatomyositis; ASyS = antisynthetase syndrome; OM = overlap myositis).