Fig. 2

HIV-associated IBM. Pathomorphological characteristics of IBM associated with HIV as seen on muscle biopsy. (a) Myopathic picture with pronounced fiber size variation with hypotrophic and hypertrophic fibers and endomysial lymphocytic infiltrates. No overt rimmed vacuoles are seen. Gömöri trichrome staining (× 200). (b) In other ares of the same biopsy specimen, a milder myopathic picture is evident with only single lymphomonocytic cells in the endomysium. No overt rimmed vacuoles are seen. Gömöri trichrome staining (× 200). (c) Presence of COX-negative and SDH-positive myofibers. COX-SDH staining (× 200). (d) Myofibers display varying sarcolemmal (and sarcoplasmic) positivity for MCH class I. MHC class I staining (× 200). (e) Myofibers display varying sarcolemmal (and sarcoplasmic) positivity for MHC class II. MHC class II staining (× 200). (f) Single small fibres with initial coarse p62⁺ autophagic material mostly localized subsarcolemmaly and in perinuclear areas (× 600). COX  cytochrome oxidase immunohistochemistry; HIV  human immunodeficiency virus; IBM  inclusion body myositis; MHC  major histocompatibility complex; SDH  succinate dehydrogenase