Fig. 3

Histopathological findings. (A) Skin pathology in P12 showed sclerosis of the reticular dermis with excessive collagen deposition and scarce lymphocyte infiltration, but the papillary dermis and the epidermis were not affected (HE staining). (B) Scattered regenerative myofibers in P10 (HE staining, arrows). (C) Perivasculitis (arrow) and transmural vasculitis with an occluded lumen (arrowhead) in skeletal muscle of P4 (HE staining). (D) Prominent fascial and perivascular T lymphocytes infiltration in P4 (CD3 staining, arrows). (E) Eosinophils scattered in the fascia (E, HE staining), extending to the adjacent endomysium in P2 (F, HE staining). (F) Typical perifascicular atrophy adjacent to the inflammatory perimysium in P3 (arrows, HE staining). (G) MAC deposition on the sarcolemma of nonnecrotic myofibers and the intramuscular capillaries which were underlying the fascia in P3. (H) Vascular endothelial cells in the fascia and perifascicular endomysium was preserved in P3 (CD31 staining). (I-L) Perifascicular MHC-I (J) and MHC-II (K) expression but without perifascicular atrophy (I, HE staining) and MxA staining (L). MAC = membrane attack complex; MHC = major histocompatibility complex class; MxA = myxovirus resistance protein