PMC10040642_01
Erythematous skin rash observed on the left forearm of our patient at onset (arrows). Skin rash then spread to the other extremities and trunk.
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F1
The patient also presented with generalized erythematous skin rash (Figure 1).
Muscle magnetic resonance imaging before treatment. (A,B) T2-weighted images of the right (A) and left (B) upper extremities in coronal section. (C) Short-tau inversion recovery image of lower extremities in coronal section. Arrows denote increased signal intensities of proximal muscles in bilateral upper and lower extremities.
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F2
Magnetic resonance imaging detected signal hyperintensity on T2-weighted imaging and short tau inversion recovery imaging for muscles in the proximal upper and lower extremities (Figure 2).
Histological features of right biceps brachii biopsy. (A) Hematoxylin and eosin staining shows moderate variation in fiber size, with scattered necrotic and regenerating fibers and mild lymphocytic infiltration. (B) Major histocompatibility complex class 1 immunohistochemical staining shows positivity on the sarcolemma of all fibers. (C) Sarcolemmal deposition of membrane attack complex (C5b-9) is seen in scattered fibers with C5b-9 immunohistochemical staining. (D) Fine granular expression of p62 is present in the sarcoplasm of scattered myofibers with p62 immunohistochemical staining.
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F3
Muscle biopsy showed necrosis and regeneration of muscle fibers (Figure 3). Immunohistochemistry demonstrated overexpression of major histocompatibility complex class 1 and membrane attack complex (C5b-9) on the sarcolemma and granular sarcoplasmic expression of p62 (Figure 3).
PMC10040642_02