Anti-signal Recognition Particle Antibody-positive Necrotizing Myopathy with Secondary Cardiomyopathy: The First Myocardial Biopsy- and Multimodal Imaging-proven Case

Figures

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  Figure 1.. Transthoracic echocardiography and myocardial scintigraphy. Echocardiography (A, long axis; B, four-chamber view) showed hypertrophy of the anteroseptal basal wall (18 mm, white arrow), thinning of the posterior wall (5 mm), and pericardial effusion (arrowhead). (C) 201Thallium(I) chloride (TlCl) and (D) 123I-15-4-iodophenyl-3-(R, S)-methyl-pentadecanoic acid (BMIPP) scintigraphy showed a mildly decreased uptake in the anteroseptal basal area. (E) 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy showed increased washout in the inferolateral area.

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  Figure 2.. Cardiac magnetic resonance imaging (CMRI) [cine imaging, short inversion time inversion recovery (STIR) imaging, and late gadolinium enhancement (LGE) imaging] and 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) performed on admission (A) and at one year after admission (B). On admission, cine imaging showed pericardial effusion, and STIR imaging detected a high-intensity region in the inferolateral wall (red arrowheads). LGE imaging revealed late transmural gadolinium enhancement of the inferolateral wall (white arrowheads). 18F-FDG-PET showed an abnormal uptake in the anteroseptal wall of the left ventricle (arrow). These findings had improved at one year after admission, but the late gadolinium enhancement persisted [cine, repetition time (TR) 2.44 ms, echo time (TE) 1.2 ms; STIR (T2-weighted), TR 2,400 ms, TE 60 ms; LGE, TR 4.03 ms, TE 1.2 ms].

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  Figure 3.. Histopathological findings of the left biceps brachii muscle. Hematoxylin and Eosin staining showed moderate variations in fiber size and many necrotic fibers (A), positive major histocompatibility complex (MHC) class I (B), and membrane attack complex (MAC) (C) immunostaining.

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  Figure 4.. Histopathological findings of the septal wall obtained during the right ventricle biopsy examination. Hematoxylin and Eosin staining showed interstitial fibrosis (A), binucleated myocytes, hypertrophic myocytes, and variations in the sizes of the myocyte nuclei (B). Immunostaining showed the infiltration of CD68-positive macrophages (C) and CD8-positive lymphocytes (D). Electron microscopy revealed myofibril disarrangement and the proliferation of mitochondria in the myocytes (E).

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  Figure 5.. Clinical course of this case. CK: creatine kinase, IVIG: intravenous immunoglobulin, mPSL: methylprednisolone, PSL: prednisolone