Inflammatory Myopathy Associated with Anti-mitochondrial Antibody-negative Primary Biliary Cholangitis Diagnosed by a Liver Biopsy

Abstract

Anti-mitochondrial antibody (AMA)-associated myopathies represent a homogeneous disease entity with severe arrhythmia and slowly progressive proximal muscle weakness with lordotic posture, irrespective of the presence of primary biliary cholangitis (PBC). We herein report a case of myositis associated with PBC without AMAs. A 48-year-old woman presented with clinical features very similar to AMA-associated myositis, despite negative AMAs. PBC, ascertained by a liver biopsy performed based on mildly elevated liver enzymes, and the efficacy of steroid therapy on muscle weakness confirmed the diagnosis of immune-mediated myositis. When AMAs are negative, a liver biopsy is indispensable for diagnosing treatable PBC-associated myositis.

Update on autoantibodies and related biomarkers in autoimmune inflammatory myopathies

“…may add important light to the pathophysiology and diagnosis of AIM. AMAassociated myopathies are reported as a homogeneous disease entity with severe arrhythmia and slowly progressive proximal muscle weakness with lordotic posture, features which are irrespective of the presence of primary biliary cholangitis (PBC) [129]. Albayda et al reported a small cohort of seven AIM (DM and PM) with conventional AMA (M2 EP, MIT3) detected by ELISA [128].…”

“…There is considerable interest in the malfunction of mitochondria in AIM and other rheumatic diseases [ 134 ▪ , 135 ] suggesting that the presence of antimitochondrial antibodies (AMA) found in up to 10% of AIM [ 130 ▪▪ ] may add important light to the pathophysiology and diagnosis of AIM. AMA-associated myopathies are reported as a homogeneous disease entity with severe arrhythmia and slowly progressive proximal muscle weakness with lordotic posture, features which are irrespective of the presence of primary biliary cholangitis (PBC) [ 129 ]. Albayda et al reported a small cohort of seven AIM (DM and PM) with conventional AMA (M2 EP, MIT3) detected by ELISA [ 128 ].…”

“…A recent study concluded that mitochondria are central to skeletal muscle involvement and calcinosis of juvenile dermatomyositis (JDM) [ 135 ]. Last, Kainaga et al reported a 48-year-old female with myositis associated with PBC but without classical AMAs [ 129 ]. This and related observations summarized above suggest the importance at determining AMA in a more systematic approach as recently reported in SLE [ 136 ].…”