Coexistence of Multiple Myositis-Specific Antibodies in Patients with Idiopathic Inflammatory Myopathies

Abstract

The mutual exclusivity of myositis-specific antibodies (MSAs) has been reported before, but the coexistence of 2 or more MSAs was still found in a few case reports. This study aims to confirm the existence and prevalence of double MSAs in patients with idiopathic inflammatory myopathy (IIM) and to clarify the clinical features of these patients. One hundred fifty-one patients with IIM diagnosed from 1 July 2018 to 31 July 2022, at National Cheng Kung University Hospital, Taiwan, were enrolled and divided into two groups, patients with ≤1 MSA (n = 128, 84.8%) and those with ≥2 MSAs (n = 23, 15.2%) according to the initial serology results. After being re-examined by ANA-IIF assay, 8 out of 23 patients were confirmed to have ≥2 MSAs. The demographic data and clinical features were presented. The prevalence of double-positive MSAs among IIM was 5.3% in this cohort. The coexistence of two MSAs in an IIM patient does exist but is rare. Patients with two MSAs belonging to two distinct IIM subtypes presented clinical features skewed to one subtype instead of “mixed phenotypes”. No apparent difference in clinical severity was found between patients with ≥2 MSAs and ≤1 MSA. Longer follow-ups and more studies are required to characterize the patients of IIM with ≥2 MSAs.

Idiopathic inflammatory myopathies: one year in review 2023

“…Although their true clinical value has yet to be defined, as they are common to other autoimmune disorders, antibodies to valosin-containing protein (anti-VCP) were detected in 26.0% of patients with sporadic IBM with a significant specificity (87.2%) but low sensitivity (26.0%) (83). Despite the fact that, in most cases, the coexistence of two or more MSAs represents a false positive, double positivity for MSAs is rare but may occur in IIMs, although the clinical phenotype is usually characteristic of only one of them and the double positivity does not seem to have an impact on the severity and prognosis of the disease (84). sparing agents, or both.…”

Clinical Manifestations and Prognosis of Anti-Signal-Recognition-Particle Myositis

“…Previous studies observed the coexistence of multiple MSAs in 3%–15% of patients with IIM, with the proportion varying with the test methods. 7 8 It is particularly interesting that the anti-Ro52 antibody has also been the most commonly detected myositis autoantibody in Korean patients with anti-HMGCR myopathy. 3 Further studies with larger study populations that apply multiple antibody detection methods are necessary to determine the clinical implications of the anti-Ro52 antibody in patients with seropositivity for IMNM.…”