# An atypical multiple autoimmune syndrome: A case report including myocarditis

## TL;DR

A young woman with rheumatoid arthritis and Sjögren's syndrome also developed autoimmune myocarditis, an unusual combination of three autoimmune conditions.

## Contribution

This case report highlights an atypical presentation of multiple autoimmune syndrome involving myocarditis.

## Key findings

- The patient had rheumatoid arthritis, secondary Sjögren's syndrome, and autoimmune myocarditis.
- Myocarditis is uncommon in rheumatoid arthritis and even rarer in Sjögren's syndrome.
- This case suggests a possible link between these autoimmune conditions.

## Abstract

The co-occurrence of autoimmune diseases has been epidemiologically studied and has contributed to our understanding of autoimmunity. The underlying mechanisms of this syndrome remain elusive; however, its prevalence may be higher than currently documented. The co-occurrence of at least 3 autoimmune diseases in a single patient has been defined as multiple autoimmune syndrome (MAS). This syndrome can be classified into 3 categories based on the prevalence of their associations with one another: type 1, type 2, and type 3. Myocarditis is classified as type 3, and typically does not present with connective tissue involvement. This report presents the case of a young female with known autoimmune disorders: rheumatoid arthritis (RA)and secondary Sjögren's syndrome (GSJ). The patient presented with MRI-confirmed myocarditis, likely of autoimmune origin, combining the 3 conditions in an atypical presentation. An additional noteworthy aspect of this case is the uncommon occurrence of myocarditis in rheumatoid arthritis, and even more so in Sjögren's syndromes.