Rare forms of inflammatory myopathies – part I, generalized forms

ABSTRACT

Introduction

The idiopathic inflammatory myopathies traditionally comprise dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, anti-synthetase syndrome, and inclusion body myositis. In this review, we aimed to cover the less common forms of generalized myositis.

Areas covered

We identified rare forms of widespread myositis on the basis of list provided by the homepage of the Neuromuscular disease center of Washington University, USA and on the basis of the authors’ knowledge. We searched PubMed® and EMBASE® for relevant articles on these forms with the aim of providing as much as possible information on their clinical manifestations as well as guidance on their work-up and treatment.

Expert opinion

There is substantial heterogeneity among the various rare forms of generalized myositis in terms of their frequency and characterization. Some forms are reasonably well defined, while others may not represent truly well-defined diseases, but rather variants of other myopathies. The landscape of rare forms appears to have evolved over time, with some forms now being better characterized, while others, such as SARS-Cov-2- and immune checkpoint inhibitor-related myositis have come to the fore only in recent years. Knowledge about rare forms of myositis can aid in their recognition and treatment.

KEYWORDS:

• Myositis
• vaccines
• viruses
• granuloma
• eosinophils
• immune check point inhibitors
• graft versus host disease
• covid-19

Article highlights

• Myositis comprises some rare forms

• Some forms are induced by medications or associated with other diseases

• Rare forms may have unusual features compared to the traditional idiopathic inflammatory myopathies

• Knowledge about rare forms of myositis is essential to their recognition and tailored treatment

Declaration of interest

C Salvarani received consulting and investigator fees from Abbvie, Pfizer, MSD, Roche, Celgene, Novartis. N Pipitone received consulting and investigator fees from UCB, Fininvest, AIM group, I&C, Uptodate, Janssen-Cilag, Servier, GSK, AIFA, Foreum, Adienne. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Notes

1. Comment to: ”it was more frequent in patients, treated with PD-1 than anti-CTLA4 inhibitors treated with cytotoxic anti-cancer agents” Please amend to: ”it was more frequent in patients treated with PD-1 than anti-CTLA4 inhibitors and in patients treated with cytotoxic anti-cancer agents”.

Additional information

Funding

This paper was not funded.