Malignancy screening in autoimmune myositis among Australian rheumatologists

Rheumatologische paraneoplastische Syndrome

Rheumatologische paraneoplastische Syndrome sind selten, stellten jedoch eine wichtige Differenzialdiagnose zu klassischen rheumatologischen Krankheitsbildern dar. Durch das Erkennen der eindrücklichen Syndrome mit typischen Labor- und Untersuchungsbefunden ist oftmals eine beschleunigte Diagnose der zugrundeliegenden Malignität und kurative Therapie möglich. In dieser Übersichtsarbeit werden die Charakteristika rheumatologischer paraneoplastischer Syndrome vorgestellt.

The diagnostic work-up of cancer-associated myositis

PURPOSE OF REVIEW

Despite the well-recognized association between malignancy and myositis, definite data indicating the best strategy for diagnosing cancer in myositis patients is lacking. In this article, we review the data on cancer screening in patients with myositis, and propose an algorithm for this purpose based on recently published data.

RECENT FINDINGS

Evidence has recently emerged supporting blind screening in patients with certain myositis phenotypes. In addition to the clinical examination, imaging techniques such as PET/computed tomography scanning and whole-body MRI, and determination of the autoantibody profile beyond anti-TIF1γ antibody, the well known cancer biomarker in dermatomyositis, will help the clinician face this complex clinical situation. Molecules related to the checkpoint inhibitor pathway, specifically soluble programmed death 1, may also have a role in the diagnostic work-up of cancer in myositis. In the future, blood tests analysing circulating DNA will certainly help in detecting patients with cancer-associated myositis (CAM).

SUMMARY

A step forward has been achieved in the pathway to establish optimal cancer screening for myositis patients. International consensus guidelines for an effective diagnostic work-up of CAM are in progress and will be of paramount importance to improving the outcome in these patients.

Autoantibodies in myositis

The discovery of novel autoantigen systems related to idiopathic inflammatory myopathies (collectively referred to as myositis) in adults and children has had major implications for the diagnosis and management of this group of diseases across a wide range of medical specialties. Traditionally, autoantibodies found in patients with myositis are described as being myositis-specific autoantibodies (MSAs) or myositis-associated autoantibodies (MAAs), depending on their prevalence in other, related conditions. However, certain MSAs are more closely associated with extramuscular manifestations, such as skin and lung disease, than with myositis itself. It is very rare for more than one MSA to coexist in the same individual, underpinning the potential to use MSAs to precisely define genetic and disease endotypes. Each MSA is associated with a distinctive pattern of disease or phenotype, which has implications for diagnosis and a more personalized approach to therapy. Knowledge of the function and localization of the autoantigenic targets for MSAs has provided key insights into the potential immunopathogenic mechanisms of myositis. In particular, evidence suggests that the alteration of expression of a myositis-related autoantigen by certain environmental influences or oncogenesis could be a pivotal event linking autoantibody generation to the development of disease.

Immune-mediated necrotising myopathy: A critical review of current concepts

Immune-mediated necrotising myopathy (IMNM) is a relatively recently described form of idiopathic inflammatory myopathy (IIM) that is characterised by progressive proximal weakness and few extra-muscular manifestations. Prominent myonecrosis, muscle fibre regeneration and a relative paucity of intramuscular lymphocytes are seen histologically. Immunological mechanisms are believed to underpin the pathogenesis, and intense immunotherapy is frequently required. Disease is often severe and neuromuscular recovery may be poor. Recently there has been an impressive international research effort to understand and characterise this emerging condition, although much remains unknown. Significant advances in the field include the discovery of specific autoantibodies, increased understanding of the risk factors, clinical characteristics and treatment options owing to a wealth of observational studies, and the development of novel classification criteria. Herein we review the current evidence regarding the pathophysiology, clinical presentation, histological features and serological profiles associated with this condition. Diagnostic approaches are discussed, including the role of muscle MRI and antibodies targeting 3‑hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and signal-recognition peptide (SRP), and a review of current treatment recommendations is provided.