Myositis Antibodies and Interstitial Lung Disease

BACKGROUND

Interstitial lung disease (ILD) comprises a heterogeneous group of inflammatory and fibrotic conditions, often resulting in progressive lung function decline and increased mortality. Connective tissue disease (CTD) should be considered in all patients with ILD, as distinguishing between CTD-ILD and other forms of fibrotic lung disease has important therapeutic and prognostic implications. The idiopathic inflammatory myopathies (IIM) represent a CTD subtype of growing interest to ILD experts. The expansion and availability of myositis-specific and myositis-associated antibody testing has allowed for improved disease detection and characterization.

CONTENT

In this review, we highlight the relationship between myositis antibodies and ILD. Select forms of IIM, such as the antisynthetase syndrome and clinically amyopathic dermatomyositis can present with rapidly progressive ILD, warranting timely disease diagnosis and management. Disease phenotypes, prevalence, laboratory testing, prognosis, and management strategies are described according to select myositis antibodies.

SUMMARY

Myositis antibodies provide valuable information for clinicians managing patients with ILD. This review aims to increase awareness of their role in disease detection, pathophysiology, and possibly therapeutics.

Interstitial pneumonia with autoimmune features and platypnea-orthopnea syndrome

Interstitial pneumonia with autoimmune features (IPAF) is a recently proposed terminology for interstitial lung disease (ILD) with evidence of autoimmunity that does not meet the criteria for a defined connective tissue disease (CTD). Although ILD is well recognised in patients with established CTD, it is rarely the sole presenting feature of CTD. We report a case of 22-year-old male patient, who presented with progressive shortness of breath for 2 months and had features suggestive of platypnea-orthodeoxia syndrome (POS). Imaging revealed ILD with usual interstitial pneumonia pattern. Patient had features of autoimmune disorder but did not fulfil the criteria for any CTD and hence was labelled as IPAF. His POS was attributed predominantly to the lower lobe disease. The patient responded well to immunosuppressive treatment. A systematic review of literature of all cases with POS due to pulmonary parenchymal involvement has also been done.