Connective Tissue Disease-Associated Interstitial Lung Disease

Abstract

This commentary highlights the present dilemmas surrounding the classification of a patient with interstitial pneumonia who has clinical features suggesting an associated connective tissue disease but the features fall short of a clear diagnosis of connective tissue disease-associated interstitial lung disease under the current rheumatologic classification systems. This commentary illustrates what we perceive to be the limitations in the present approach to the classification of this group of patients and discusses problems with redefining the diagnosis of undifferentiated connective tissue disease to encompass patients with interstitial pneumonia. Finally, we advocate not only for a multidisciplinary approach to evaluation, but also disease classification and offer a proposal to define them as a distinct phenotype--lung-dominant CTD--for which prognostic, therapeutic, and pathobiologic implications can be tested in future, hopefully multiinstitutional, studies.

An official European Respiratory Society/American Thoracic Society research statement: interstitial pneumonia with autoimmune features

“…Specifically, it is unclear whether results from a study using any one of the previously published criteria [19][20][21] is comparable to other studies using a different set of criteria. With IPAF, uniform terminology and classification criteria for related but potentially distinct entities (UCTD-ILD, lung-dominant CTD and autoimmune-featured ILD) have been systematically developed and ratified.…”

“…Previously published terms describing this patient group, including broad and strict forms of UCTD-ILD, lung-dominant CTD and autoimmune-featured ILD [19][20][21], should be abandoned and replaced with consensus-derived nomenclature.…”

“…A number of recent studies have shown that many patients diagnosed with an IIP have certain, often subtle, clinical features that suggest an underlying autoimmune process and yet do not meet established diagnostic criteria for any characterisable CTD [19][20][21][22]. In some patients, these features may occur in the absence of serologic abnormalities, while in others, a highly specific serum autoantibody may be present without typical systemic or extrathoracic findings.…”

“…In other scenarios, radiologic or histopathologic features suggest an underlying CTD, but the absence of extrathoracic clinical or serologic findings precludes reliable classification of these patients as anything other than IIP. Such individuals have been described as having an autoimmune or rheumatologic "flavour" [20].…”

“…Researchers around the world have proposed differing, but overlapping, criteria and terms to describe these patients, including "undifferentiated CTD associated ILD" (UCTD-ILD) [19], "lung-dominant CTD" [20] or "autoimmune-featured ILD" [21]. Each term is controversial, none has been universally accepted, and because of their subtly different diagnostic criteria, each would include many of, but not all, the same patients.…”