Chest
Volume 138, Issue 2, August 2010, Pages 251-256
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Commentary
Connective Tissue Disease-Associated Interstitial Lung Disease: A Call for Clarification

https://doi.org/10.1378/chest.10-0194Get rights and content

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.

Section snippets

Implications of the Diagnosis

In our opinion, numerous implications of identifying underlying systemic autoimmune disease in patients presenting with an IP exist. Most significantly, CTD-IP is associated with a more favorable prognosis than IIP.1 Although it is not known whether the identification of occult forms of CTD carries a similarly more-favorable prognosis, it can be argued that future decisions that incorporate the knowledge of underlying autoimmunity might well promote an improved understanding of pathogenesis and

Challenges and Limitations

Although all pulmonologists see patients in whom they suspect an underlying autoimmune mechanism as the cause of the pulmonary disease, confirming systemic autoimmune disease and diagnosing specific CTDs in the absence of classic clinical findings are challenging,2, 3 and we believe that current screening strategies are largely inadequate. Detecting CTD by simply screening with nonspecific autoantibodies does not suffice,2, 3, 4, 5, 6 and current rheumatologic classification schemes are

Identifying Occult CTD

We believe that the detection of occult CTD in patients presenting with IP is optimized by multidisciplinary collaboration. Finding occult CTD is not uncommon. It has been estimated that among patients presenting with an apparently IIP, roughly 15% are found to have underlying CTD after more thorough evaluation.5 Homma and colleagues7 evaluated whether IP as the sole presentation of CTD can be differentiated from IIP. They described 68 patients who had presented with IIP and were followed

Redefining Undifferentiated CTD Is Problematic

The concept has been proposed that all patients with idiopathic NSIP, even those without extrathoracic features or serum autoantibodies, actually have an undifferentiated CTD (UCTD).13, 15 In our opinion, although this hypothesis is interesting, the revised application of this CTD diagnosis to encompass all NSIP cases is problematic. Redefining the UCTD diagnosis in this way requires input from rheumatologists who are generally skeptical about accepting IP as a diagnostic criterion for CTD. For

Some Proposed Solutions

In the face of the challenges posed by these disorders that fall short of universally acceptable diagnoses and of discordant perceptions about disease classification as well as the impasse in accepting the redefining of UCTD, we offer the following modest suggestions.

Conclusions

We believe that multidisciplinary collaboration in the evaluation of IP and testing the concept of lung-dominant CTD ultimately will allow more precise disease differentiation to be made and might lead to a better understanding of IP. In addition, it can be argued that future decisions that incorporate the knowledge of lung-dominant CTD might well lead to the development of more targeted therapies as well as affect treatment choices. Further research is needed to validate the proposed

Acknowledgments

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

References (17)

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