© 2009 American Thoracic Society
Understanding Nonspecific Interstitial Pneumonia: The Need for a Diagnostic Gold StandardFrom the Authors:We appreciate Dr. Maher's and Drs. Wuyts and Verleden's comments about our article (1). As reported, we point out that the nonspecific interstitial pneumonia (NSIP) pattern can be seen in other conditions, such as hypersensitivity pneumonitis (HP), connective tissue disease (CTD), and drug toxicity, and that there is some overlap with cryptogenic organizing pneumonia, usual interstitial pneumonia/idiopathic pulmonary fibrosis, and respiratory bronchiolitis–interstitial lung disease. However, we disagree with Dr. Maher that it is "likely that the remaining cases of apparently idiopathic NSIP simply represent occult manifestations of these other diseases" (2). We also do not agree that this is "borne out" by the microarray study of Selman and colleagues, where they found two of eight cases of NSIP that had an IPF-like gene expression and one of eight that had gene expression similar to HP (see Reference 4 of Dr. Maher's letter). Although provocative, these data do not support Dr. Maher's belief that all cases of idiopathic NSIP are occult manifestations of other diseases. In our article, we outlined other future studies required to better understand NSIP. We are pleased to see such data emerging with clinical and genetic studies comparing idiopathic NSIP with other interstitial disorders and investigation whether NSIP is an autoimmune disease. For example, Kinder and coworkers reported that 88% of their cases of idiopathic NSIP had manifestations of an undifferentiated CTD (UCTD) (2). For our study, we did not have complete data regarding specific CTD manifestations in all patients; however, positive serologies (ANA or rheumatoid factor) or rheumatologic symptoms were common. Whether UCTD can consistently be demonstrated in such a high percentage of cases, as found by Kinder and colleagues, needs further investigation. Further, it remains to be determined if a diagnosis of UCTD should require that the term "idiopathic" be removed from all cases of previously diagnosed idiopathic NSIP. Despite its limitations, the clinical-radiologic-pathological (CRP) approach is the gold standard for diagnosis of idiopathic interstitial pneumonias (1, 3) and, as Drs. Wuyts and Verleden suggest in their letter, it is also useful for other diffuse parenchymal lung disorders. We hope that in the near future our understanding of these disorders will be advanced by genetic and epidemiologic studies based on the foundation of careful CRP diagnoses.
Memorial Sloan Kettering Cancer Center
Mayo Clinic
University of Maryland
University of Iowa
University of California, San Francisco
National Jewish Medical Research Center On Behalf of the ATS NSIP Project Committee FOOTNOTES Conflict of Interest Statement: W.D.T. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. T.V.C. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. J.R.G. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. G.H. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. T.E.K. has served on advisory boards for Actelion, InterMune, and GlaxoSmithKline, and served as a consultant for Nektar, Alexza, AstraZeneca, Biogen, Centocor, Fibrogen, Genzyme, Human Genome Sciences, Merck, and CoTherix. D.A.L. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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