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The Overlap Between Respiratory Bronchiolitis and Desquamative Interstitial Pneumonia: Conclusion

The Overlap Between Respiratory Bronchiolitis and Desquamative Interstitial Pneumonia: ConclusionOur study suggests that in some individuals with PLCH, extensive RB/ DIP-like changes may be the lesion responsible for the majority of physiologic and clinical abnormalities, rather than the lesions of PLCH. Irrespective of how one defines the final pathologic lesion, it is clear that the entire spectrum of smoking-related interstitial lung injury may be sometimes seen in the same patient, albeit to different degrees (Fig 3).
Several studies have illustrated the utility of HRCT in the diagnostic workup of PLCH. This study and others illustrate the overlap between different radiologic patterns of smoking-induced interstitial patterns of injury, and the need for caution in establishing a diagnosis of these diseases without lung biopsy. We report the occurrence of ground-glass attenuation on HRCT, which may be indicative of significant associated RB/DIP. The only other study describing the presence of ground-glass attenuation in patients with PLCH is the one by Brauner et al, who reported the occurrence of ground-glass attenuation in 4 of 18 patients with PLCH. Reading here
Although we identified 3 cases in the current series of 14, retrospective review of our database of PLCH cases indicates that ground-glass attenuation is an uncommon finding. In our database, we identified an additional 34 patients with PLCH who underwent CT in the diagnostic workup: 15 patients had HRCT alone for diagnosis, and 19 patients had HRCT and biopsy but radiographs and/or biopsy specimens were unavailable for review. Of this additional group of patients, only one patient was originally reported to have ground-glass attenuation (open-lung biopsy-confirmed PLCH). Thus, ground-glass attenuation is probably an uncommon radiographic manifestation in patients with PLCH.
In conclusion, the current study confirms that RB/DIP-like changes are exceedingly common in patients with PLCH, and are a reflection of lung injury associated with cigarette smoking. Some patients with PLCH have a marked component of RB/DIP-like changes, which may be associated with ground-glass attenuation on CT. Ground-glass attenuation and mild adenopathy are radiographic findings that may occur in PLCH and cause diagnostic difficulty. This study provides further evidence that smoking can cause the whole spectrum of RB, DIP, and PLCH in predisposed individuals.