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The Overlap Between Respiratory Bronchiolitis and Desquamative Interstitial Pneumonia: HRCT

The Overlap Between Respiratory Bronchiolitis and Desquamative Interstitial Pneumonia: HRCTWhen present, the distribution of the abnormalities such as adenopathy and emphysema was recorded. Surgical lung biopsy specimens were reviewed by a pathologist (T.V.C.) blinded to the findings on HRCT. Accumulation of pigmented macrophages in airspaces and around respiratory bronchioles was combined with more widespread airspace accumulation of macrophages (DIP-like change) as RB/DIP-like change. This score provided a rough quantification of the degree of airspace filling (both respiratory bronchiole and alveolar spaces) by macrophages. The extent of involvement of the biopsy by RB/DIP-like changes was classified by percentage (0 to 100%).
A similar scoring system (0 to 100% involvement of biopsy) was used to quantify emphysema and alveolar septal fibrosis. The percentage estimates of RB/DIP-like changes and fibrosis were based on assessment of the total tissue area involved on all the tissue sections available for review. The fibrosis was considered to be related to PLCH when it was nodular or stellate in character, as is classic for PLCH. In many cases, Langerhans cells were present in these zones of fibrosis. Scarring was presumed to be related to RB/DIP when it was characterized by fine widening of alveolar septa with or without associated airspace enlargement The severity of cysts was scored by a 0-to-3 point system (0 = absent, 1 = mild, 2 = moderate, 3 = severe involvement).
To correlate findings between histology and HRCT, the extent of RB/DIP lesions observed on HRCT and histology were compared. Specifically, we wanted to define the frequency and extent of involvement of the biopsy specimens with RB/DIP, and correlate the extent and severity of RB/DIP-like changes with the presence of ground-glass attenuation on the HRCT. In addition, because RB/DIP are lesions associated with smoking, we correlated the extent of RB/DIP-like changes with total pack-years smoked at the time of biopsy.