Abstract

Diffuse interstitial lung disease(DILD) is a large group of heterogeneous diseases that diffusely involve the pulmonary connective tissues, principally subpleural, interlobular and alveolar wall portions. Terminology and classification of these diseases are not uniform, and the cause and the pathogenesis are unknown in many entities. It is generally accepted that the response to therapy is related to the relative degree of cellularity and fibrosis present, therefore a histologic evaluation of the relative extent and severity of these changes is required. We reviewed 52 cases of DILD from January 1990 to May 1995 diagnosed by open lung biopsy to reappraise classification and quantitative assessment of the histopathologic features. Differential histopathologic features between usual interstitial pneumonia(UIP) and nonspecific interstitial pneumonia(NIP) were examined with a correlation of HRCT findings and clinical findings. Among 52 cases of DILD, 18 cases(34.6%) were UIP, 6 cases(11.5%) were hypersensitivity pneumonia was NIP was 5 cases(9.6%), interstitial lung diseases associated with the connective tissue diseases were 5 cases(9.6%), inorganic dusts were 4 cases(7.7%), infections were 4 cases(7.7%), durgs were 2 cases(3.8%), acute interstitial pneumonia was 1 case(1.9%), sarcoidosis was 1 case(1.9%) in order of frequency plus 6 other cases(11.5%). UIP was the most frequent DILD in this study which seemed to be a criteria bias of patient selection on open lung biopsy. Quantitative assessment of histopathologic features was useful in the differential diagnosis of DILD and differentiation of UIP from NIP was possible based on histopathologic features and supported by HRCT. UIP disclosed a significantly high score of fibrotic changes, especially in the interstitial fibrosis, smooth muscle proliferation and honeycombing, otherwise NIP appeared relatively high score in inflammatory changes. Correlation between histopathologic scores and the clinical outcome after steroid therapy or no therapy in UIP was not evident.

• Keywords: Diffuse interstitial lung disease;Classification;Quantitative assessment;Steroid therapy;