PURPOSE: Desquamative interstitial pneumonia (DIP) is a subtype of idiopathic interstitial pneumonia that responds well to steroid therapy and generally has a good prognosis. However, compared to idiopathic pulmonary fibrosis, the frequency of its occurrence is very low, and although there are occasional reports regarding its histological characteristics and related bronchoalveolar lavage fluid (BAL) fluid findings, the details of its pathological conditions are still unknown.
METHODS: To examine the clinical and pathological features of patients with DIP, we retrospectively evaluated 26 pathologically definite DIP cases, including 19 cases previously-reported from Japan, plus 7 cases in our department.
RESULTS: Only one case was a current smoker in our 7 cases. High serum levels of IgG or positive findings for some kind of autoantibodies were observed in 20 cases. Most of these 20 cases showed eosinophilia and neutrophilia in the BAL fluid. The pulmonary manifestation preceded the onset of rheumatoid arthritis in one case. In addition, 4 cases in 7 cases from our department had elevated serum levels of lysozyme. In an immunohistochemical analysis of the lung, increased expression of lysozyme were found in the neutrophils and the aggregated alveolar macrophages.
CONCLUSION: DIP is considered to be a smoking-related IP in the majority of cases, however, our results suggest the possibility that the DIP pattern is an additional form of IP that may develop in association with autoimmune diseases, and also suggest that elevated serum levels of lysozyme can occur in diseases such as DIP in which the macrophage and neutrophil activity may be involved in the pathological condition.
CLINICAL IMPLICATIONS: As the pathogenesis of DIP has not yet been elucidated and may also include heterogeneous subtypes, further studies are required.
DISCLOSURE: Hiroshi Ishii, No Financial Disclosure Information; No Product/Research Disclosure Information