Chest
Volume 130, Issue 1, July 2006, Pages 22-29
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Original Research
Quantitative Analysis of Fibroblastic Foci in Usual Interstitial Pneumonia

https://doi.org/10.1378/chest.130.1.22Get rights and content

Study objectives

Using semiquantitative scoring methods, several studies have shown that the amount of fibroblastic foci (FF), which are one of the pathologic characteristics in usual interstitial pneumonia (UIP), is a significant prognostic factor of UIP. In those studies, the degree of FF was evaluated semiquantitatively on several scales by a panel of pulmonary pathologists. However, the evaluation was somewhat subjective because interobserver variation was not small. Additionally, these methods are not entirely practical because two or more pathologists are required. In this study, we tried to develop a more quantitative scoring method of FF.

Patients and methods

With a charge-coupled device camera, we made images of lung sections obtained from 15 patients with UIP associated with collagen vascular disease (CVD) [CVD-UIP] and 16 patients with idiopathic pulmonary fibrosis (IPF) [IPF/UIP], and calculated the proportion of FF areas in the target image areas with an image analytic software.

Measurements and results

Our quantitative scoring method enabled us to readily and objectively evaluate the extent of FF as a quantitative percentage of FF area (%FF) score. Interobserver and intraobserver correlations were high in our method (r = 0.877 and r = 0.898, respectively). The quantitative %FF score (± SD) of IPF/UIP patients was 1.67 ± 0.90%, which was significantly higher than that of CVD-UIP patients (0.39 ± 0.24%, p < 0.0001). A Cox proportional hazards model showed that the quantitative %FF score was a significant predictor of survival in UIP patients. The quantitative %FF score had a correlation with scores assessed by the semiquantitative scoring methods previously reported, but patients with the same score assessed by the semiquantitative methods had widely varying scores assessed by our method.

Conclusions

These results suggest that our quantitative scoring method for FF is more objective than the semiquantitative scoring methods previously reported, providing accurate information about the prognosis of patients with UIP.

Section snippets

Study Population

We experienced consecutive 39 patients with interstitial pneumonia associated with CVD and 37 patients with idiopathic interstitial pneumonia who underwent open or thoracoscopic lung biopsy in our hospital between 1990 and 2003. Surgical lung biopsy slides were independently reviewed by two lung pathologists (S.I., N.E.) who were unaware of clinical or physiologic findings. When the classification differed between the pathologists, a consensus opinion on the overall histopathologic pattern was

Clinical Characteristics, Laboratory Findings, Pulmonary Function Testing, and BAL Findings

The clinical characteristics and laboratory findings of the patients with CVD-UIP and IPF/UIP are summarized in Table 1. There were no significant differences in clinical characteristics between CVD-UIP and IPF/UIP, although the proportion of female patients with CVD-UIP tended to be higher than that with IPF/UIP, and pack-years of smoking in IPF/UIP tended to be higher than those in CVD-UIP. In laboratory findings, serum surfactant protein-D levels of IPF/UIP were higher than that of CVD-UIP,

Discussion

The main aim of this study was to develop a more quantitative procedure for scoring the degrees of FF than the semiquantitative methods previously reported. Our scoring method using a CCD camera and analytic software enabled us to accurately measure the %FF, and evaluate the degree of FF as the quantitative %FF scores. Additionally, we found that our quantitative %FF score was an independent prognostic factor in patients with UIP in the Cox proportional hazards regression model. Interestingly,

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