Histologic Features of the Lungs
Fibrosis: Peribronchiolar fibrosis was identified in 49 (53 percent) of the 93 patients with pleural plaques and in 36 (39 percent) of the 93 control patients (Table 2). The mean peribronchiolar fibrosis product in the group with pleural plaques (1.45) was significantly (p<0.001) greater than that in the control group (0.68). Peribronchiolar fibrosis product was not significantly different for patients with and without a smoking history.
The relative degrees of alveolar, interstitial, and large scar fibrosis were also evaluated. Alveolar fibrosis (organizing pneumonia) was identified in 22 of the cases with pleural plaques (mean score, 0.39) and in 11 of the control cases (mean score, 0.17). This difference was significant (p<0.05). Similarly, the degree of large scar fibrosis was also more severe in the patients with pleural plaques (p<0.02) than in the controls. Large scar fibrosis was identified in 38 of the control patients (mean score, 0.56), while 53 of the cases with pleural plaque had large scars (mean score, 0.85). comments
Differences in interstitial fibrosis were, however, not significant. Sixteen of the control cases (mean score, 0.24) and 22 of the cases with pleural plaques (mean score, 0.40) showed this change.
Emphysema: The relative degrees of centrilobular and scar-related emphysema were graded in each case, with the understanding that emphysema is difficult to diagnose on histologic grounds alone when the sections are not prepared from lungs fixed in distention. Centrilobular emphysema was seen in both cases and controls with about equal frequency (32 cases and 28 cases, respectively), and the degree of centrilobular emphysema present in these cases was not significantly different (mean score of 0.46 vs 0.45). In contrast, scar-related emphysema was more common in the cases with pleural plaques (21 cases) than the controls (nine cases), and scar-related emphysema was more severe (mean score of 0.31 vs 0.12) in the cases with pleural plaques. This difference was statistically significant (p<0.02).
Table 2—Comparison of Pulmonary Parenchymal Pathologic Findings
|Histologic Feature||93 Patients with Pleural Plaques||93 Control Subjects||p Value*|
|No. Positive||Mean Grade of All Cases||No. Positive||Mean Grade of All Controls|
|Large scar fibrosis||53||0.89||38||0.56||p<0.02|