The requirement for compensation for diffuse pleural thickening in benign asbestos pleural effusion include five computed tomography findings of organized pleural effusion: [1] heterogeneity in the pleural effusion, [2] declined chest capacity, [3] "crow's feet" sign at the pleura, [4] immobilization of effusion volume, and [5] air in the effusion. Pleural effusion is diagnosed as organized, immobilized, and in the state of diffuse pleural thickening if at least three of these items are fulfilled, ([1] and [3] compulsory + one of the remaining items). This retrospective study investigated whether the requirement to confirm no organized pleural effusion changes after a follow-up of >3 months were available for cases fulfilling three of the five items; i.e., the confirmation of only [2] with [1] and [3]. Of 302 cases recognized by the Japanese laws, 105 cases with diffuse pleural thickening with organized effusion were enrolled. The number of subjects who fulfilled the diagnostic requirement for organized pleural effusion was confirmed. Eight subjects had a full score of 5 points, 82 subjects scored 4 points, and only 15 subjects scored 3 points. Furthermore, no changes were observed in the organized pleural effusion volume after a follow-up of >3 months.
Keywords: Benign asbestos pleural effusion; Crow’s feet sign; Diagnostic criteria; Diffuse pleural thickening; Heterogeneity in the pleural effusion; Organized pleural effusion.