[The significance of subpleural mononuclear cell infiltration in the differential diagnosis of pleurisy showing nonspecific histological findings].

To determine whether or not patients who showed abundant lymphocytes in pleural effusion without any specific findings by pleural biopsy could be histopathologically differentiated between those with tuberculous and nontuberculous origin, we reexamined histology of pleural biopsies of all patients whose pleural effusion showed predominantly lymphocytes and did not contain malignant cells from January, 1984 to March, 1989. A total of 45 patients with a nonspecific histology of pleural biopsy were categorized based on their final diagnosis into three groups; tuberculous (n = 20), carcinomatous (n = 10) and nontuberculous, benign pleurisy (n = 15). Pleural biopsy of patients with nontuberculous, benign pleurisy frequently showed band-like infiltration of mononuclear cells in the subpleural adipose tissue (11 out of 15 patients), while the finding was significantly less frequent in those with tuberculous pleurisy (1 out of 20, p less than 0.01) and pleurisy associated with carcinoma (3 out of 10, p less than 0.05). Based on these findings, the presence of band-like infiltration of mononuclear cells in the subpleural adipose tissue in pleural biopsy of patients with abundant lymphocytes in pleural effusion strongly suggests that the pleurisy is nontuberculous origin.