Benign asbestos pleural effusion: diagnosis and course.

We have reviewed 22 patients with benign asbestos pleural effusion seen over a 17-year period. The mean duration of exposure to asbestos was 5.5 years and the mean interval between exposure and presentation was 16.3 years. In five the effusion was asymptomatic. Fever was uncommon but in 15 of 21 patients the ESR was elevated. Leucocytosis was noted in seven of 20 patients. Autoantibodies were rarely detected. The pleural fluid was usually blood-stained and the volume aspirated was rarely larger than 500 ml. Pleural biopsies revealed established pleural fibrosis and/or inflammatory infiltration with fibrinous exudate and mesothelial and fibroblastic proliferation. A positive mantoux test was noted in eight of 12 patients but there was no other evidence of tuberculosis. The mean duration to spontaneous resolution of the effusion was 4.3 months. During a follow-up period of 28.1 years from initial exposure to asbestos (mean 22.8 years) and up to 17.2 years from initial presentation with a pleural effusion (mean 6.3 years) seven patients had a single recurrence and only one patient had multiple pleural effusions. Only three patients experienced persistent pleural pain. It was not possible to predict the likelihood of recurrence of an effusion or the persistence of pleural pain from the data at presentation. No patient subsequently developed mesothelioma or other neoplasm.