Perplexing pleural effusion.

Twenty-seven patients with perplexing pleural effusion were studied to determine clinical outcome. The value of performing pleuroscopic examination or open pleural biopsy (or both) in search of a diagnosis was assessed. After a mean follow-up period of six months, a diagnosis was reached in 16 patients, while 11 patients had no diagnosis after a mean follow-up period of 24 months. The causes for the effusions were neoplasm (eight patients), tuberculosis (one patient), blastomycosis (one patient), systemic lupus erythematosus (one patient), pulmonary infarction (two patients), and fractures of the ribs (three patients). The diagnosis was made by pleuroscopic examination or open biopsy in five patients, by autopsy in four, and by long-term follow-up studies in seven patients. When neoplasm or granulomatous disease was not suspected before surgery, pleuroscopic examination or open biopsy or both were nondiagnostic. These data support a policy of selecting patients for these procedures when a presumptive diagnosis of neoplasm or granulomatous disease is made but cannot be confirmed by less invasive methods. When the clinical data are too nonspecific to formulate a meaningful clinical impression, a more conservative approach is recommended.