Constrictive pericarditis presenting as pleural effusion of unknown origin.

Despite the known association of pleural effusion with constrictive pericarditis, the presentation of constrictive pericarditis as pleural effusion of unknown origin has, to our knowledge, never been described. After evaluating such a case, we retrospectively analyzed all cases of established constrictive pericarditis seen in this institution in the last six years. The clinical and laboratory features of this cohort of 30 patients are similar to those of other reported series. Pleural effusion was present in 18 (60%) of 30 cases. In six (12%) of the 18 cases, pleural effusion was a major component of the clinical presentation, and in three (10%) of these six cases, the persistence of pleural effusion of unknown origin was the indication for referral to this institution. Analysis of pleural fluid in four cases revealed three exudates and one transudate. We believe this is the first report of unexplained pleural effusion as the presenting manifestation of constrictive pericarditis, and this diagnosis should be added to the list of causes of unexplained pleural effusion.