Study objectives: To characterize the biochemical and
cytologic constituents of pleural effusions secondary to pulmonary
Design: A descriptive clinical study.
Setting: A community teaching hospital with 750 beds, which
acts as a tertiary referral center for several subspecialties.
Patients and interventions: Patients with pleural effusions
secondary to pulmonary embolism who underwent diagnostic thoracentesis
during the last 7 years were retrospectively studied. Pleural fluid
mesothelial hyperplasia was revised and compared with that found in
patients with pleural effusions of different origin.
Results: Pleural effusions from all 60 patients with
pulmonary embolism were exudates, and in 40 patients (67%) contained
erythrocyte counts > 10,000/μL. A bloody appearance was not related
to the use of anticoagulant therapy before thoracentesis.
Polymorphonuclear leukocytes were predominant in 36 patients (60%); in
11 patients (18%), a proportion of eosinophils > 10% was found.
Mesothelial hyperplasia was significantly higher in patients with
pulmonary embolism than in patients in the control group
(p < 0.01).
Conclusions: In the absence of trauma,
a bloody or eosinophilic effusion with a marked mesothelial hyperplasia
should prompt a workup to rule out embolism. The finding of
transudative pleural fluid chemistries in these patients should not be
assumed to be secondary to embolism before ruling out other causes of