Repeated thoracentesis: an important risk factor for eosinophilic pleural effusion?

Eosinophilic pleural effusion (EPE) is a relatively rare clinical condition. Repeated thoracenteses (RTs) are normally considered a frequent cause of EPE. Yet, to our knowledge, there is no firm evidence (apart from anecdotal case reports) supporting such a statement.

To investigate potential relationships between the number, type (with or without pleural biopsy) and time elapsed between RTs and the number of eosinophils present in pleural fluid samples.

We reviewed retrospectively 273 pleural fluid samples belonging to 120 patients (79 males, 41 females), attended in our institution from 1992 to 2000, whose clinical management had required RTs. Apart from the anthropometric and clinical data of each patient, we included the following variables in the analysis: number of thoracenteses performed in each individual, number of pleural biopsies carried out at each thoracentesis and time between consecutive thoracenteses. We also recorded the total (and differential) leukocyte count, red blood cell count, as well as the main biochemical, microbiological and histological data of both the pleural fluid and peripheral blood samples.

We did not observe any significant change in the percentage of eosinophils in relation to the number of thoracenteses performed per patient. This lack of relationship was also observed in the subgroup of patients who required one (or more) pleural biopsies (n = 111) (regardless of the number of biopsies). Our results suggest that RTs are not an important risk factor for the development of EPE, regardless of the time elapsed between two thoracenteses.

We believe, therefore, that multiple punctures should not longer be considered a prevalent cause of pleural eosinophilia.