A narrative review of malignant eosinophilic pleural effusion: incidence, etiology and prognostic significance

Abstract

Eosinophilic pleural effusion (EPE) is defined as a pleural fluid with an eosinophilic count exceeding 10% and currently considered to be mainly caused by malignancy. However, the incidence, etiology and prognostic significance of malignant eosinophilic pleural effusion (MEPE) have not been studied extensively yet. Thus, the objective of this review was to summarize medical studies regarding MEPE to 2020 throughout an extensive search of PubMed. Overall, MEPE was a disease associated with multiplecytokines-mediated immunity and varied from 4% to 92% of patients who had EPE. The discrepancy of the MEPE prevalence among studies could be explained by the development of diagnostic technology, disparity of study population, or various disease spectrum over time. Data summarized in this review demonstrated that the incidence of malignancy was lower in EPEs than in non-EPEs (29.7% vs. 32.9%). Additionally, MEPE could be a manifestation of a great variety of tumor subtypes, among which lung cancer was the most common cause and accounted for more than 34% of cases. The second common causes were non-Hodgkin lymphoma and metastatic cancers with unknown primary site which were observed in around 5% of cases, respectively. The presence of eosinophils in the pleural effusion may be associated with a positive prognosis of MEPE. Besides, the prognosis of MEPE may be related to the percentage of eosinophils in the pleural fluid. More extensive studies, however, are warranted to validate these findings.

Incidence, Aetiology and Clinical Features of Eosinophilic Pleural Effusion: A Retrospective Study

“…Wysenbeek's study showed that the aetiologies of EPE were trauma (39%), congestive heart failure (14%), infection (8.5%) and idiopathic effusion (8.5%) [9]. The differences in results may be explained by the different prevalences of the aetiology of PE at some institutions [10]. Although there was no drug-induced EPE in our study, the list of possible aetiologies has been increasing in recent years, including methimazole, carbimazole, valproic acid, mesalamine, olanzapine and others [11][12][13][14][15][16].…”

Hodgkin’s Lymphoma as an Unusual Cause of Eosinophilic Pleural Effusion

“…A recent review study conducted by Li and his colleagues found malignancy to be the commonest cause of EPE [7], and its incidence has a close relationship with the population being studied and the diagnostic criteria being used. Among the causes of malignant EPE, lung cancer was found to be the leading cause with 23 reported cases, followed by non-Hodgkin lymphoma and metastatic carcinoma of unknown origin, each comprising 5% of total reported cases of malignant EPE [7]. Hodgkin's lymphoma is a rare cause of malignant EPE with only two reported cases [8,9].…”

“…An overwhelming number of recently published studies have demonstrated that the prevalence of malignancy could be as frequent in EPEs as in non-EPEs and that there is no statistically significant difference in the incidence of malignant neoplasm between the two [7].…”

“…With regard to clinical characteristics, patients with malignant pleural effusion tend to have a longer duration of symptoms than those with EPEs of benign pathologies [7]. The symptoms are usually cough, shortness of breath, chest discomfort, hemoptysis and weight loss, although asymptomatic presentations are also seen among a number of affected patients [7].…”

“…Most of the malignant EPE cases fail to respond to the available treatment options, and the current strategies are only used to provide symptomatic relief. These strategies include radiotherapy, chemotherapy, indwelling pleural catheter and thoracoscopy with pleurodesis [7]. With regard to disease prognosis, patients with malignant EPEs have a better prognosis than those with non-EPE malignancies, and in addition, higher eosinophilic count is shown to be associated with improved overall survival rates among patients with malignant EPE [7].…”