Identification and management of pleural effusions of multiple aetiologies

The incidence of malignant and cardiovascular disease is increasing [1,2], and with it, the prevalence of the complex pleural patient. Patients often present with established comorbidities, such as cancer and benign lung disease, together with risk factors for cardiovascular, renal and metabolic disease, which all can interact with each other at the pathophysiological level [3]. This can make it difficult for the physician to identify the predominant cause of the patients’ symptomatology.

Whilst traditionally, a pleural effusion has been attributed to a single aetiology, there has been increasing recognition it may be a result of several interplaying disease processes. A recent study has supported this, demonstrating that 30% of the patients studied with a unilateral effusion had more than one underlying aetiology [4]. This is likely to be underappreciated because of current diagnostic algorithms and tools which are not designed to identify multiple causes [5]. The binary classification of transudates and exudates also encourages the notion that the effusion has a singular cause.

Recognition that multiple processes may be responsible and that establishing one diagnosis does not exclude other causes [6] is key in forming a comprehensive diagnosis. The identification of certain contributory causes clearly warrants changes in management approach, whilst in others the benefits are less clear [4].

New diagnostic algorithms, likely with an increased role of biomarkers, will be required to identify and manage the complex pleural effusion. This article will explore possible diagnostic approaches and subsequent treatment options for pleural effusions secondary to multiple aetiologies.