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PEER REVIEW: PLEURAL EFFUSION
Malignant Pleural Effusion: Diagnosis and management Written by P. Ridge; D Breen - Interventional Respiratory Unit, Galway University Hospital Corresponding Author: Padraic Ridge, Galway University Hospital, Newcastle, Galway, Ireland Email: P.macaniomaire1@gmail.com Abstract: Malignant pleural effusion (MPE) is a common clinical entity affecting 40,000 people per year in the UK. MPE can occur with a primary pleural malignancy, typically mesothelioma or more commonly as a metastatic manifestation of a non pleural primary malignancy. In Ireland mesothelioma is an infrequent diagnosis and therefore the majority of cases of MPE represent advanced Stage IV malignant disease.1 In this paper we will review the diagnosis and subsequent management of MPE. This has important implications for staging and treatment of individuals.9
Dr Padraic Ridge
Dr David Breen
Introduction
The size of the effusion does not reliably predict a patients symptom burden as the fluid can accumulate gradually over time allowing the patient to compensate. Symptoms are more strongly correlated with the rate of fluid accumulation.7
Malignant pleural effusion (MPE) is defined by malignant cells within the pleural space. The pleural space can be involved by malignancy through direct extension of tumour, haematogenous spread or through primary pleural malignancy (mesothelioma).2,3 While any cancer can metastasize to the pleural space the most common in descending order are lung, breast, lymphoma, ovarian and gastric cancer. These account for approximately 80% of MPE.4,5 The incidence of MPE In the UK is circa 40,000 people/year. Median survival from diagnosis of MPE ranges from 3-12 months depending on the tumour type.5 Metastatic involvement of the pleural space by lung cancer is associated with the shortest median survival of 3 months, however novel targeted therapies may improve this prognosis.4 6 Presentation Patients may present with dyspnoea, orthopnoea or chest pain. Dyspnoea can be very severe and dramatically affect quality of life. However Individuals can often be relatively asymptomatic and MPE may only be incidentally picked up on routine imaging studies.4
Diagnosis It is important to note that 50% of pleural effusion in the setting of individuals with cancer are non-malignant.8 These may be caused by bronchial obstruction from tumour or benign causes such as congestive heart failure or infection. These are termed paramalignant or non-malignant pleural effusions. See Figure 1. Figure 1 Fig 1.
Causes of paramalignant effusions Direct tumour effect: -Lymphatic obstruction -Bronchial obstruction -Trapped lung -Chylothorax -Superior vena cava obstruction Systemic effects: -Pulmonary embolism -Hypoalbuminemia Complications of therapy: -Radiotherapy -Chemotherapy
AUGUST 2022 • HPN | HOSPITALPROFESSIONALNEWS.IE
Malignant pleural involvement should never be presumed and it is crucial to pathologically stage pleural effusions in the setting of malignancy. Malignant involvement of the pleural space implies stage 4 malignancy thus radical treatment options such as surgery are not an option. For those with para-malignant effusions radical, curative treatments may still be an option.10-12 Assuming malignant involvement in those with a paramalignant effusion could wrongly deny them potentially curative treatment. Imaging Chest radiography (CXR): Is the initial imaging for most. The standard posterior-anterior (PA) CXR will only start to become abnormal in the presence of approximately 200ml of pleural fluid.13 The initial sign is costophrenic blunting, which may progress to opacification with a meniscus or even a full “white
out” with tracheal deviation away from the effusion.13,14 Lateral films are more sensitive and can detect pleural effusions of 50ml.13 Ultrasound (US): Ultrasound scanning has become the gold standard in diagnostic imaging for MPE. Ultrasound can differentiate pleural effusion from lung collapse or pleural thickening.4 USS outperforms CT at identifying pleural features such as: pleural thickness, nodules and adhesions. Features consistent with malignant pleural effusion on USS include: nodules of the pleura or diaphragm, diaphragmatic thickening (>7mm) and pleural thickening (>1cm). These findings on ultrasound have a sensitivity and specificity of differentiating benign from malignant effusions of 79% and 100% respectively. See Figure 2 15 Ultrasound has also developed a key role in pleural procedures. It has the benefit of not exposing the patient to radiation and being able to be performed at the bedside.
Figure 2: Ultrasound: Malignant pleural effusion with diaphragmatic nodules
