From the Guidelines
Mast cells can cause pleural effusions in patients by releasing inflammatory chemicals that disrupt the normal fluid balance in the pleural space, and treatment should focus on controlling the underlying mast cell disorder with medications like antihistamines and mast cell stabilizers, as well as thoracentesis for immediate relief. When mast cells accumulate abnormally in conditions like mastocytosis or mast cell activation syndrome, they release substances like histamine, cytokines, and proteases, which increase blood vessel permeability, allowing fluid to leak into the pleural space (the area between the lungs and chest wall) 1. Additionally, mast cell mediators can trigger inflammation of the pleural membranes, further contributing to fluid accumulation. The inflammatory process can also block lymphatic drainage, which normally removes excess fluid from the pleural space. In some cases, mast cell disorders may cause pleural effusions indirectly by affecting other organs like the heart or liver, which can lead to fluid imbalances throughout the body.
Some key points to consider in the management of pleural effusions caused by mast cell disorders include:
- The use of antihistamines, such as H1 and H2 blockers, to reduce the frequency and severity of mast cell activation symptoms 1
- The use of mast cell stabilizers, such as cromolyn sodium, to prevent mast cell degranulation and reduce inflammation
- The potential use of tyrosine kinase inhibitors, such as imatinib, in severe cases of mast cell disorders
- The importance of thoracentesis, or draining fluid from the pleural space, for immediate relief of symptoms
- The need for long-term management of the underlying mast cell disorder to prevent recurrence of pleural effusions.
It's also important to note that the management of pleural effusions should be guided by the underlying cause of the effusion, and that a systematic approach to investigation is necessary to establish a diagnosis and guide treatment 1. This may include the use of thoracic ultrasound, CT scans, and other diagnostic tests to evaluate the size and character of the effusion, as well as the presence of any underlying conditions that may be contributing to the development of the effusion.
From the Research
Mast Cell Role in Pleural Effusions
- Mast cells (MCs) have been identified as key players in the formation of malignant pleural effusions (MPEs) 2
- MCs are attracted to the pleural space by tumors that elaborate CCL2 and osteopontin, leading to degranulation and release of tryptase AB1 and IL-1β 2
- The release of these mediators induces pleural vasculature leakiness and triggers NF-κB activation in pleural tumor cells, fostering pleural fluid accumulation and tumor growth 2
Mechanisms of Mast Cell-Mediated Pleural Effusion
- MCs release histamine and other pro-inflammatory mediators, which can increase vascular permeability and contribute to fluid accumulation in the pleural space 3, 4
- The stabilization of MCs by agents such as cromolyn sodium can reduce the release of these mediators and potentially limit pleural effusion formation 3, 4
Clinical Implications
- The presence of MCs in pleural effusions can be a diagnostic marker for malignant pleural effusions 2
- Targeting MCs with therapies such as c-KIT inhibitors may be a potential treatment strategy for MPEs 2
- Further research is needed to fully understand the role of MCs in pleural effusion formation and to develop effective therapeutic approaches 5, 6