From the Guidelines
The workup for a mediastinal mass should begin with a thorough history and physical examination, followed by chest imaging with a contrast-enhanced CT scan of the chest, as it provides better characterization of the mass compared to chest X-ray alone 1. The initial imaging approach may also include MRI chest without and with intravenous contrast, which is equivalent to CT chest with IV contrast in terms of providing the necessary clinical information for effective patient management 1. Laboratory tests should include complete blood count, comprehensive metabolic panel, lactate dehydrogenase (LDH), and tumor markers relevant to suspected pathologies. Additional imaging may include PET-CT to assess metabolic activity and potential metastases, although its value is limited beyond conventional CT in the initial assessment of mediastinal masses, except in cases of primary mediastinal lymphoma staging and surveillance 1. Tissue diagnosis is essential and can be obtained through CT-guided needle biopsy, endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), mediastinoscopy, or video-assisted thoracoscopic surgery (VATS) depending on the location and characteristics of the mass. Some key points to consider in the diagnostic approach include:
- For anterior mediastinal masses, evaluating for myasthenia gravis with acetylcholine receptor antibodies if thymoma is suspected.
- For middle mediastinal masses, bronchoscopy may be helpful if there is airway involvement.
- The choice of diagnostic approach depends on the location of the mass, suspected diagnosis based on imaging characteristics, patient's clinical presentation, and local expertise.
- Multidisciplinary discussion involving thoracic surgery, pulmonology, and oncology is recommended to determine the optimal diagnostic and treatment strategy.
- Image-guided transthoracic needle biopsy, including CT-guided and MR-guided biopsies, has been shown to be safe and effective in diagnosing mediastinal masses, with core biopsy being more effective than fine-needle aspiration 1.
From the Research
Mediastinal Mass Workup
- The evaluation of a mediastinal mass begins with a history and physical examination to discover evidence of compression or obstruction to any of the mediastinal organs 2.
- The most efficient radiographic approach after a plain chest roentgenogram is computed tomography (CT) of the thorax, supplemented as needed by selected plain tomograms or a barium swallow examination 2.
- Radiological compartmentalisation of the mediastinum helps in focusing the diagnosis of masses on the basis of their site 3.
- The location and composition of the lesions, as well as the degree of vascularisation and relationships with mediastinal structures assessed by CT or magnetic resonance imaging (MRI), are critical to narrowing the differential diagnosis 3.
Imaging Modalities
- CT and MRI are important for the diagnosis of mediastinal masses 3.
- Special applications at MRI have been developed to identify accurately the tissue components of the mediastinal masses 3.
- The likelihood of malignancy of the mediastinal masses is influenced by the symptomatology and the age of the patient 3.
Diagnostic Approach
- A structured approach for radiologists and clinicians is presented to facilitate the evaluation of patients with anterior mediastinal tumors 4, 5.
- Attention to age and gender, combined with identification of certain radiographic and clinical characteristics, allows a presumptive diagnosis to be established in most patients 5.
- Discussion with the clinician can be very helpful in formulating a presumptive diagnosis 4.
- Confirmatory imaging or biopsy tests are most beneficial in particular situations 4.