Tumours of the Mediastinum
Frequency, compartmental distribution, clinical features, and the key biopsy decision in anterior mediastinal masses.
Overview
Mediastinal tumours encompass a wide spectrum of pathology. The frequency distribution and compartmental location of these tumours provides a powerful diagnostic framework before tissue is obtained.
Anterosuperior compartment tumours are more often malignant, especially in patients aged 10–40 years. In children, neurogenic tumours and lymphomas are the most common subtypes. Absence of symptoms is a reasonably good indicator of benignity — two-thirds of symptomatic patients have malignant disease.
Tumours by compartment
| Compartment | Tumour types |
|---|---|
| Prevascular (anterior) | Thymic lesions (cysts, hyperplasia, thymoma, thymic carcinoma, thymic carcinoid) · Germ cell tumours · Lymphoma · Intrathoracic goitre · Metastatic lymphadenopathy |
| Visceral (middle) | Foregut cysts · Bronchogenic cysts · Lymphoma · Metastatic lymphadenopathy · Tracheal lesions |
| Paravertebral (posterior) | Neurogenic tumours · Spine infections (discitis, osteomyelitis) · Cold abscess · Haematoma |
Clinical features
About one-third of patients with mediastinal masses are asymptomatic — discovered incidentally on chest imaging. Two-thirds present with non-specific symptoms: cough, dyspnoea, chest pain, heaviness, or fever. Features pointing to malignancy include mechanical compression or invasion of mediastinal structures.
| Structure compressed / invaded | Symptoms and signs |
|---|---|
| SVC | SVC syndrome — facial oedema, arm swelling, dilated neck veins, headache; worse on leaning forward |
| Trachea / bronchi | Stridor, wheeze, dyspnoea, cough, atelectasis |
| Oesophagus | Dysphagia, regurgitation |
| Recurrent laryngeal nerve | Hoarseness, bovine cough |
| Phrenic nerve | Ipsilateral diaphragmatic palsy — dyspnoea, raised hemidiaphragm |
| Sympathetic chain | Horner's syndrome — ptosis, miosis, anhidrosis |
| Brachial plexus | Arm pain, weakness (T1 distribution) |
Investigations
- Chest X-ray: localises the mass; calcification common in intrathoracic goitre and teratoma; lateral view essential to assign compartment
- CT chest: investigation of choice — characterises size, density (fat, calcification, cystic components), relationship to adjacent structures, pleural and pericardial involvement
- MRI: superior to CT for vascular invasion, neural foraminal involvement, and cardiac invasion
- Echocardiography: for visceral compartment tumours to assess cardiac and pericardial involvement
- PET-CT: distinguishes high-grade from low-grade thymic lesions; useful for lymphoma staging
- Tumour markers: AFP and β-hCG in all young patients (rule out GCT); LDH for lymphoma
- CT-guided core biopsy: tissue diagnosis in 80–90% of cases
- Mediastinoscopy / mediastinotomy: when CT-guided biopsy fails or anatomical access is limited
In a young patient with an anterior mediastinal mass — always obtain AFP and β-hCG before biopsy. If a GCT is likely, tissue is required. If a thymoma appears encapsulated and resectable on CT, biopsy before surgery risks capsule breach and tumour seeding — proceed directly to resection. If lymphoma is suspected clinically, CT-guided core biopsy or excision of a peripheral lymph node is preferred over mediastinoscopy.
Mediastinal cysts
Primary cysts account for approximately 20% of mediastinal masses. Types include bronchogenic cysts (most common — 50–60%; paratracheal or carinal location; lined by respiratory epithelium), pericardial cysts (right cardiophrenic angle; typically asymptomatic), oesophageal duplication cysts (posterior mediastinum; can cause dysphagia), and neuroenteric cysts (associated with vertebral anomalies). All symptomatic cysts should be excised — VATS is preferred for accessible lesions. Asymptomatic cysts may be monitored but carry risk of infection, haemorrhage, or rupture.
All clinical content should be verified against current guidelines before clinical application. This resource is intended for revision and educational purposes only.
Standard textbooks
- Shields TW, LoCicero J, Reed CE, Feins RH. General Thoracic Surgery. 7th ed. Lippincott Williams & Wilkins.
- Sellke FW, del Nido PJ, Swanson SJ. Sabiston & Spencer Surgery of the Chest. 9th ed. Elsevier.
- Pearson FG, et al. Thoracic Surgery. 3rd ed. Churchill Livingstone.