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Case History

Image not available. A 55-year-old man complains of aching central chest pain, slowly progressive over the past 6 months. There are no abnormal findings on examination. A chest radiograph and a computed tomography (CT) scan reveal an anterior mediastinal mass with extension of the tumour around the pleura and pericardium. A biopsy confirms a thymoma.

What is the stage of the thymoma?

What is the place of surgical resection?

In the presence of residual or recurrent disease what are the treatment options?

What is the patient's prognosis?

Background

What is the stage of the thymoma?

Image not available. Thymomas are a rare form of cancer, accounting for 0.2–1.5% of all malignancies. However, they represent the most common tumours of the anterior mediastinum, where most thymomas (90%) occur. The rest arise in the neck or other areas of the mediastinum. They are indolent tumours, and are typically discovered as an incidental finding on chest radiograph. Of those patients with symptoms, 40% have local symptoms of chest pain, cough, or dyspnoea related to tumour compression or invasion, and 30% present with systemic symptoms. Parathymic syndromes, in particular myasthenia gravis, hypogammaglobulinaemia and pure red cell aplasia, may develop.

Although thymomas are often encapsulated and non-invasive at the time of presentation, approximately 50% of tumours invade through their own capsules, extending into surrounding structures. Transdiaphragmatic extension into the abdomen and metastasis into the ipsilateral pleura and pericardium can occur. Rarely, there is haematogenous/lymphogenous spread with metastases to the liver and bone.

The most widely used staging system for thymomas is the system proposed by Masaoka et al. in 1981.1 Based on the extent of either microscopic or macroscopic invasion into mediastinal structures, patients can be grouped into four main stages (Table 48.1).

Table 48.1Thymoma staging system of Masaoka

At presentation, approximately 40% of thymomas are stage I, 25% each are stage II or III, 10% are stage IVA and only 1% or 2% are stage IVB.2 This patient presents with a classic history of slow-onset chest pain and the finding of pleural and pericardial involvement on CT scan makes this stage IVA disease.

What is the place of surgical resection?

Surgery is the treatment of choice for localized thymomas. Patients with stage I disease who undergo a complete resection have 5-year survival rates of over 90%. In patients with more advanced disease, radical surgery aimed at complete resection should also be ...

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