Thymomas account for the vast majority of thymic neoplasms and are often associated with autoimmune or neurological syndromes, most commonly myasthenia gravis.
About one third of thymomas are asymptomatic and identified as an incidental radiographic finding. A chest CT with intravenous contrast is usually diagnostic.
Small, encapsulated tumours are resected for both pathological diagnosis and treatment. For anterior mediastinal tumours with a substantial chance of representing lymphoma, core needle biopsy is recommended. Thymic malignancies that are locally advanced at presentation are usually treated with induction therapy (chemotherapy ± radiotherapy) followed by reassessment for surgery. Patients with myasthenia gravis should have myasthenic symptoms optimised before surgery.
Thymomas are relatively indolent tumours with high cure rates; however, all thymomas are considered malignant. Prognosis depends largely on completeness of resection, stage (Masaoka-Koga staging system and more recent 8th edition of the American Joint Committee on Cancer TNM staging system), and WHO histology. Thymic carcinomas and neuroendocrine tumours of the thymus (NETT) are generally more aggressive.
Treatment for locally advanced and metastatic tumours should involve a multidisciplinary team of medical oncologists, thoracic surgeons, radiation oncologists, pathologists, and radiologists who have experience and expertise in thymic malignancies.
Thymic tumours are rare, although they are the most common anterior mediastinal tumours in adults. Thymomas account for the majority of thymic neoplasms. Although smaller tumours are typically asymptomatic and identified incidentally on imaging (unless associated with myasthenia gravis), large tumours can present with chest discomfort, cough, and/or dyspnoea, with or without myasthenia gravis symptoms. About one third of thymomas are diagnosed as an incidental finding.
History and exam
Key diagnostic factors
- myasthenia gravis
- muscle weakness
- facial and upper extremity oedema
- facial plethora
- distended veins in the neck, chest, and/or abdominal wall
- left-arm swelling
Other diagnostic factors
- fever and/or weight loss
- history of myasthenia gravis
- age >45 years
1st investigations to order
- chest x-ray
- chest CT with intravenous contrast medium
Investigations to consider
- chest MRI
- tissue biopsy
- acetylcholine receptor antibodies
- PET/CT scan
locally advanced tumour
Douglas Z. Liou, MD
Clinical Assistant Professor of Cardiothoracic Surgery
Division of Thoracic Surgery
Stanford University School of Medicine
DZL declares that he has no competing interests.
Joseph B. Shrager, MD
Professor of Cardiothoracic Surgery
Chief, Division of Thoracic Surgery
Medical Director, Thoracic Oncology CCP
Stanford University School of Medicine / Stanford Cancer Institute
JBS declares that he has no competing interests.
Dr Douglas Z. Liou and Dr Joseph B. Shrager would like to gratefully acknowledge Dr Tracey Evans, Dr Nicholas Choong, Dr Mario Gasparri, and Dr Cameron Wright, previous contributors to this topic.
TE has received consultancy fees from Genentech and Celgene. She is a board member of Wissahickon Hospice. Educational events include an annual thoracic educational series sponsored by Imedex. NC and MG declare that they have no competing interests. CW is an author of a number of references cited in this topic.
Kenneth Kesler, MD
Professor of Surgery
Division of Cardiothoracic Surgery
Department of Surgery
Indiana University School of Medicine
KK declares that he has no competing interests.
James Huang, MD
Assistant Attending Surgeon
Memorial Sloan-Kettering Cancer Center
JH is an author of a number of references cited in this topic.
Enrico Ruffini, MD
University of Torino
ER is an author of a reference cited in this topic.
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