Thymoma and thymic carcinoma

Cancer affecting the thymus gland is rare and the cause is unknown. This information is about thymoma and thymic carcinoma. However, other cancers can affect the thymus gland, such as lymphomas, germ cell tumours and neuroendocrine tumours.

Thymomas are rare. The most common age for people to be diagnosed with a thymoma is between 40 and 60 years. Thymomas tend to be benign (non-cancerous) and slow-growing but some can spread, mainly within the chest.

Thymic carcinoma is even rarer and can affect people of any age. It's malignant (cancerous), fast-growing and may spread to other parts of the body.

Associated conditions

Because the thymus gland is involved in the development of the immune system, some people with a thymus gland tumour will also have immune system-related illnesses.

One of these is a condition called myasthenia gravis. The main symptom of this is that muscles become tired and easily weakened.

As many as 4 out of every 10 people (40%) with a thymoma will also have myasthenia gravis. Thymic carcinoma is less commonly associated with myasthenia gravis.

Another associated condition is a type of anaemia called pure red cell aplasia. Anaemia means that there aren't enough red blood cells to carry oxygen around the body. It causes tiredness and sometimes breathlessness. Pure red cell aplasia affects about 1 out of every 20 people (5%) who have a thymus gland tumour.

Other conditions that may be associated with a thymus gland tumour include immune diseases of the nervous system or bowel, such as ulcerative colitis or Crohn's disease.

Symptoms of thymoma and thymic carcinoma

Symptoms of a thymus gland tumour include:

  • chest pain
  • a persistent cough
  • shortness of breath
  • difficulty swallowing
  • hoarseness of the voice
  • swelling of the neck due to the tumour pressing on blood vessels in the chest - this is called superior vena cava obstruction (SVCO) .

It is possible for a thymus gland tumour to be found following a chest x-ray for something else, even if the person has no symptoms.

Finding that a person has an autoimmune system disease such as myasthenia gravis may lead a doctor to suspect and carry out tests for a thymus gland tumour.

Some people with a later stage disease may have reduced immunity and so be more likely to develop infection.

*Information provided by Macmillan cancer support

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