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Diagnosis Cancer


Your doctor will start by conducting a physical exam, reviewing your medical history and evaluating your symptoms. The next step will be one of the following tests:

  • Chest X-ray. Most thymomas can be detected in a traditional chest X-ray, but your doctor may order additional imaging tests for more details about the tumor's size, location and composition.
  • Chest CT scan. To take images, a thin X-ray beam rotates around the chest area; then a computer program processes the data to construct a three-dimensional, cross-sectional image.
  • PET scan. This highly sensitive technique uses a radioactive tracer to collect images of body tissues.
  • Chest MRI scan. A powerful magnet linked to a computer is used to create detailed images of structures inside the body.
  • Biopsy. If imaging tests reveal a tumor, your doctor may conduct a biopsy to confirm the diagnosis of thymoma. This involves using a needle or surgical procedure to collect a tissue sample that can be examined in the laboratory.


If the diagnosis is thymoma, your doctor will want to determine the stage or extent of the disease. Staging is a careful process to learn whether cancer has spread and, if so, to which parts of the body. Knowing the stage helps doctors plan treatment. The four stages of thymoma are described below:

  • Stage I. The tumor is confined to the thymus gland.
  • Stage II. Cancer cells have spread to the fat around the thymus or to the lining of the chest cavity.
  • Stage III. Cancer cells have spread to nearby organs, such as the lungs, sac surrounding the heart, or large blood vessels.
  • Stage IV. Cancer cells have metastasized throughout the heart, lungs, blood or lymphatic system.

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.