• Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

How is thymoma diagnosed?

If a thymoma is not causing symptoms, it is sometimes identified incidentally, meaning it is found on an imaging test of the chest (for example, X-ray, computerized tomography or CT scan) that is performed for another reason. If symptoms are present, chest X-rays or other imaging studies, such as CT scans or magnetic resonance imaging (MRI) scans or the combination of PET and CT scans, are typically carried out to identify the source of the symptoms. While a mass in the anterior mediastinum can be seen on imaging studies, the definitive diagnosis can only be established when the mass is either removed surgically and examined by a pathologist or when a biopsy (surgical removal of a small portion of tissue for diagnostic purposes) is taken. Such biopsies are only done in locally advanced cases which are not likely resectable for cure. The biopsy should not be done through, or violate, the pleural space around the lung. Microscopic examination of the tumor tissue is necessary to confirm the diagnosis of thymoma or thymic carcinoma.

What are the stages of thymoma?

The stage of a tumor refers to the extent to which it has spread to other local organs and tissues or to distant sites throughout the body. There are two commonly used staging systems for thymoma, both of which classify the tumors as Stage 1 through Stage 4, depending upon the extent of spread and the degree of tissue invasion. While there are some differences in the two methods used to stage thymomas, a Stage 1 tumor represents an encapsulated tumor (surrounded by a capsular structure) that has not spread outside of the thymus gland. Stage 4 represents the opposite extreme, in which invasion and spread to distant organs has occurred. The tissue itself is classified A, B, or C based on its characteristics. Type C thymoma is thymic carcinoma, and is quite rare.

What is the treatment for thymoma?

The treatment for thymoma is primarily surgical removal. The success of surgical treatment depends upon the particular characteristics of the tumor and its precise location; tumors that can be completely removed have a higher surgical cure rate. If all evidence of disease is unable to be removed and microscopic, or gross or macroscopic tumor remains after surgery, then radiation therapy and chemotherapy have been used as an adjunct to surgical resection. Chemotherapy is generally used for metastatic thymoma and thymoma that cannot be grossly surgically removed.

Medically Reviewed by a Doctor on 3/16/2016

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