Disease: Thymoma

    Thymoma facts

    • A thymoma is a type of thymus gland malignancy or cancer. Thymic tumors are uncommon.
    • The thymus gland is present in the front of the space between the lungs called the mediastinum. The thymus gland is most prominent during puberty, but then normally regresses.
    • Thymomas are slightly more common in men than in women and are most frequently seen in persons between the ages of 40 and 60.
    • There are no known risk factors that predispose a person to developing thymoma.
    • Up to half of thymomas are asymptomatic, meaning they do not produce any symptoms or signs and are diagnosed when an imaging study of the chest is performed for another reason.
    • Chest pain, shortness of breath, and cough are common symptoms when symptoms do occur.
    • Many of patients with thymoma will have a so-called paraneoplastic syndrome. A paraneoplastic syndrome occurs preceding or concurrent with the discovery of the underlying cancer. These conditions accompany the cancer’s development but are not a direct result of the disease as might a lump or pain might be. They seem an indirect result of the cancer, and may or may not improve with the treatment of the underlying disease. The most commonly associated condition with thymoma is myasthenia gravis.
    • Thymomas are slow-growing tumors, and the prognosis is excellent when they are discovered in their early stages. 5 year survival for thymoma patients receiving modern treatment approaches 80%. Those with the more rare form of the disease called thymic carcinomas have a more aggressive disease with 5 year survival even with treatment of only about 40% on average.
    • Surgical removal is the mainstay of treatment.

    What is thymoma?

    A thymoma is an uncommon tumor or cancer of the thymus gland. The thymus is a gland located in the anterior mediastinum (the area between the lungs in the chest) that plays a critical role in the development of immune cells during childhood. The thymus gland enlarges during childhood, peaks in size at puberty (about 40 grams) and begins to shrink after an individual reaches puberty.

    Normally, the thymus is made up of a combination of lymphoid cells (immune cells or lymphocytes) and lining cells (epithelial cells). Thymoma is a tumor that originates from the epithelial cells of the thymus. The term thymomic neoplasms is used to refer to tumors of the thymus, which consist of thymomas and thymic carcinomas. Thymic carcinomas are tumors of the thymus having cells with a markedly abnormal appearance under the microscope. Thymic carcinomas are more aggressive than thymomas (they are more malignant), but they account for only about 1% of thymic tumors.

    What causes thymoma, and what are risk factors for thymoma?

    The exact cause of thymomas is not known. Thymomas are slightly more common in men than in women and are most frequently seen in persons between the ages of 40 and 60. There are no known risk factors that predispose a person to developing thymoma.

    What are signs and symptoms of thymoma?

    Up to 50% of thymomas are asymptomatic, meaning they do not produce any symptoms or signs and are diagnosed when an imaging study is performed for another reason. In other cases, the tumor may cause symptoms related to the size of the tumor and the pressure it exerts on adjacent organs. Chest pain, shortness of breath, and cough are common symptoms when symptoms do occur. Fever, night sweats, and weight loss are less common but may occur. Some cases may spread to the lining of the lungs or heart or even to tissues outside the chest. Less than 7% of cases are accompanied by spread outside the chest cavity. Thymic carcinomas are more aggressive tumors than thymomas and are more likely to spread both locally and distantly (metastasize) and to cause symptoms.

    What other medical conditions are associated with thymoma?

    A number of conditions have been associated with thymoma. Medical conditions that are associated with cancers are known as paraneoplastic syndromes, and up to 50% to 60% of patients with thymoma will have one of these related conditions. The most commonly associated condition with thymoma is myasthenia gravis, an autoimmune disease of the nerve-muscle junction that can manifest as weakness, fatigue, double vision, ptosis (drooping eyelid), and problems with swallowing.

    Other associated conditions include other autoimmune diseases including pure red cell aplasia (underdevelopment of precursors for red blood cells in the bone marrow).

    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.

    What causes thymoma, and what are risk factors for thymoma?

    The exact cause of thymomas is not known. Thymomas are slightly more common in men than in women and are most frequently seen in persons between the ages of 40 and 60. There are no known risk factors that predispose a person to developing thymoma.

    What are signs and symptoms of thymoma?

    Up to 50% of thymomas are asymptomatic, meaning they do not produce any symptoms or signs and are diagnosed when an imaging study is performed for another reason. In other cases, the tumor may cause symptoms related to the size of the tumor and the pressure it exerts on adjacent organs. Chest pain, shortness of breath, and cough are common symptoms when symptoms do occur. Fever, night sweats, and weight loss are less common but may occur. Some cases may spread to the lining of the lungs or heart or even to tissues outside the chest. Less than 7% of cases are accompanied by spread outside the chest cavity. Thymic carcinomas are more aggressive tumors than thymomas and are more likely to spread both locally and distantly (metastasize) and to cause symptoms.

    What other medical conditions are associated with thymoma?

    A number of conditions have been associated with thymoma. Medical conditions that are associated with cancers are known as paraneoplastic syndromes, and up to 50% to 60% of patients with thymoma will have one of these related conditions. The most commonly associated condition with thymoma is myasthenia gravis, an autoimmune disease of the nerve-muscle junction that can manifest as weakness, fatigue, double vision, ptosis (drooping eyelid), and problems with swallowing.

    Other associated conditions include other autoimmune diseases including pure red cell aplasia (underdevelopment of precursors for red blood cells in the bone marrow).

    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.

    Source: http://www.rxlist.com

    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.

    Source: http://www.rxlist.com

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