Thymoma and thymic carcinoma originate within the epithelial cells of the thymus, resulting in an anterior mediastinal mass. The term thymoma is customarily used to describe neoplasms that show no overt atypia of the epithelial component.[
Thymic carcinoma or type C thymoma is a thymic epithelial tumor that exhibits clear-cut cytological atypia and histological features no longer specific to the thymus. Thymic carcinomas have a higher incidence of capsular invasion and metastases.[
Other tumors that involve the thymus gland include lymphomas, germ cell tumors, carcinomas, and carcinoids. Hodgkin lymphoma and non-Hodgkin lymphoma may also involve the thymus and must be differentiated from true thymomas and thymic carcinomas.
References:
Incidence
Primary tumors of the thymus are exceptionally rare in children, and very few pediatric studies have been reported.[
Clinical Presentation
Childhood thymomas are usually located in the anterior mediastinum and discovered during a routine chest x-ray. Symptoms may include the following:[
About 40% of adults with thymomas have one or more paraneoplastic disorders during their lifetime.[
Various other paraneoplastic syndromes have been found to be associated with thymomas. These include pure red cell aplasia, hypogammaglobulinemia, nephrotic syndrome, and autoimmune or immune disorders such as scleroderma, dermatomyositis, systemic lupus erythematosus, rheumatoid arthritis, and thyroiditis. Endocrine disorders associated with thymomas include hyperthyroidism, Addison disease, and panhypopituitarism.[
Prognosis
The following studies have reported the outcomes of patients with thymomas:
Treatment of Childhood Thymoma
Treatment options for childhood thymoma include the following:
Surgery
Surgery is the mainstay of therapy, and an attempt should be made to resect all disease.[
Radiation therapy
Thymoma is relatively radiosensitive, and radiation therapy is used for patients with unresectable or incompletely resected invasive disease.[
Chemotherapy
Chemotherapy is usually reserved for patients with advanced-stage disease who have not responded to radiation therapy or corticosteroids. Agents that have been effective include doxorubicin, cyclophosphamide, etoposide, cisplatin, ifosfamide, and vincristine.[
Octreotide
Because thymoma shows high uptake of indium In 111–labeled octreotide, trials using this somatostatin analogue have been conducted in patients with refractory disease. In an Eastern Cooperative Oncology Group phase II trial of 42 patients, 4 patients had partial responses to octreotide alone, and 8 patients responded with the addition of prednisone to octreotide.[
Sunitinib
In an open-label phase II study of sunitinib in adult patients with refractory thymomas, partial responses were observed in 6% of patients, and stable disease was achieved in 75% of patients.[
For more information about the treatment of thymomas, see
Treatment Options Under Clinical Evaluation for Childhood Thymoma
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the
References:
Incidence and Prognosis
The European Cooperative Study Group for Pediatric Rare Tumors identified 20 patients with thymic carcinomas between 2000 and 2012.[
Treatment of Childhood Thymic Carcinoma
Treatment options for childhood thymic carcinoma include the following:
Surgery
Surgery is the mainstay of therapy, and an attempt should be made to resect all disease.[
Radiation therapy
Thymic carcinoma is relatively radiosensitive, and radiation therapy is used for patients with unresectable or incompletely resected invasive disease.[
Chemotherapy
Response rates are lower for patients with thymic carcinomas who receive chemotherapy, but 2-year survival rates have been as high as 50%.[
For more information, see the
Sunitinib
In an open-label phase II study of sunitinib in adult patients with refractory thymic carcinomas, partial responses were observed in 26% of patients, and stable disease was achieved in 65% of patients.[
For more information about the treatment of thymic carcinomas in adults, see
Treatment Options Under Clinical Evaluation for Childhood Thymic Carcinoma
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the
References:
Cancer in children and adolescents is rare, although the overall incidence has slowly increased since 1975.[
For specific information about supportive care for children and adolescents with cancer, see the summaries on
The American Academy of Pediatrics has outlined guidelines for pediatric cancer centers and their role in the treatment of children and adolescents with cancer.[
Dramatic improvements in survival have been achieved for children and adolescents with cancer. Between 1975 and 2020, childhood cancer mortality decreased by more than 50%.[
Childhood cancer is a rare disease, with about 15,000 cases diagnosed annually in the United States in individuals younger than 20 years.[
The designation of a rare tumor is not uniform among pediatric and adult groups. In adults, rare cancers are defined as those with an annual incidence of fewer than six cases per 100,000 people. They account for up to 24% of all cancers diagnosed in the European Union and about 20% of all cancers diagnosed in the United States.[
Most cancers in subgroup XI are either melanomas or thyroid cancers, with other cancer types accounting for only 2% of the cancers diagnosed in children aged 0 to 14 years and 9.3% of the cancers diagnosed in adolescents aged 15 to 19 years.
These rare cancers are extremely challenging to study because of the relatively few patients with any individual diagnosis, the predominance of rare cancers in the adolescent population, and the small number of clinical trials for adolescents with rare cancers.
Information about these tumors may also be found in sources relevant to adults with cancer, such as
References:
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
This summary was comprehensively reviewed.
This summary is written and maintained by the
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of childhood thymoma and thymic carcinoma. It is intended as a resource to inform and assist clinicians in the care of their patients. It does not provide formal guidelines or recommendations for making health care decisions.
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This summary is reviewed regularly and updated as necessary by the
Board members review recently published articles each month to determine whether an article should:
Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.
The lead reviewers for Childhood Thymoma and Thymic Carcinoma Treatment are:
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Levels of Evidence
Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Pediatric Treatment Editorial Board uses a
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The preferred citation for this PDQ summary is:
PDQ® Pediatric Treatment Editorial Board. PDQ Childhood Thymoma and Thymic Carcinoma Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at:
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Last Revised: 2024-09-12
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