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==Epidemiology and Demographics==
 
==Epidemiology and Demographics==
The prevalence of thymic carcinoma is approximately 0.00006 per 100,000 individuals worldwide. Males are more commonly affected with thymic carcinoma than females. The male to female ratio is approximately 3 to 1. Thymic carcinoma usually affects African American and Asian individuals. Caucasian individuals are less likely to develop thymic carcinoma.  
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The prevalence of thymic carcinoma is approximately 0.00006 per 100,000 individuals worldwide. Males are more commonly affected with thymic carcinoma than females. The male to female ratio is approximately 3 to 1. It is more common in Asians and African Americans than in Caucasians. Thymic malignancies are relatively rare in the range of 0.2% to 1.5% of all malignancies or 0.13 per 100,000 person-years in the United States. Thymic malignancies are among the most common mediastinal primary tumors with up to 50% of anterior mediastinal masses proving to be of thymic descent. Invasive thymomas and thymic carcinomas are relatively rare tumors, which together represent about 0.2% to 1.5% of all malignancies. Thymic carcinoma are rare and have been reported to account for only 0.06% of all thymic neoplasms. The risk of thymic carcinoma increases with age. Thymic carcinoma is uncommon in children, it is seen more often in middle-aged adults. Thymic carcinoma commonly affects individuals between 40-60 years of age.
  
 
==Risk Factors==
 
==Risk Factors==
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==Natural History, Complications and Prognosis==
 
==Natural History, Complications and Prognosis==
Thymic carcinomas are generally considered indolent tumors due to long recurrence intervals (median of 68 months). The most common sites of distant recurrence are [[lung]], [[liver]], [[bone]], [[kidney]], [[brain]], and [[bone marrow]].<ref name="www.ncbi.nlm.nih.gov">{{Cite web  | last =  | first =  |title = Recurrence of thymoma: clinicopathological feat... [J Surg Oncol. 2001] - PubMed - NCBI | url = http://www.ncbi.nlm.nih.gov/pubmed/11745803 | publisher =  | date =  | accessdate = }}</ref> The most important factor for prognosis is the stage and grade of the thymic carcinoma. The 5-year and 10-year overall survival rates in patients with thymic carcinoma are 38% and 28% respectively.<ref name="Ogawa-2002">{{Cite journal  | last1 = Ogawa | first1 = K. | last2 = Toita | first2 = T. | last3 = Uno | first3 = T. | last4 = Fuwa | first4 = N. | last5 = Kakinohana | first5 = Y. | last6 = Kamata | first6 = M. | last7 = Koja | first7 = K. | last8 = Kinjo | first8 = T. | last9 = Adachi | first9 = G. | title = Treatment and prognosis of thymic carcinoma: a retrospective analysis of 40 cases. | journal = Cancer | volume = 94 | issue = 12 | pages = 3115-9 | month = Jun | year = 2002 | doi = 10.1002/cncr.10588 | PMID = 12115342 }}</ref> The subtypes squamous cell carcinoma, mucoepidermoid carcinoma, and basaloid carcinoma have a better prognosis than other histological subtypes.
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Thymic carcinomas are generally considered indolent tumors due to long recurrence intervals (median of 68 months). The most common sites of distant recurrence are lung, liver, bone, kidney, brain, and bone marrow.The most important factor for prognosis is the stage and grade of the thymic carcinoma. The 5-year and 10-year overall survival rates in patients with thymic carcinoma are 38% and 28%, respectively.[2] The subtypes squamous cell carcinoma, mucoepidermoid carcinoma, and basaloid carcinoma have a better prognosis than other histological subtypes. There are no reported cases of complications regarding the carcinoma by itself. Most complications occur during surgery and biopsy. The most important factor for prognosis is the stage and grade of the thymic carcinoma. The 5-year and 10-year overall survival rates in patients with thymic carcinoma are 38% and 28% respectively.
  
 
==Diagnosis==
 
==Diagnosis==
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===CT===
 
===CT===
Chest CT scan may be helpful in the diagnosis of thymic carcinoma. On CT scan of the chest, thymic carcinoma is characterized by lobulated mass with irregular borders, heterogeneous attenuation, and mediastinal fat invasion with areas of necrosis, haemorrhage, calcification, or cyst formation.
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 +
Chest CT scan may be helpful in the diagnosis of thymic carcinoma. On CT scan of the chest, thymic carcinoma is characterized by lobulated mass with irregular borders, heterogeneous attenuation and mediastinal fat invasion with areas of necrosis, haemorrhage, calcification, or cyst formation.Large and highly aggressive anterior mediastinal mass. Areas of necrosis, haemorrhage, calcification, or cyst formation Aross invasion of contiguous mediastinal structures and wide spread to involve distant intrathoracic sites. High incidence of extrathoracic metastases Lobulated mass with irregular borders, heterogeneous attenuation, and mediastinal fat invasion. Pleural and pericardial effusion might also be seen on CT. Thymic carcinoma is singnificantly larger than thymoma on chest CT scan.
  
 
===MRI===
 
===MRI===

Latest revision as of 03:43, 10 November 2019

Thymic Carcinoma Microchapters

Home

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Thymic carcinoma from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

Staging

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

Chest X Ray

Echocardiograph and Ultrasound

CT

MRI

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Marjan Khan M.B.B.S.[2]

Overview

Thymic carcinoma, also known as type C thymoma, is a rare condition (less than 0.13/100,000/year) but should be included in the differential diagnosis of anterior mediastinic masses. It is a tumor of the thymic epithelium, like thymoma, but it is associated with lack of immature lymphocytes and often presents with more invasive or metastatic disease. Thymic carcinomas can metastasize, generally to pleura, kidney, bone, liver, or brain. The thymic carcinoma is a tumor of the thymic epithelium, but it is associated with lack of immature lymphocytes and often presents with more invasive or metastatic disease.[1] The pathophysiology of thymic carcinoma depends on the histological subtype. On microscopic histopathological analysis, thymic carcinoma is divided into squamous cell carcinoma, basaloid carcinoma, mucoepidermoid carcinoma, lymphoepithelioma-like carcinoma, sarcomatoid carcinoma (carcinosarcoma), clear cell carcinoma, papillary adenocarcinoma, carcinoma with t(15;19) translocation, neuroendrocrine carcinomas, undifferentiated carcinoma, and combined thymic epithelial tumors.[2] Thymic carcinoma has not been reported in association with myasthenia gravis, in contrast with thymoma.[3] The cause of thymic carcinoma has not been identified. The most common differential diagnosis of thymic carcinoma is thymoma, which is the most common pathology of the thymus. Thymic carcinoma must be differentiated from other mediastinal masses such as germ cell tumors, lymphoma, thyroid tumors, and metastatic carcinoma to the mediastinal lymph nodes.[4] The prevalence of thymic carcinoma is approximately 0.00006 per 100,000 individuals worldwide. Males are more commonly affected with thymic carcinoma than females. The male to female ratio is approximately 3 to 1. It is more common in Asians and African Americans than in Caucasians. There are no established risk factors for thymic carcinoma.[5] Thymic carcinomas are generally considered indolent tumors due to the long recurrence intervals (median of 68 months). The most common sites of distant recurrence are lung, liver, bone, kidney, brain and bone marrow.[6] The most important factor for prognosis is the stage and grade of the thymic carcinoma. The 5-year and 10-year overall survival rates in patients with thymic carcinoma are 38% and 28% respectively.[7] The subtypes squamous cell carcinoma, mucoepidermoid carcinoma, and basaloid carcinoma have a better prognosis than other histological subtypes. The staging of thymic carcinoma is based on the Masoka and GETT staging system.[8] Symptoms of thymic carcinoma include dull chest pain, cough, dyspnea, and constitutional symptoms. Chest CT scan may be helpful in the diagnosis of thymic carcinoma. On CT scan of the chest, thymic carcinoma is characterized by lobulated mass with irregular borders, heterogeneous attenuation, and mediastinal fat invasion with areas of necrosis, hemorrhage, calcification, or cyst formation. Chest MRI scan may be diagnostic of thymic carcinoma. Findings on chest MRI suggestive of thymic carcinoma include isointense to slightly hyperintense signal compared to muscle on T1 weighted image and heterogeneous signal on T2 weighted image. On T1 weighted image with gadolinium contrast, linear regions of enhancement may be observed coursing through the mass, which are thought to represent fibrous septae.[9] Other imaging studies for the diagnosis of thymic carcinoma include FDG PET scan. The standarized uptake value (SUV) in the FDG PET is much higher for the thymic carcinoma than thymoma, with a high sensitivity (84.6%) and specificity (92.3%).[10][11] Other diagnostic studies for thymic carcinoma include immunohistochemistry. The predominant therapy for thymic carcinoma is surgical resection. Adjunctive cisplatin-basedchemotherapy may be required.[12] Surgery is the mainstay of treatment for thymic carcinoma.[12] There is no established method for primary prevention of thymic carcinoma. There are no secondary preventive measures available for thymic carcinoma.

Historical Perspective

The thymic epithelial tumor staging system was initially proposed by Bergh and his colleagues in 1978, modified by Wilkins and Castleman in 1979, and further developed by Masaoka et al. in 1981.

Classification

Thymic carcinomas may be classified according to a histological grading system into either low grade subtypes or high grade subtypes.[1]. Primary thymic carcinomas are rare malignant neoplasms of the mediastinum, and combined thymic carcinomas are even less common. Although tumor stage is the single most important prognostic factor in thymoma, a combination of stage and histologic subtype should be considered in predicting survival.

Pathophysiology

The thymic carcinoma is a tumor of the thymic epithelium, but it is associated with a lack of immature lymphocytes and often presents with a more invasive or metastatic disease.The pathophysiology of thymic carcinoma depends on the histological subtype. On microscopic histopathological analysis, thymic carcinoma is divided into squamous cell carcinoma, basaloid carcinoma, mucoepidermoid carcinoma, lymphoepithelioma-like carcinoma, sarcomatoid carcinoma (carcinosarcoma), clear cell carcinoma, papillary adenocarcinoma, carcinoma with t(15;19) translocation, neuroendrocrine carcinomas, undifferentiated carcinoma, and combined thymic epithelial tumors. Thymic carcinoma has not been reported in association with myasthenia gravis, in contrast with thymoma

Causes

The cause of thymic carcinoma has not been identified.

Differentiating Thymic carcinoma from other Diseases

The most common differential diagnosis of thymic carcinoma is thymoma, which is the most common pathology of the thymus. Thymic carcinoma must be differentiated from other mediastinal masses such as germ cell tumors, lymphoma, thyroid tumors, and metastatic carcinoma to mediastinal lymph nodes.[4]

Epidemiology and Demographics

The prevalence of thymic carcinoma is approximately 0.00006 per 100,000 individuals worldwide. Males are more commonly affected with thymic carcinoma than females. The male to female ratio is approximately 3 to 1. It is more common in Asians and African Americans than in Caucasians. Thymic malignancies are relatively rare in the range of 0.2% to 1.5% of all malignancies or 0.13 per 100,000 person-years in the United States. Thymic malignancies are among the most common mediastinal primary tumors with up to 50% of anterior mediastinal masses proving to be of thymic descent. Invasive thymomas and thymic carcinomas are relatively rare tumors, which together represent about 0.2% to 1.5% of all malignancies. Thymic carcinoma are rare and have been reported to account for only 0.06% of all thymic neoplasms. The risk of thymic carcinoma increases with age. Thymic carcinoma is uncommon in children, it is seen more often in middle-aged adults. Thymic carcinoma commonly affects individuals between 40-60 years of age.

Risk Factors

There are no established risk factors for thymic carcinoma.[5]

Natural History, Complications and Prognosis

Thymic carcinomas are generally considered indolent tumors due to long recurrence intervals (median of 68 months). The most common sites of distant recurrence are lung, liver, bone, kidney, brain, and bone marrow.The most important factor for prognosis is the stage and grade of the thymic carcinoma. The 5-year and 10-year overall survival rates in patients with thymic carcinoma are 38% and 28%, respectively.[2] The subtypes squamous cell carcinoma, mucoepidermoid carcinoma, and basaloid carcinoma have a better prognosis than other histological subtypes. There are no reported cases of complications regarding the carcinoma by itself. Most complications occur during surgery and biopsy. The most important factor for prognosis is the stage and grade of the thymic carcinoma. The 5-year and 10-year overall survival rates in patients with thymic carcinoma are 38% and 28% respectively.

Diagnosis

Staging

The staging of thymic carcinoma is based on the Masoka and GETT staging system.[8]

History and Symptoms

Symptoms of thymic carcinoma include dull chest pain, cough, dyspnea, and constitutional symptoms.

Physical Examination

The physical examination plays a limited role in the diagnosis of thymic carcinoma.

Laboratory Findings

There are no diagnostic lab findings associated with thymic carcinoma.

Chest X Ray

Chest x ray may be helpful in the diagnosis of thymic carcinoma.

CT

Chest CT scan may be helpful in the diagnosis of thymic carcinoma. On CT scan of the chest, thymic carcinoma is characterized by lobulated mass with irregular borders, heterogeneous attenuation and mediastinal fat invasion with areas of necrosis, haemorrhage, calcification, or cyst formation.Large and highly aggressive anterior mediastinal mass. Areas of necrosis, haemorrhage, calcification, or cyst formation Aross invasion of contiguous mediastinal structures and wide spread to involve distant intrathoracic sites. High incidence of extrathoracic metastases Lobulated mass with irregular borders, heterogeneous attenuation, and mediastinal fat invasion. Pleural and pericardial effusion might also be seen on CT. Thymic carcinoma is singnificantly larger than thymoma on chest CT scan.

MRI

Chest MRI scan may be diagnostic of thymic carcinoma. Findings on chest MRI suggestive of thymic carcinoma include isointense to slightly hyperintense signal compared to muscle on T1 weighted image and heterogeneous signal on T2 weighted image. On T1 weighted image with godalinum contrast, linear regions of enhancement may be observed coursing through the mass, which are thought to represent fibrous septae.[9]

Other Imaging Findings

Other imaging studies for thymic carcinoma include FDG PET scan. The standarized uptake value (SUV) in the FDG PET is much higher for the thymic carcinoma than thymoma, with a high sensitivity (84.6%) and specificity (92.3%).[10][11]

Other Diagnostic Studies

Other diagnostic studies for thymic carcinoma include immunohistochemistry.

Medical Therapy

The predominant therapy for thymic carcinoma is surgical resection. Adjunctive cisplatin-basedchemotherapy may be required.[12]

Surgery

Surgery is the mainstay of treatment for thymic carcinoma.[12]

Primary Prevention

There is no established method for prevention of thymic carcinoma.

Secondary Prevention

There are no secondary preventive measures available for thymic carcinoma.

References

  1. Thomas CR, Wright CD, Loehrer PJ (1999). "Thymoma: state of the art". Journal of Clinical Oncology : Official Journal of the American Society of Clinical Oncology. 17 (7): 2280–9. PMID 10561285. Retrieved 2012-01-18. Unknown parameter |month= ignored (help)
  2. Suster, S.; Rosai, J. (1991). "Thymic carcinoma. A clinicopathologic study of 60 cases". Cancer. 67 (4): 1025–32. PMID 1991250. Unknown parameter |month= ignored (help)
  3. Harris, C.C (2004), Pathology and Genetics of Tumours of the Lung, Pleura, Thymus and Heart (PDF), Lyon: IARC, retrieved 01/03/2016 Check date values in: |accessdate= (help)
  4. 4.0 4.1 Travis WD, Organization WH, Cancer IA et al. Pathology and Genetics of Tumours of the Lung, Pleura, Thymus and Heart. Diamond Pocket Books (P) Ltd.; 2004.
  5. 5.0 5.1 Engels, EA. (2010). "Epidemiology of thymoma and associated malignancies". J Thorac Oncol. 5 (10 Suppl 4): S260–5. doi:10.1097/JTO.0b013e3181f1f62d. PMID 20859116. Unknown parameter |month= ignored (help)
  6. "Recurrence of thymoma: clinicopathological feat... [J Surg Oncol. 2001] - PubMed - NCBI".
  7. Ogawa, K.; Toita, T.; Uno, T.; Fuwa, N.; Kakinohana, Y.; Kamata, M.; Koja, K.; Kinjo, T.; Adachi, G. (2002). "Treatment and prognosis of thymic carcinoma: a retrospective analysis of 40 cases". Cancer. 94 (12): 3115–9. doi:10.1002/cncr.10588. PMID 12115342. Unknown parameter |month= ignored (help)
  8. 8.0 8.1 Masaoka A, Yamakawa Y, Niwa H, Fukai I, Saito Y, Tokudome S; et al. (1994). "Thymectomy and malignancy". Eur J Cardiothorac Surg. 8 (5): 251–3. PMID 8043287.
  9. 9.0 9.1 Thymic epithelial tumours. Radiopaedia. http://radiopaedia.org/articles/thymic-epithelial-tumours. Accessed on 3rd January 2016.
  10. 10.0 10.1 "The Thymus: A Comprehensive Review1" (2006). RadioGraphics 26 (2): 335–348. doi:10.1148/rg.262045213. ISSN 0271-5333. 
  11. 11.0 11.1 Thymic Carcinoma. Radiopaedia. http://radiopaedia.org/articles/thymic-carcinoma. Accessed on 3rd January 2016.
  12. 12.0 12.1 12.2 12.3 National Cancer Institute. General Information About Thymoma and Thymic Carcinoma Treatment. http://www.cancer.gov/types/thymoma/hp/thymoma-treatment-pdq. Accessed on 22nd December, 2015.

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