• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5581-5585
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• 2012

Objective: To explore the relationship between computed tomography (CT) manifestations of thymoma and its WHO pathological classification. Methods: One hundred and five histopathologically confirmed cases were collected for their pathological and CT characteristics and results were statistically compared between different pathological types of thymoma. Results: Tumor size, shape, necrosis or cystic change, capsule integrity, invasion to the adjacent tissue, lymphadenopathy, and the presence of pleural effusion were significantly different between different pathological types of thymomas (P<0.05). Type B2, B3 tumors and thymic carcinomas were greater in size than other types. More than 50% of type B3 tumors and thymic carcinomas had a tumor size greater than 10 cm. The shape of types A, AB, and B1 tumors were mostly round or oval, whereas 75% of type B3 tumors and 85% of thymic carcinomas were irregular in shape. Necrosis or cystic change occurred in 67% of type B3 thymomas and 57% of thymic carcinomas, respectively. The respective figures for capsule destruction were 83% and 100%. Increases in the degree of malignancy were associated with increases in the incidence of surrounding tissue invasion: 33%, 75%, and 81% in type B2, type B3, and thymic carcinomas, respectively. Pleural effusion occurred in 48% of thymic carcinomas, while calcification was observed mostly in type B thymomas. Conclusions: Different pathological types of thymic epithelial tumors have different CT manifestations. Distinctive CT features of thymomas may reflect their pathological types.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2745-2748
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• 2012

Aims: To study KIT (CD117) expression in thymic epithelial tumors in China, and investigate diagnostic and clinical significance. Material and Methods: Thymic epithelial tumors (TETs) from 102 patients (3 type A, 29 type AB, 5 type B1, 22 type B2, 29 typeB3 and 16 thymic carcinomas) were examined. Immunohistochemical staining with an antic-kit monoclonal antibody was performed on a tissue microarray. Relationships between KIT positive expression and the TET clinical characteristics (WHO histologic classification and Masaoka stage system) were analysed. Results: The KIT positive expression rate was significantly higher in thymic carcinoma (60%, 9/16) than in thymoma (8%, 7/86), a strong correlation being found with the WHO classification, but not the Masaoka tumor stage. The overall survival for patients with KIT positive lesions was significantly worse. Conclusions: KIT is a good molecule marker to differentially diagnose thymic carcinoma from thymoma, while also serving as a predictor of prognosis for TETs. Further research into KIT mutations in Chinese TETs should be conducted to assess the efficacy of targeted therapy.

• Journal of Chest Surgery
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• v.37 no.8
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• pp.684-690
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• 2004

Background: Primary thymic epithelial neoplasm is a type of mediastinal tumors that have various biologic and morphologic features. In this study, we reclassified 59 cases of thymic epithelial tumors by the new WHO classification. We inquired whether the new WHO classification has independent prognostic relevance by analyzing clinical characteristics of thymic epithelial tumors including Masaoka's clinical stage. Material and Method: From December 1986 to August 2003, 59. patients who underwent surgery in the Keimyung University Dongsan Medical Center with definite diagnosis of thymic epithelial tumor were studied. We analyzed the histologic subtype (WHO classification). clinical stage (Masaoka's clinical stage) and patient's characteristics (sex, age, myasthenia gravis, tumor size, invasion. recurrence, metastasis) as prognostic factors. We analyzed the relationship between histologic subtype and clinical stage. Result: 32 patients were male and 27 were female. Mean age was 50.1$\pm$14.2. From WHO A to C, all thymic epithelial tumors were reclassified by the new WHO classification. Six patients (10.2%) had Type A, 7 (11.9%) had Type AB, 7 (11.9%) had Type B$_1$, 10 (16.9%) had Type B$_2$ and 7 (11.9%) had Type B$_3$, 22 (37.3%) had Type C. Two factors were shown by multivariate analysis to be associated with a favorable prognosis: completeness of resection (p=0.003) and non-invasiveness (p=0.001). The overall 5-year survival of the 59 patients was 53%, subtype A and AB were 92.3%, B$_1$ and B$_2$ were 70.2%, and B$_3$ and C were 26.1%. The association between histologic subtype and invasive behavior (stage) was statistically significant (p<0.001). Conclusion: The WHO classfication is not only a histologic classfication of the thymic epithelial tumors but also a significant prognostic factor that influence the survival of thymic epithelial tumors.

• Tuberculosis and Respiratory Diseases
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• v.65 no.1
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• pp.23-28
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• 2008

Background: Thymic epithelial tumors are the most common tumors affecting the anterior mediastinum. The aim of this study is to investigate clinical features of the patients who were diagnosed with thymic epithelial tumors at Pusan National University Hospital. Methods: We retrospectively reviewed the records of thirty-seven patients who were diagnosed with thymic epithelial tumors from Jan. 1997 to Jan. 2007. The pathological classification and clinical stage of the thymic epithelial tumors were based on the WHO classification and Masaoka's staging system. A total 37 patients were enrolled: 23 were males and 14 were females, and their mean age was 51.3 years. Results: Thirty patients presented symptoms at the time of diagnosis and their symptoms were as follows: chest pain (53%), dyspnea (23%), and cough (17%). Myasthenia gravis was diagnosed in five patients. With respect to the tumor staging, three cases (8%) were stage I, 10 cases (28%) were stage II, 12 cases (32%) were stage III, 6 cases (16%) were stage IVA and 6 cases (16%) were stage IVB. Twenty-four cases (67%) displayed stage III or IV disease. The pathological types according to the WHO classification were as follows: B1 (32%), C (23%), B3 (20%), B2 (16%), AB (6%) and A (3%). Twenty-four patients underwent thymothymectomy and four of these patients relapsed. Stage III or type B3 was common in the relapsed patients. Five patientsexpired. Stage IV or type B3 and C were common in the expired patients. Conclusion: In this study, stage III or IV disease and type B3 or C were common at the time of diagnosis and these findings might contribute to postoperative recurrence and a poor outcome.

• Journal of Yeungnam Medical Science
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• v.27 no.2
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• pp.98-104
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• 2010

Primary anterior mediastinal neoplasms comprise a diverse group of tumors and account for 50% of all mediastinal masses. Thymic epithelial neoplasm are most common and classified into thymoma, invasive thymoma, and thymic carcinoma. Neuroendocrine differentiation of thymic epithelial neoplasm are rare malignancies. Germ cell tumor (GCT) is second most common anterior mediastinal tumor and most of them are mature cystic teratoma. Malignant mediastinal GCT are rare than benign. Primary thoracic lymphoma is rare than thoracic involvement of systemic lymphoma and most common location of primary thoracic lymphoma is anterior mediastinum. The clinical and radiologic appearance of the most common masses are reviewed.

• Tuberculosis and Respiratory Diseases
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• v.46 no.5
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• pp.718-722
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• 1999

Thymoma is the most common tumor in the compartment of anterior mediastinum. The malignant thymoma is classified into invasive thymoma(category I) and thymic carcinoma(category II). Recently, well-differentiated thymic carcinoma is a proposed category 1.5 used to describe a subset of thymic epithelial tumors, allowing for the existence of intermediate form based on the clinical features and the histological characteristics. Thymic cyst is a congenital or a acquired disorder. Congenital thymic cyst may develop due to failure of the thymopharyngeal duct to obliterate and acquired thymic cyst develops from inflammation(multilocular thymic cyst), or neoplasm(cystic thymoma). Cystic degeneration in thymoma is a relatively frequent but focal event. In rare cases, the process proceeds to the extent that most or all of the lesion becomes cystic. Until now, well-differentiated thymic carcinoma with extensive cystic degeneration has not been reported in our country. We experienced a case of 14 year-old female patient showing extensive cystic degeneration in well-differentiated thymic carcinoma. And so we report it with review of the articles related.

• Journal of Chest Surgery
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• v.32 no.8
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• pp.726-731
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• 1999

Background: The distinction between non-invasive and invasive or thymic carcinoma has been severely compromised by lack of objective morphological criteria. A reliable biological marker of tumor aggressiveness is, therefore, mandatory for predicting tumor behavior. Material and Method: Thirty thymic epithelial tumors, including 7 non-invasive thymoma, 10 invasive thymoma, and 13 thymic carcinoma of the Rosai's classification; and 5 stage I, 7 stage II, 2 stage III, and 3 stage IVa of the Masaoka stage of thymoma were investigated for expression of bcl-2 and p53 proteins by immunohistochemistry. Result: The thymic epithelial cells showed positive immunostain for bcl-2 in 0 (0%), 3 (30%), 8 (61.5%) of categories in the Rosai's classification respectively and in 0 (0%), 1 (14.3%), 2 (100%), 0 (0%) of stage I, II, III, IVa of the Masaoka stage respectively. Thymic carcinoma, and high stage thymoma had significantly higher proportion of bcl-2 expression than thymoma (p=0.021) and low stage thymoma (p=0.011). However, p53 showed no correlation with the histological subtypes nor with clinical aggressiveness. Bcl-2 expression appeared to be positively correlated with p53 immunoactivity (p=0.007, kappa=0.525). Conclusion: These date indicate that bcl-2 expression correlates with aggressiveness in thymic epithelial tumors, but further studies on mutation of p53 protein is necessary because bcl-2 expression appeared to be positively correlated with p53 immunoactivity.

• Korean Journal of Radiology
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• v.20 no.4
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• pp.671-682
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• 2019

Objective: To investigate whether computed tomography (CT) and fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) may be applied to distinguish thymic epithelial tumors (TETs) from benign cysts in the anterior mediastinum. Materials and Methods: We included 262 consecutive patients with pathologically proven TETs and benign cysts 5 cm or smaller who underwent preoperative CT scans. In addition to conventional morphological and ancillary CT findings, the relationship between the lesion and the adjacent mediastinal pleura was evaluated qualitatively and quantitatively. Mean lesion attenuation was measured on CT images. The maximum standardized uptake value (SUVmax) was obtained with FDG-PET scans in 40 patients. CT predictors for TETs were identified with multivariate logistic regression analysis. For validation, we assessed the diagnostic accuracy and inter-observer agreement between four radiologists in a size-matched set of 24 cysts and 24 TETs using a receiver operating characteristic curve before and after being informed of the study findings. Results: The multivariate analysis showed that post-contrast attenuation of 60 Hounsfield unit or higher (odds ratio [OR], 12.734; 95% confidence interval [CI], 2.506-64.705; p = 0.002) and the presence of protrusion from the mediastinal pleura (OR, 9.855; 95% CI, 1.749-55.535; p = 0.009) were the strongest CT predictors for TETs. SUVmax was significantly higher in TETs than in cysts (5.3 ± 2.4 vs. 1.1 ± 0.3; p < 0.001). After being informed of the study findings, the readers' area under the curve improved from 0.872-0.955 to 0.949-0.999 (p = 0.066-0.149). Inter-observer kappa values for protrusion were 0.630-0.941. Conclusion: Post-contrast CT attenuation, protrusion from the mediastinal pleura, and SUVmax were useful imaging features for distinguishing TETs from cysts in the anterior mediastinum.

• Journal of Chest Surgery
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• v.55 no.2
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• pp.126-142
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• 2022

Background: Thymic epithelial tumors (TETs) are rare, and information regarding their surgical outcomes and prognostic factors has rapidly changed in the past few decades. We analyzed surgical treatment practices for TETs and outcomes in terms of overall survival (OS) and freedom from recurrence (FFR) during a 13-year period in Korea. Methods: In total, 1,298 patients with surgically resected TETs between 2000 and 2013 were enrolled retrospectively. OS and FFR were calculated using the Kaplan-Meier method and evaluated with the log-rank test. Prognostic factors for OS and FFR were analyzed with multivariable Cox regression. Results: A total of 1,098 patients were diagnosed with thymoma, and 200 patients were diagnosed with thymic carcinoma. Over the study period, the total number of patients with surgically treated TETs and the proportion of patients who underwent minimally invasive thymic surgery (MITS) increased annually. The 5-year and 10-year survival rates of surgically treated TETs were 91.0% and 82.1%, respectively. The 5-year and 10-year recurrence rates were 86.3% and 80.0%, respectively. The outcomes of surgically treated TETs improved over time. Multivariable Cox hazards analysis for OS, age, tumor size, and Masaoka-Koga stage were independent predictors of prognosis. The World Health Organization classification and tumor-node-metastasis (TNM) staging were also related to the prognosis of TETs. Conclusion: Surgical treatment of TETs achieved a good prognosis with a recent increase in MITS. The M-K stage was the most important prognostic factor for OS and FFR. The new TNM stage could also be an effective predictor of the outcomes of TETs.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.715-719
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• 1990

Thymoma is defined as a neoplasm of the epithelialreticular framework cells of the thymus. The treatment of choice and the prognosis for patients with thymoma are still controversial subjects due to lack of a uniform histological classification and standardized criteria for typing thymic tumors. Between June 1985 and May 1989, eight patients underwent thymomectomy at the Department of Thoracic and Cardiovascular Surgery, Korea University Medical Center. A clinical analysis was performed and the following result was obtained. In histologic cell type, epithelial type was 2 cases, lymphocytic type 3 cases, and mixed type was 3 cases. The clinical stage was classified by Masaoka’s classification that Stage I was 4 cases, Stage II; 2 cases, Stage III; 2 cases and Stage IV was none. Myasthenia Gravis was associated with thymoma in 5 patients. In 8 patients, thymomectomy were performed. Adjuvant radiotherapy was performed in one patient with Stage I due to suspicious tumor remnant and in Stage II, III patients routinely. Combined chemotherapy was performed in one patient with Stage III due to local recurrence. We concluded that the most important prognostic factor of thymoma is extent of tumor invasion. And the presence of Myasthenia Gravis is no more prognostic factor. Surgical resection of thymoma is treatment of choice, If local invasion or distant dissemination is present, postoperative radiotherapy and /or combined chemotherapy is recommended.