Carcinoma ; classification ; pathology ; Consensus ; Humans ; Thymoma ; classification ; pathology ; Thymus Neoplasms ; classification ; pathology ; World Health Organization

BACKGROUNDThe prognostic relevance of World Health Organization (WHO) subtypes within type B thymomas is still controversial. Understanding of the molecular characteristics of the different histologic types of thymomas will provide meaningful information for diagnosis and therapeutic management in type B thymoma.

METHODSProteins extracted from twelve type B thymoma tissue specimens (six type B1 and six type B2) were analyzed by two-dimensional electrophoresis (2-DE) coupled with MALDI-TOF-MS. Differentially expressed proteins were then assayed in sixty-nine type B thymoma tissues (including B1, B2 and B3) by tissue array analysis with immunohistochemistry staining. The relationship of their expression with clinicopathological parameters, such as tumor stage or WHO classification, was estimated by Spearman's Rank Correlation Test.

RESULTSSixteen differentially expressed proteins between type B1 and B2 thymoma tissues were identified. The differential levels of ezrin and glutathione S-transferase pi (GSTP1) were validated using immunohistochemistry staining. A statistically significant difference was observed in the positive rate of ezrin expression between type B1 thymoma and type B3 thymoma (Z = -2.963, P < 0.01). Ezrin showed a tendency to be expressed in higher classification tumors from type B1 to B3. A statistical analysis demonstrated that type B2 and B3 tumors had significantly higher positive expression of GSTP1 than the B1 group (type B2 vs. B1: Z = -2.582, P = 0.01; type B3 vs. B1: Z = -4.012, P ≤ 0.001). The results also showed a strong correlation between GSTP1 and WHO type staging of B1 to B3 tumors (Spearman's correlation coefficient: 0.633, P ≤ 0.001). Statistical analysis showed that there was close correlation between GSTP1 and ezrin expression with the clinical stage (Spearman's correlation coefficients, ezrin: 0.481, P < 0.05; GSTP1: 0.484, P < 0.01).

CONCLUSIONSDifferentially expressed proteins between type B1 and B2 thymoma tissues were analyzed by comparative proteomic analysis. The techniques of proteomic analysis and tissue array provide a potential tool for screening of key molecules in type B thymoma histological sub-classifications. The statistical analysis of ezrin and GSTP1 expression by immunohistochemistry, especially GSTP1, may be a useful approach for type B thymoma classification.

Adolescent ; Adult ; Aged ; Cytoskeletal Proteins ; metabolism ; Electrophoresis, Gel, Two-Dimensional ; Female ; Glutathione S-Transferase pi ; metabolism ; Humans ; Immunohistochemistry ; Male ; Middle Aged ; Proteome ; metabolism ; Proteomics ; methods ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Thymoma ; classification ; metabolism ; Tissue Array Analysis ; Young Adult

OBJECTIVETo study the correlation between amplification of chromosome 1 and histological typing and clinical staging of thymic epithelial tumors according to the WHO classification.

METHODSAmplification of chromosome 1 was detected by interphase fluorescence in-situ hybridization (FISH) in 60 cases of thymic epithelial tumors, including type A thymoma (2 cases), type AB (19 cases), B1 (4 cases), B2 (14 cases), B3 (11 cases), metaplastic thymoma (2 cases), and thymic carcinoma (8 cases) and 11 samples of normal thymus.

RESULTSGain on chromosome 1 was found in 19 cases (31.7%) of thymic epithelial tumors, and none was detected in normal thymic tissues (P < 0.05). The positive rates of gain on chromosome 1 were statistically different among various histological subtypes of thymic epithelial tumors (P < 0.05), in which the highest rate of detection was in thymic carcinoma (6/8), the second, type B3 (6/11), followed by type A (1/2), type AB (4/19), type B2 (2/14) and type B1 (0). The positive rate of gain on chromosome 1 in type B3 had no statistical difference from thymic carcinoma (P > 0.05), but significantly higher than that in other types of thymoma (P < 0.05). In addition, the polysomy rate of chromosome 1 was significantly different among the thymic epithelial tumors at different clinical stages (P = 0.023), and that at stages III and IV was statistically higher than that in stages I and II (P = 0.003) but there was no significant difference between stage I and stage II tumors (P = 0.750).

CONCLUSIONSGain on chromosome 1 is more common in thymic carcinoma and type B3 thymoma than that in other subtypes of thymic epithelial tumors. Thymoma of type B3 may have different genetic features from other subtypes. Detection of gain on chromosome 1 by FISH is helpful in the differential diagnosis and prediction of prognosis in patients with thymic epithelium tumors.

Adult ; Aged ; Carcinoma, Squamous Cell ; genetics ; pathology ; Chromosomes, Human, Pair 1 ; genetics ; Female ; Follow-Up Studies ; Gene Amplification ; Humans ; Male ; Middle Aged ; Neoplasm Staging ; Polyploidy ; Prognosis ; Thymoma ; classification ; genetics ; pathology ; Thymus Neoplasms ; classification ; genetics ; pathology

OBJECTIVETo study the expression of CD20 in thymomas and its clinical significance.

METHODSOne hundred and seventy-nine cases of thymoma were enrolled into the study. The histologic diagnosis was reviewed by two experienced pathologists on the basis of the 2004 WHO classification. One hundred and two cases were selected for immunohistochemical study for CD20, pancytokeratin, TdT, CD3, CD43, CD99 and S-100 protein. The cases were further categorized into two groups, according to the association with clinical evidence of myasthenia gravis. The immunostaining pattern was then statistically analyzed.

RESULTSAmongst the 102 cases studied, 7 cases belonged to type A thymoma, 32 cases type AB thymoma, 17 cases type B1 thymoma, 15 cases type B2 thymoma, 17 cases type B3 thymoma and 14 cases thymic carcinoma. The expression rates of CD20 in neoplastic epithelial cells of type A, type AB, type B1, type B2 and type B3 thymomas and thymic carcinomas were 3/7, 84.4% (27/32), 1/17, 2/15, 0/17, 0/14, respectively. The proportions of CD20-positive lymphocytes in the background were 3/7, 18.8% (6/32), 14/17, 11/15, 11/17, 6/14, respectively. The proportion of CD20-positive intra-tumoral B lymphocytes in the group of thymomas with myasthenia gravis was 67.5% (22/40), in contrast to 35.5% (22/62) in those without myasthenia gravis.

CONCLUSIONSThe neoplastic epithelial cells in cases of type A and type AB thymoma, as well as few cases of type B1 and B2 thymoma, express CD20. The immunostain highlights the presence of oval, stellate or spindly cells. Thymomas associated with myasthenia gravis contain a significant population of CD20-positive intra-tumoral B lymphocytes. Type AB thymomas may be originated from different populations of cells, rather than a simple admixture of type A and B thymoma cells.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Antigens, CD20 ; metabolism ; B-Lymphocytes ; immunology ; pathology ; Child ; Epithelial Cells ; immunology ; pathology ; Female ; Humans ; Male ; Middle Aged ; Myasthenia Gravis ; complications ; immunology ; pathology ; Thymoma ; classification ; complications ; immunology ; pathology ; Thymus Neoplasms ; classification ; complications ; immunology ; pathology ; Young Adult

OBJECTIVETo study the clinicopathologic characteristics of thymic epithelial tumors and to evaluate the diagnostic reproducibility and clinical relevance of the 2004 WHO histologic classification system.

METHODSThe morphology and immunophenotype of 52 cases of thymic epithelial tumor were reviewed. The tumors were classified according to the new WHO classification system and the clinical data were analyzed.

RESULTSOf the 52 cases studied, 45 were thymomas and 7 were thymic carcinomas. Amongst the 45 cases of thymoma, 6 (13.4%) were type A, 15 (33.3%) were type AB, 4 (8.9%) were type B1, 9 (20.0%) were type B2, 9 (20.0%) were type B3 and 2 (4.4%) were metaplastic thymoma. Amongst the 7 cases of thymic carcinoma, 6 were squamous cell carcinomas and 1 was neuroendocrine carcinoma. The commonest presentations were cough and chest pain. Some cases were incidentally discovered by routine physical examination. Thirteen cases (25.0%) of thymoma were associated with myasthenia gravis. CT scan showed that 49 cases (94.2%) were located in the anterior mediastinum. All cases of type A, AB and B1 thymoma and most cases of B2 thymoma appeared as well-defined homogeneous mass, whereas a few cases of type B2 thymoma and most cases of type B3 thymoma and thymic carcinoma were poorly demarcated and heterogeneous. According to Masaoka staging system, 20 cases (41.7%) belonged to stage I, 15 cases (31.3%) stage II, 11 cases (22.9%) stage III and 2 cases (4.1%) stage IV. The histologic subtypes of thymic epithelial tumors significantly correlated with the clinical stages (chi(2) = 32.5, P < 0.01).

CONCLUSIONSThe 2004 revision of WHO histologic classification system for thymic epithelial tumors shows a high degree of reproducibility. Correlation with the radiologic, clinical and prognostic parameters is helpful in determining the management strategy for individual patients.

Adult ; Aged ; Antibodies, Monoclonal ; analysis ; Antigens, CD20 ; metabolism ; CD5 Antigens ; metabolism ; Carcinoma, Neuroendocrine ; classification ; diagnostic imaging ; metabolism ; pathology ; Carcinoma, Squamous Cell ; classification ; diagnostic imaging ; metabolism ; pathology ; Female ; Follow-Up Studies ; Humans ; Keratins ; immunology ; Male ; Middle Aged ; Myasthenia Gravis ; Neoplasm Recurrence, Local ; Neoplasm Staging ; Prognosis ; Radiotherapy, Adjuvant ; Retrospective Studies ; Thymoma ; classification ; diagnostic imaging ; metabolism ; pathology ; Thymus Neoplasms ; classification ; diagnostic imaging ; metabolism ; pathology ; Tomography, X-Ray Computed

OBJECTIVETo study the prognostic and clinical relevance of histologic subtyping of thymoma according to the World Health Organization (WHO) classification.

METHODSThe clinicopathologic features of 108 patients with thymoma removed surgically were retrospectively reviewed. The histologic diagnosis of the tumors was made on the basis of 2004 WHO classification by two experienced pathologists. The correlation between Masaoka tumor stage, WHO histologic subtype, completeness of resection, presence of myasthenia gravis, other clinical parameters (including age, gender and tumor size) and survival was studied.

RESULTSAccording to WHO classification, there were 7 cases (6.5%) of type A thymoma, 19 cases (17.6%) of type AB thymoma, 23 cases (21.3%) of type B1 thymoma, 19 cases (17.6%) of type B2 thymoma, 27 cases (25.0%) of type B3 thymoma and 13 cases (12.0%) of type C thymoma. According to Masaoka tumor staging, 36 cases (33.3%) were in stage I, 34 cases (31.5%) in stage II, 27 cases (25.0%) in stage III and 11 cases (10.2%) in stage IV(a). The association between histologic subtype and Masaoka tumor stage was statistically significant (P = 0.000). The 5-year survival rates of type A, AB, B1, B2 and B3 thymoma cases were 100%, 100%, 93%, 83% and 43%, respectively; while the 10-year survival rates were 100%, 100%, 81%, 70% and 33%, respectively. The median survival time of type C thymoma was 62.5 months. Type B2 and B3 thymoma cases had an intermediate prognostic ranking in comparison with type C thymoma and other groups (P = 0.000). The 5-year survival rates of tumors in stage I, II and III were 100%, 77% and 54%, respectively; while the 10-year survival rates were 100%, 70% and 27%, respectively. The median survival time of patients in stage IV(a) was 14.0 months. Masaoka tumor stage was highly significant in predicting survival of patients (P = 0.000). On multivariate analysis, Masaoka tumor stage was an independent predictive factor for survival (P = 0.027). On the other hand, the WHO subtype (type A to B1 versus type B2 to B3 versus type C) and completeness of resection could predict the tumor-related survival.

CONCLUSIONSThe Masaoka tumor stage is the single most important prognostic factor of thymoma. The WHO histologic subtype and completeness of resection affect mainly the post-operative survival. The classification of thymoma may also reflect the clinical behavior of the tumor. Type A, AB and B1 thymomas belong to the low-risk group, while type B2 and B3 thymomas have an intermediate prognostic ranking. Type C thymoma carries the worst prognosis.

Adult ; Aged ; Female ; Humans ; Male ; Middle Aged ; Multivariate Analysis ; Myasthenia Gravis ; etiology ; Prognosis ; Survival Analysis ; Thymoma ; classification ; complications ; diagnosis ; pathology ; Thymus Neoplasms ; classification ; complications ; diagnosis ; pathology ; World Health Organization

A thymoma commonly occurs in the superior mediastinum or the upper part of the anterior mediastinum but can be located in other places in rare cases. Cystic degeneration in a thymoma is a relatively common but focal event. In rare cases, the process proceeds to the extent that most if not all of the lesion becomes cystic. We report a case of a patient with a paracardial cystic thymoma in the lower aspect of the anterior mediastinum. A 49-year-old woman was referred to our hospital because of a mass discovered incidentally on a chest X-ray. She showed no symptoms or signs. Contrast-enhanced chest CT scan revealed a 5x5cm sized, well-marginated, right paracardial cystic mass with a curvilinear and oval enhancing solid portion. A Surgical resection was performed. The mass was discontinuous with normal thymic tissue. Microscopy revealed a type B1 thymoma with prominent foci of medullary differentiation according to the WHO classification. There was no capsular or local invasion. The postoperative course was uneventful and the patient was discharged in good health.
Classification ; Female ; Humans ; Mediastinum ; Microscopy ; Middle Aged ; Thorax ; Thymoma* ; Tomography, X-Ray Computed

A thymic carcinoma is a rare malignant neoplasm of the thymus epithelium, which can be distinguished from a benign or invasive thymoma. Contrary to a thymoma, the association of a thymic carcinoma and autoimmune disease is rare, with only a few cases having been reported. Herein, a case of thymic carcinoma diagnosed concurrently with systemic lupus erythematosus (SLE) is reported. A 49 year-old man presented at our clinic with myalgia. He was diagnosed with SLE, based on an oral ulcer, lymphopenia, and positive ANA and anti-Sm antibodies. Incidentally, a routine chest X-ray showed a large mediastinal mass. Pathological examination of the mediastinal mass revealed an undifferentiated thymic carcinoma, of WHO classification type C. Further work-up for staging showed multiple bone and lung metastases. With a palliative aim, he received systemic chemotherapy, but refused further chemotherapy after the 2nd course. Currently, the patient has not been followed up since the chemotherapy.
Antibodies ; Autoimmune Diseases ; Classification ; Drug Therapy ; Epithelium ; Humans ; Lung ; Lupus Erythematosus, Systemic* ; Lymphopenia ; Middle Aged ; Myalgia ; Neoplasm Metastasis ; Oral Ulcer ; Thorax ; Thymoma* ; Thymus Gland

A 65 year-old female was suddenly expired soon after arriving in emergency room. Before arriving, she complained chest discomfort. Her neck mass was diagnosed as thyroid tumor about 11 years ago. She was recommended operation, but not taken due to arrhythmia. The neck mass was originally diagnosed as thyroid mass(goiter) by radiologic studies. The mass (10.5 x 9.5 x 7.0 cm, 319 gm) is mainly located in the lower neck and partly in the anterior superior mediastinum. The trachea is compressed by the mass and its tubal structure is flattened. The cause of death is mechanical asphyxia by thymoma(type B1 according to the WHO classification of thymoma, and stage I according to Masaoka's classification). On review of her past history, paraneoplastic syndrome including myasthenia gravis is not present. Generally, the patient with large thymic mass shows symptoms including chest pain, respiratory difficulty, hemoptysis, cough, superior vena cava syndrome. Although the symptoms related with its mass effect are common, but the death from mechanical asphyxia by thymoma is very rare in recent days.
Aged ; Arrhythmias, Cardiac ; Asphyxia* ; Cause of Death ; Chest Pain ; Classification ; Cough ; Emergency Service, Hospital ; Female ; Hemoptysis ; Humans ; Mediastinum ; Myasthenia Gravis ; Neck ; Paraneoplastic Syndromes ; Superior Vena Cava Syndrome ; Thorax ; Thymoma* ; Thyroid Gland ; Trachea

OBJECTIVETo study the relationship between activation of pro-MMP-2 and expression of matrix metalloproteinases (MMP)-2, MT1-MMP and tissue inhibitor of metalloproteinases (TIMP)-2 mRNA in thymoma and thymic carcinoma; and to study the molecular mechanism of invasion and metastasis of thymic epithelial tumors.

METHODSFresh tissue specimens of thymoma, thymic carcinoma and normal thymus were included. The mRNA expression of MMP-2, MT1-MMP and TIMP-2 were analyzed by real-time reverse transcription polymerase chain reaction. The pro-MMP-2 activation ratio and its localization were determined by gelatin zymography and film in-situ gelatin-Zymography, respectively. Correlation of mRNA expression of MMP-2, MT1-MMP and TIMP-2 was investigated in tumors with different histological subtypes and clinical stages.

RESULTSThere were no significant differences in the expressions of MMP-2, MT1-MMP and TIMP-2 mRNA between I and II stage or III and IV stage thymomas (P > 0.05). However, significant differences of the expressions were observed between three tumor groups: I-II stage, III-IV stage and thymic carcinomas (P < 0.005), and between three histological subtypes: AB-B1 (lymphocyte-rich and mixed types), B2-B3 (cortical and predominantly polygonal cells types) and thymic carcinomas (P < 0.05). Expression levels of MT1-MMP and TIMP-2 mRNA were correlated with pro-MMP-2 activation ratio (Spearman rank correlation: r = 0.7235, r = 0.7647, P < 0.005). The expression of MMP-9 did not show significant differences between thymomas and thymic carcinomas.

CONCLUSIONSMMP-2, MT1-MMP and TIMP-2 mRNA expression levels are correlated with the histologic subtypes and clinical stages of thymoma. The mRNA expressions of MT1-MMP and TIMP-2 are correlated with the activation ratio of pro-MMP-2. It is speculated that upregulation of MT1-MMP gene expression may induce an activation of pro-MMP-2 through TIMP-2.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; enzymology ; metabolism ; pathology ; Enzyme Activation ; Female ; Humans ; Male ; Matrix Metalloproteinase 2 ; biosynthesis ; genetics ; Matrix Metalloproteinases ; biosynthesis ; genetics ; Matrix Metalloproteinases, Membrane-Associated ; Middle Aged ; Neoplasm Staging ; RNA, Messenger ; biosynthesis ; genetics ; Thymoma ; classification ; enzymology ; metabolism ; pathology ; Thymus Gland ; enzymology ; metabolism ; Thymus Neoplasms ; classification ; enzymology ; metabolism ; pathology ; Tissue Inhibitor of Metalloproteinase-2 ; biosynthesis ; genetics