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.
Biomarkers ; Classification ; Epithelial Cells ; Immunohistochemistry ; Thymoma ; Thymus Neoplasms

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

For the purpose of investigating the pattern of E-cadherin (E-CD) expression in thymomas, 72 cases were immunostained using monoclonal antibody (HECD-1) and microwave-enhanced immunohistochemical method on formalin-fixed, paraffin-embedded tissue sections. The thymomas were classified according to modified Muller-Hermelink classification. The spindle-shaped, medullary type tumor epithelial cells in medullary (3 cases) and composite type (20 cases) thymomas rarely expressed E-CD except in focal areas showing microcystic change observed in 8 cases. Meanwhile, the cohesive epithelioid tumor cells in every case of well-differentiated thymic carcinomas (WDTC) (29 cases) expressed E-CD. The epithelial cells in cortical type (13 cases) expressed stronger E-CD compared with those of organoid type (7 cases). In cases of WDTC admixed with cortical type, we observed increasing expression of E-CD as the tumor epithelium forms cohesive sheets. We could not find any loss of E-CD expression in invasive foci of the 11 cases of high-staged WDTC examined. Since the results of our study show a strong correlation between E-CD expression and epithelioid morphology of the tumor, E-CD seems to play a major role as a morpho-regulatory factor rather than as a suppressor of invasion in organotypic thymomas.
Adolescence ; Adult ; Aged ; Cadherins/immunology ; Cadherins/analysis* ; Female ; Human ; Immunohistochemistry ; Male ; Middle Age ; Neoplasm Staging ; Thymoma/pathology ; Thymoma/classification ; Thymoma/chemistry* ; Thymus Neoplasms/pathology ; Thymus Neoplasms/classification ; Thymus Neoplasms/chemistry*

We reviewed 86 thymic epithelial tumors and reclassified them according to the Kirchner and Muller- Hermelink classification. They were subtyped as medullary, mixed, predominantly cortical (organoid), cortical, well differentiated thymic carcinoma, and poorly differentiated thymic carcinoma. The frequency of each subtype was determined and histologic findings were related to stage and myasthenia gravis. Immunohistochemical stains for bcl-2 protein as a marker for medullary thymocytes and MIC-2 protein as a marker for cortical thymocytes were performed in each case. The stages and association of myasthenia gravis was significantly different in each subtypes. The results of this study demonstrate that this histogenetic classification is clinically applicable. The bcl-2 protein was specifically demonstrated in lymphocytes within areas of medullary differentiation and MIC-2 protein in cortical differentiation. The expression of bcl-2 and MIC-2 proteins lend histogenetic support for this new classification of thymoma. Bcl-2 protein is strongly expressed in tumor epithelial cells of every case of poorly differentiated thymic carcinoma whereas the other types of thymic epithelial tumors do not show epithelial expression of this protein. The strong expression of bcl-2 protein in tumor epithelium may be considered as a predictor of aggressive behavior in thymic epithelial tumors.
Classification ; Coloring Agents ; Epithelial Cells ; Epithelium ; Lymphocytes ; Myasthenia Gravis ; Staphylococcal Protein A ; Thymocytes ; Thymoma*

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+/-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 B1, 10 (16.9%) had Type B2 and 7 (11.9%) had Type B3, 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%, B1 and B2 were 70.2%, and B3 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.
Classification* ; Diagnosis ; Female ; Humans ; Male ; Multivariate Analysis ; Myasthenia Gravis ; Neoplasms, Glandular and Epithelial ; Prognosis ; Recurrence ; Thymoma

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

Authors studied 123 patients with myasthia gravis, who were admitted to the Seoul National University Hospital from 1981 to 1986 to get the incidence of thymoma in myasthenia gravis. 1. Among 66 cases, 23 were said to have the thymoma by radiological studies such as chest CT scan. 2. True thymoma were confirmed by histopathologic study in 10 out of 15 cases of CT-made thymoma. 3. The incidence of the associated thymoma in myasthenia gravis was calculated to be 19.2%. 4. Among 10 cases of thymoma, 7 cases were above 40 year of age, 3 cases below 40. 5. When these were classified by modified Osserman's classification, type IIA was numbered in only one, type IIB in 5, type III in 2, and type IV in 2. Therefore it is concluded that the thymoma plays significant role in myasthenia gravis and it is important to manage it in the diagnosis and treatment of myasthenia gravis.
Classification ; Diagnosis ; Humans ; Incidence ; Myasthenia Gravis ; Seoul ; Thymoma* ; Tomography, X-Ray Computed

Carcinoma, Neuroendocrine ; pathology ; Carcinoma, Squamous Cell ; pathology ; Humans ; Neoplasm Staging ; Thymoma ; classification ; pathology ; Thymus Neoplasms ; classification ; pathology ; World Health Organization

A clinical study was performed on 27 patients with myasthenia gravis diagnosed at the Department of Ophthalmology, St. Mary's Hospital, Catholic University Medical College from January 1986 to December 1989, including electromyography, chest CT scan and thyroid function test. The results were as follow: 1. The patients were classified as group I;14 patients(51.9%), most common, group II(A);8 patients(29.6%) and group II(B);5 patients(18.5%) based on the modified Osserman's classification. 2. Ocular symptoms were ptosis in 25 patients(92.6%), diplopia in 10 patients(34. 4%), limitation of ocular movement in 4 patients(14.8%). Systemic symptoms were dysphagia and weakness of extremeties in 6 patients(22.2%) and general weakness in 5 patients(18. 5%). 3. In EMG study, among the 27 patients, 17 patients(63%) revealed positive response. Positive rate according to clinical classification was 50%(7 of 14 patients) in group 1,62.5%(5 of 8 patients) in group II(A) and 100%(all 5 patients) in group II(B). The more severe the symptoms, the more positive were the findings. 4. The associated thymic disorders were thymoma in 4 patients(14. 8%), thymic hyperplasia in 2 patients(6.9%) and malignant thymoma in 1 patient(6.9%).
Classification ; Deglutition Disorders ; Diplopia ; Electromyography* ; Humans ; Myasthenia Gravis* ; Ophthalmology ; Thymoma ; Thymus Hyperplasia ; Thyroid Function Tests ; Tomography, X-Ray Computed

The authors experienced 21 myasthenia gravis patients who were admitted to Kyung Hee University Hospital and Han Yang University Hospital from March 1979 to August 1983. Following results were obtained through treatment and follow up evaluation. 1. There was no sexual difference between male and female, of 21 patients male to female ratio was 10:11. The prevalent age group was 20s and 30s. (10 of 21 patients, 47.6%). 2. The most common initial symptom was ptosis (71.4%), followed by diplopia (38.0%), generalized muscle weakness (38.0%), swallowing difficulty(19.0%), Mastication difficulty (9.5%), dysarthria (4.8%), respiratory difficulty (4.8%), in order. 3. Among 21 patients, thymomas were found in 2 patients. (9.5%) 4. According to the modified Osserman's classification, the peak incidence group was IIA (7 cases, 33.3%) then IIB (5 cases, 23.8%). Group III and neonatal type were not seen. 5. In 14 patients (66.6%), diagnosis was made within 1 year after the onset of the symptoms, but the other 7 patients (33.3%) spent more than 1 year for the diagnosis. 6. All patients who received corticosteroid therapy or thymectormy were improved significantly after the treatment. 7. After the discharge, 3 patients (14.3%) make normal life, on the other hand 17 patients (80.9%) are in more or less restricted life.
Classification ; Deglutition ; Diagnosis ; Diplopia ; Dysarthria ; Female ; Follow-Up Studies ; Hand ; Humans ; Incidence ; Male ; Mastication ; Muscle Weakness ; Myasthenia Gravis* ; Thymoma