Thymoma arising in a thymic cyst.

We present a case of thymoma arising in the wall of the thymic cyst. A 77-year-old asymptomatic woman demonstrated an approximately 3.5 cm sized cystic mass in the left anterior mediastinum in the CT scan. The tumor was extirpated by a total thymectomy. Histologically, the cyst wall was lined by low cuboidal cells, but a markedly thickened wall was observed at the upper site of the mass, which was found to be thymoma. These findings may suggest that the thymoma originated from the wall of the thymic cyst.     

A surgically treated case of capsulated thymoma with thymic cyst

A 56-year-old woman was pointed out an abnormal shadow on chest roentgenogram. Chest CT and MRI showed a solid mass with a cyst at right anterior mediastinum. Clinical diagnosis was thymoma with cyst, and surgical excision was performed. The histopathological examination of the resected specimen demonstrated that the epithelia of the cyst wall was single cuboidal or squamous cells and contained some foci of thymic tissue. The solid mass was capsulated and predominantly composed of lymphocytes. The pathological diagnosis was a thymoma (predominantly lymphocytic type) with thymic cyst. She is doing well for 10 years postoperatively.     

Thymoma within a giant congenital thymic cyst

Congenital thymic cysts are very rare and mostly asymptomatic mediastinal lesions. Thymoma within such cysts is even more uncommon and has so far hardly been described. We report on a 41-year-old male with a World Health Organization type B1 thymoma within the wall of a huge unilocular thymic cyst. Because of the possible coexistence of typical congenital thymic cyst and thymoma, we recommend surgical resection both for establishing the diagnosis and for definite treatment.     

Microthymoma and microscopic thymomas associated with a thymic cyst without solid component

A 75-year-old asymptomatic man presented with an anterior mediastinal cyst without a solid component on computed tomography. Pathologic examination of the specimens obtained by thoracoscopic resection showed a thymic cyst with a 1.6-mm type A microthymoma in the surrounding thymic tissue. In addition, there were multiple hyperplastic nodules smaller than 1 mm histologically corresponded to microscopic thymomas. The patient underwent completion thymectomy through median sternotomy; thereafter, there was no residual thymic neoplasm detected. This was the first case report of a type A microthymoma. Microthymoma or microscopic thymoma could be present concomitantly with a thymic cyst without a solid component.     

Invasive thymoma with thymic cyst; report of a case

A 27-year-old woman was pointed out an abnormal shadow on chest X-ray in 1999. Because of the enlargement of the chest abnormal shadow, she was admitted to our hospital in 2000. Chest computed tomography (CT) revealed anterior mediastinal solid mass with cystic lesion. A thymoma was suspected. The tumor was removed in June 2000, through a longitudinal incision of the sternum. There was a severe adhesion between the tumor and the right brachiocephalic vein. Histological examination revealed a thymoma with thymic cyst. The thymoma had a capsular invasion (stage II). There were few reports for cases of thymoma with thymic cyst.     

Rapid enlargement of a mediastinal mass: thymoma hemorrhage into a thymic cyst

A 52-year-old man was admitted to Matsudo City Hospital because of an anterior mediastinal mass. One month prior, when he suddenly suffered chest pain, computed tomography (CT) showed a 4 x 3 cm mass in the chest. On admission, the symptom disappeared. However, chest CT revealed rapid enlargement of the mass to 10 x 6 cm. Based on the CT findings, we suspected a tumor. Therefore, we performed a thymothymectomy. The mass, measuring 12 x 8 x 6 cm, contained a solid tumor and a fl uid-filled cyst. Pathology showed a thymoma and a multilocular thymic cyst. We speculated that hemorrhage from the thymoma spread into the multilocular thymic cyst and enlarged the mass.     

经颈部切口全胸腺切除术13例

目的探讨经颈部切口的全胸腺切除术治疗前纵隔胸腺内小病灶的临床应用价值。方法2007年3月～2011年12月行经颈部切口全胸腺切除术13例,使用常规手术器械及头灯照明,经颈横切口从胸骨后间隙完整游离肿瘤及全胸腺并切除。结果1例因游离中发现侵犯左无名静脉中转胸骨正中切口切除肿瘤。12例经颈部切口全胸腺切除术平均手术时间48．1min（38—60min）,平均术中出血量45ml（30～50m1）,平均术后住院3．7d（2～7d）。1例术后第2天出现房颤,药物治疗后转窦性心率。13例均无手术相关性死亡。术后病理：MasaokaI期胸腺瘤2例,Ⅱ期胸腺瘤3例,Ⅲ期胸腺瘤1例,胸腺增生3例,胸腺脂肪瘤、胸腺囊肿、异位甲状旁腺囊肿、巨大淋巴结增生各1例。5例MasaokaI／Ⅱ期胸腺瘤术后均未行放化疗,随访3～57个月均存活,未见肿瘤复发;1例MasaokaⅢ期胸腺瘤术后放疗50Gy,随访14个月,无复发;胸腺增生3例术后症状均明显改善,随访14～28个月均完全缓解;其余4例良性胸腺肿瘤随访31—59个月,均存活,未见肿瘤复发。结论经颈部切口的全胸腺切除术治疗前纵隔胸腺内早期小病灶是安全可行的。对于合并胸腺内病变的早期重症肌无力患者及≤5cm的MasaokaI／Ⅱ期胸腺瘤患者的手术确切疗效有待于进一步病例数的积累。     

Thymoma with intracystic dissemination arising in a unilocular thymic cyst

A 33-year-old asymptomatic woman was referred to our hospital for evaluation of an abnormal shadow on a chest radiograph. A chest-computed tomogram revealed a cystic, partially solid tumor in the right inferior mediastinum. Following an initial diagnosis of cystic teratoma, surgery was performed. The tumor, a well-encapsulated, thin-walled cyst located within the right inferior lobe of the thymus, was extirpated by partial resection of the thymus. The cut surface revealed a unilocular cyst containing multiple grayish-white tumors on the inner cyst walls. Some tumors detached from the wall owing to loose connections. Microscopic findings revealed that the cyst was lined with squamous epithelium. The tumor on the cyst wall was diagnosed to be a type B1 thymoma. Based on these findings, we diagnosed this case as a thymoma originating from the wall of a thymic cyst, accompanied by intracystic dissemination from the tumor.     

Infrasternal mediastinoscopic surgery for anterior mediastinal masses

Background Infrasternal mediastinoscopic surgery is a new alternative to the thoracoscopic approach for patients with anterior mediastinal masses.Methods We applied this technique to 18 thymectomies, one thymomectomy, and one cystectomy in a total of 20 patients with anterior mediastinal masses and then assessed the surgical results.Results Infrasternal mediastinoscopic surgery was accomplished in 18 of the 20 patients (90%). The pathological diagnoses included 13 Masaoka stage I thymomas, one stage II thymoma, two stage III thymomas, one thymic cyst, one pericardial cyst, one thymic granuloma, and one mature teratoma. Two patients with stage III thymoma required conversion to sternotomy, one for invasion into the innominate vein and the other for invasion into the pericardium. There was no surgically related mortality or complications in any patients.Conclusion Infrasternal mediastinoscopic surgery is safe and feasible for stage I thymoma and other benign tumors in the anterior mediastinum.     

Cystic thymoma without solid mass lesions on diagnostic imaging —A case report—

A 68-year-old man was referred to our hospital because of an abnormal shadow on a chest X-ray film. A chest CT scan snd MRI demonstrated a cystic mass without solid lesions on the anterior mediastinum. The CT scan also showed that it was a well-defined and homogenous mass without contrast enhancement effect. ⁶⁷Ga and ²⁰¹T1 scintigrams showed no uptake in the mass. Needle aspiration cytology was performed, and there was no evidence of neoplasms. A thymic cyst was diagnosed, and then an operation was performed. At the operation, the cystic tumor was removed along with thymic tissues by a median sternotomy. On the cut section of the resected specimen, the tumor was found to be a cyst with small solid nodules on the wall. Pathologic examination revealed that the tumor was a cystic thymoma. We consider that patients with cystic tumors on the onterior mediastinum should obtain histopathologic diagnosis because of the difficulty in excluding neoplasms such as thymoma.     

Adenocarcinoma of the thymus: report of two cases,including a previously undescribed mucinous subtype

We report two cases of primary thymic adenocarcinoma, a very uncommon neoplasm with limited information in the literature. Both patients were men (age 15 and 39 years). The first case was a mucinous carcinoma, a subtype of adenocarcinoma not previously recognized in the thymus. It comprised islands and strips of mucin-rich tumor cells floating in large pools of extracellular mucin. There was transition of carcinomatous epithelium to the attenuated epithelium of a thymic cyst. Immunostaining for high molecular weight cytokeratin furthermore highlighted in one area negatively stained tumor islands wrapped by positively stained residual thymic medullary epithelium, suggesting in situ origin of the carcinoma from the thymic epithelium. The second case was a papillary carcinoma with high nuclear grade and many psammoma bodies. It showed strong immunoreactivity for CD5 and did not stain for CA-125 as well as thyroid, pulmonary, and mesothelial markers. The findings in this study therefore broaden the morphologic spectrum of thymic adenocarcinomas to include a mucinous subtype. Review of the literature indicates that thymic adenocarcinomas usually arise from thymic cyst or type A thymoma, and the clinical outcome is variable.     

Regression of thymoma associated with a multilocular thymic cyst: report of a case

A 28-year-old male was diagnosed with acute pericarditis after presenting with acute chest pain, fever and an abnormality in an electrocardiogram. No symptoms suggestive of myasthenia gravis were observed. Although the symptoms were alleviated by antibiotics, computed tomography (CT) showed an anterior mediastinal mass with bilateral pleural effusion. He was, therefore, diagnosed with thymoma and referred to our hospital. Surgery was performed, since the pleural effusion disappeared. The pathological examination revealed the mass to be a type B2 thymoma classified as pathological stage I (Masaoka’s classification) with a multilocular thymic cyst.     

Multilocular thymic cyst associated with Sjögren's syndrome

A 61-year-old woman, who had been diagnosed as having Sj?gren's syndrome, developed an anterior mediastinal mass. She was diagnosed with Sj?gren's syndrome with thymoma, preoperatively. Extended thymectomy was performed. Macroscopically, the mediastinal mass showed thick-walled multiloculated cavities filled with turbid yellow fluid. Microscopically, the cyst lining was continuous with thymic lobules in the wall with inflammatory process, cholesterol granuloma formation, and prominent lymph follicular hyperplasia. She was diagnosed with multilocular thymic cysts associated with Sj?gren's syndrome.     

Resection and perfusion thermochemotherapy: a new approach for the treatment of thymic malignancies with pleural spread

BACKGROUND: Thymoma and thymic carcinoma with pleural spread have a high rate of locoregional recurrence and poor prognosis. Maximal debulking coupled with aggressive local treatment could offer a chance for cure. This study evaluates the early and midterm results of operation and hyperthermic pleural perfusion with cisplatinum for thymic malignancies. METHODS: Fifteen patients (11 men), 20 to 67 years old (10 thymoma, 4 thymic carcinoma, 1 carcinoma in thymic cyst) underwent resection and hyperthermic pleural perfusion between 1995 to 2000. All had pleural spread proven before or intraoperatively. Six of the thymoma cases were recurrent. Current operation included resection without pleurectomy (9 patients), resection with pleurectomy (5), and extrapleural pneumonectomy (1 patient) with intraoperative hyperthermic pleural perfusion in all. Intrapleural temperature reached 40.3 degrees C to 43 degrees C. The total dose of cisplatinum was 150 mg or more in 14 patients. RESULTS: Complete resection (R0) was achieved in 10 patients, subtotal (R1) in 3, and partial (R2) in 2. There was no operative mortality, no hemodynamic or respiratory disturbances during perfusion, and no hematologic, neurologic, or renal complications. Complications consisted of significant bleeding (2 patients), fever (2), and air leak (1 patient). Two patients with thymic carcinoma died after 27 and 34 months, and 1 is alive with no evidence of disease at 54 months. Two patients with thymoma died after 7 and 36 months. Eight are alive after 9 to 70 months. Four patients (all R0) are alive without local recurrence more than 60 months after operation and hyperthermic pleural perfusion. CONCLUSIONS: Operation and thermochemotherpy is feasible and safe in patients with thymic tumors. This method seems to offer excellent local control for patients with stage IV-a thymic malignancies. Midterm results suggest that operation plus hyperthermic pleural perfusion may lengthen survival in stage IV-a thymoma.     

Ectopic cystic thymoma associated with Raynaud's phenomenon.

Mediastinal cystic tumors are well-marginated round lesions that comprise 12% to 18% of all mediastinal masses. These lesions include a variety of diseases with overlapping radiologic appearances and variable prognoses. Pathological examinations are almost always required for differential diagnosis. We encountered a case of anterior mediastinal tumor discovered in the process of investigation of Raynaud's phenomenon. Taking into account the tumor location, a pericardial cyst was initially suspected. However, the tumor was surgically resected and histopathological examinations demonstrated thymus-like tissue in the cyst walls. Raynaud's phenomenon greatly improved after surgery. These findings suggested that cystic thymoma originated from ectopic thymic tissue and is accompanied by paraneoplastic syndrome.     

Diagnostic utility of thymic epithelial markers CD205 (DEC205) and Foxn1 in thymic epithelial neoplasms

Foxn1 and CD205 (DEC205) are novel thymic epithelial markers that are important for thymic organogenesis and the positive selection process for thymocytes, respectively. These markers were immunohistochemically applied to a total of 77 cases of thymic epithelial neoplasms comprised of 58 cases of thymomas, 17 cases of thymic carcinomas, and 2 cases of thymic neuroendocrine carcinomas. Foxn1 was diffusely expressed in nuclear staining in all cases of type B thymoma and all but 1 case of type A thymoma, whereas the expression was generally focal in thymic carcinoma (76%). The expression was identified in all cases of mixed AB thymoma, with the expression in type A component being more variable than the one in type B component. CD205 cytoplasmic expression in the form of coarse granular staining with membranous accentuation was strong and diffuse in all cases of type B thymoma (100%), and a majority of type A thymoma (89%), and focal with variable intensity in thymic carcinoma (59%). Mixed AB thymoma demonstrated diffuse expression in type B component (100%), and variable expression in type A component (94%). Neither Foxn1 nor CD205 was expressed in 2 cases of thymic neuroendocrine carcinoma. Foxn1 was focally expressed in 13% of cutaneous squamous cell carcinoma and completely negative in cutaneous basal cell carcinoma, whereas it was completely negative in squamous cell carcinoma from head and neck, esophagus and uterine cervix, and normal tissue and malignant neoplasms from all other organs other than thymus. CD205 was expressed in 4% of nonsmall cell carcinomas of lung, 27% of squamous cell carcinoma of head and neck, and 10% of squamous cell carcinoma of esophagus, but the staining pattern was different from that of thymic epithelial neoplasm and was characterized by rather homogeneous and amorphous quality without granularity or membranous reaction. CD205 was expressed in myeloid dendritic cells of various organs and tissues as well. Foxn1 is a sensitive and specific marker for thymoma and thymic carcinoma, and it appears to be superior to CD5 and CD117 for the diagnosis of thymic carcinoma. CD205 is a sensitive and specific marker for thymoma but its sensitivity to thymic carcinoma is lower than CD5 and CD117.     

Lymphogenous and hematogenous metastasis of thymic epithelial tumors

BACKGROUND: A TNM classification has been established for various tumors. However, the TNM classification of thymic epithelial tumor has not been established yet. METHODS: We received replies to a questionnaire on thymic epithelial tumors from 115 institutes. We compiled a database of 1,320 patients with thymic epithelial tumor (1,093 thymomas, 186 thymic carcinomas, and 41 thymic carcinoids) who were treated between 1990 and 1994. We used a tentative TNM classification of thymoma presented by Yamakawa and associates in 1991. The regional lymph nodes of the thymus were classified into three groups: anterior mediastinal lymph nodes (N1), intrathoracic lymph nodes (N2), and extrathoracic lymph nodes (N3). RESULTS: The rate of lymphogenous metastasis in thymoma, thymic carcinoma, and thymic carcinoid was 1.8%, 27%, and 28%, respectively. Most tumors with lymph node metastasis metastasized to N1 (thymoma, 90%; thymic carcinoma, 69%; thymic carcinoid, 91%). The 5-year survival rates of N0, N1, and N2 thymoma were 96%, 62%, and 20%, respectively. The 5-year survival rates of N0, N1(,) N2, and N3 thymic carcinoma were 56%, 42%, 29%, and 19%, respectively. The 5-year survival rates of M0 and M1 thymoma were 95% and 57%. The 5-year survival rates of M0 and M1 thymic carcinoma were 51% and 35%. Multivariate analysis demonstrated that survival of patients with thymoma was dependent on the clinical stage of Masaoka and complete resection. In thymic carcinoma, survival was dependent on lymph node metastasis and complete resection. CONCLUSIONS: The N factor was one of the predictors of survival in thymoma and thymic carcinoma. However, M factor showed less influence on survival than T or N factors.     

Flow cytometric analysis of lymphoid cells in thymic epithelial neoplasms.

OBJECTIVE: There have been conflicts concerning the criteria for diagnosing malignant epithelial neoplasms of thymic origin. To differentiate thymic carcinomas from thymomas, the maturation stage of T-lineage lymphoid cells infiltrating thymomas and thymic carcinomas was examined by flow cytometry to associate it with the degree of tumor malignancy. METHODS: Multidimensional flow cytometric analysis was performed on the lymphoid cells extracted from 27 thymic epithelial neoplasms (14 encapsulated thymomas, ten invasive thymomas, and three thymic carcinomas) by using anti-CD3, -CD4, -CD8, -CD10, -CD20, -CD38, -CD45RA, and -CD45RO monoclonal antibodies. RESULTS: CD4 and CD8 were co-expressed on 76.8% of the lymphoid cells in encapsulated thymoma (N=14), 59.2% in invasive thymoma (N=10), and 6.7% in thymic cancer (N=3). The percentage of CD4- or CD8- single positive cells was 11.4% in encapsulated thymoma, 23.9% in invasive thymoma, and 77.7% in thymic cancer. The percentage of CD10-positive cells was 20.8% in encapsulated thymoma, 13.2% in invasive thymoma, and 6.0% in thymic cancer. The percentage of CD20-positive cell was 2.6% in encapsulated thymoma, 3.3% in invasive thymoma, and 31.6% in thymic cancer. There were significant statistical differences in the percentages of CD4/CD8 double positive cells, CD4- or CD8-single positive cells, CD10-positive cells and CD20-positive cells among the three groups. Two cases classified as invasive thymoma by pathohistological examination, however, showed the infiltration of mature lymphocytes like as thymic cancers. CONCLUSIONS: CD4+CD8+ or CD10+ T-lineage cells were the most reliable markers of the benignancy of thymic epithelial tumors. CD4- or CD8-single positive cells or CD20-positive cells were characteristic in thymic carcinoma. Flow cytometry on the maturity of lymphoid cells infiltrating thymic epithelial tumors was feasible for determining their degree of malignancy. Some invasive thymomas showed the intermediate characteristics with thymomatous epithelia and mature lymphoid cells.     

Role of flourine-18 fluorodeoxyglucose positron emission tomography in thymic pathology.

OBJECTIVE: To evaluate the utilization of positron emission tomography (PET) scan with fluorine-18 fluorodeoxyglucose (FDG) in thymic pathology. METHODS: Twenty-five consecutive patients with thymic pathology underwent FDG-PET after being evaluated by computed tomography (CT). The indication for CT was myasthenia gravis in 10, anterior mediastinal mass in 7, and recurrent thymic tumor after surgical excision in 8 patients. The results of PET were compared with results obtained by CT, and histopathologic examination of the surgical specimens. RESULTS: All mediastinal abnormal thymic tissue showed FDG uptakes. FDG-PET managed to differentiate between thymic hyperplasia and thymoma in myasthenia gravis group (n=10) in which CT images were questionable in two patients. There was one case of ectopic thymic tissue which was not diagnosed preoperatively. There were no false-negative results for both CT and FDG-PET in seven patients with thymoma presented as anterior mediastinal mass. However, PET scan predicted thymic carcinoma in one patient. PET was superior to CT scan in localization of recurrent thymoma in two patients, and equal to CT in detecting metastatic lesions in six patients during the follow-up after thymoma excision. CONCLUSIONS: In myasthenia gravis, selective use of FDG-PET is useful in differentiating thymoma from hyperplasia, especially when CT scan is controversial, but fails to recognize ectopic thymic tissue. FDG-PET may differentiate thymoma from thymic carcinoma. FDG-PET is also useful in follow-up patients, who underwent thymoma excision, when there is suspicion of recurrence or metastasis.     

Good syndrome with thymic adenosquamous carcinoma--report of a case.

A 68-year-old man with recurrent bilateral severe pneumonia and invasive thymic carcinoma was admitted to our hospital. An extended thymo-thymectomy with lymph nodes dissection was performed for an irregular shaped anterior mediastinum mass. The tumor was mainly composed of type C, adenosquamous carcinoma, and found to have a small area of types B2 and B3 thymoma. History and laboratory findings were compatible with the diagnosis of Good syndrome. Although there are some reports of thymic carcinoma arising from thymoma, this is the first report of co-existence of adenosquamous carcinomas and thymoma with Good syndrome as far as reviewed articles. Thymic carcinoma with severe infection should be examined carefully for co-existence of thymoma, and co-existence of thymoma and thymic carcinoma suggests a close histogenetic relationship between the 2 tumors.