Tumours of the thymic region. Symptomatology, diagnosis, treatment, and prognosis

Endothelial cells by inactivation of VHL gene direct angiogenesis, not vasculogenesis via Twist1 accumulation associated with hemangioblastoma neovascularization

Inactivation of the VHL tumour suppressor gene is a highly frequent genetic event in the carcinogenesis of central nervous system-(CNS) hemangioblastomas (HBs). The patterning of the similar embryonic vasculogenesis is an increasing concern in HB-neovascularization, and the classic vascular endothelial growth factor (VEGF)-mediated angiogenesis driven by VHL loss-of-function from human endothelium have been questioned. With this regard, we identify a distinct, VHL silencing-driven mechanism in which human vascular endothelial cells by means of increasing cell proliferation and decreasing cell apoptosis, is concomitant with facilitating accumulation of Twist1 protein in vascular endothelial cells in vitro. Importantly, this molecular mechanism is also pinpointed in CNS-HBs, and associated with the process of HB-neovascularization. In contrast with recent studies of HB-neovascularization, these modified cells did not endow with the typical features of vasculogenesis, indicating that this is a common angiogenesis implementing the formation of the vascular network. Taken together, these findings suggest that vasculogenesis and angiogenesis may constitute complementary mechanisms for HB-neovascularization, and could provide a rational recognition of single anti-angiogenic intervention including targeting to the Twist1 signalling for HBs.

Cavernous hemangioma of thymus misdiagnosed as thymoma: a case report

INTRODUCTION

Cavernous hemangioma in the thymus is a rare presentation in mediastinal hemangiomas. The diagnosis is difficult to make promptly because both invasive and noninvasive examinations usually fail to distinguish it from other tumors of the mediastinum. Their clinical presentations depends on their size and their involvement with adjacent mediastinal structures.

CASE PRESENTATION

We treated a 52-year-old man with thymic cavernous hemangioma that was incidentally detected by chest radiography during a routine health check, and had been misdiagnosed as thymoma before the operation. The tumor was completely resected by thymectomy via video-assisted thoracic surgery. The pathological tissue was diagnosed as a cavernous hemangioma, and no phlebolith was observed in the center.

CONCLUSIONS

We reported this case of thymic cavernous hemangioma for its extremely rare occurrence in the thymus. The preoperative diagnosis remains a challenge both clinically and radiologically. It is still difficult to distinguish this tumor from other tumors in the thymus. Furthermore, biopsies might not result in a definitive diagnosis. Finally, surgical resection provides material for histopathologic diagnosis. To facilitate the preoperative diagnosis of such a rare tumor, more cases will need to be reported.

Thymoma in a child: case report and review of the literature

Thymic lesions comprise approximately 2-3% of all pediatric mediastinal tumors and include thymic cysts, hyperplasia, carcinoma, and thymomas. Thymomas, which represent less than 1% of all mediastinal tumors, are rare mediastinal tumors in the pediatric population. Fewer than 30 cases in children have been described in the literature. These tumors are typically aggressive, with poor outcomes. We report a thymoma in a 14-year-old girl and review the available literature on thymomas and their treatment.

Thymic hemangioma presenting with recurrent pleural effusion

Thymic hemangiomas are rare mediastinal tumors. In all reported cases, the diagnosis was only established after resection. Our case presented with recurrent pleural effusions mimicking advanced malignancy. Despite careful evaluation and biopsies, the diagnosis was only established after resection. We have undertaken a literature review of such unusual tumors and emphasize the importance of surgical exploration in any patient in whom a tumor lacks histological confirmation.

Malignant thymoma in children: a 20-year review

Malignant thymomas are extremely rare in children, with only 27 cases reported thus far in the pediatric surgical literature. We report four additional cases diagnosed at this institution over the past 20 years (ages 3 to 14 years). Clinical presentations included superior vena cava syndrome, cough, dyspnea, cyanosis, enlarging mediastinal mass, spontaneous pneumothorax, and pleuropericardial effusion. Three patients underwent incomplete resection of the mass or biopsy because of "unresectability" and were treated with radiotherapy and adjunctive chemotherapy. One patient underwent near complete macroscopic resection as well as radiotherapy and chemotherapy. All patients died at intervals ranging from 6 months to 2 1/2 years after diagnosis. Three patients were found to have metastatic disease prior to death or at autopsy. In one case, the initial pathological diagnosis was lymphocytic thymoma. After ultrastructural studies were performed, the diagnosis was changed to thymic T-cell lymphoma. This patient subsequently developed acute lymphoblastic leukemia 3 months after surgical resection followed by radiotherapy. Malignant thymomas are highly aggressive tumors in children. A radical surgical approach with complete excision of the tumor and contiguous structures in continuity, with adjunctive radiotherapy and chemotherapy remains the only hope for survival in children with these rare lesions.

Hodgkin's disease of the thymus: a rare mediastinal cystic mass

We report a 14-year-old patient referred to us because of chest pain. A huge upper anterior mediastinal mass with several cystic spaces within it was found and resected. Pathologic diagnosis was nodular sclerosis Hodgkin's disease of the thymus. Radiotherapy was started after accurate surgical staging, and the patient remains free of disease 24 months later. Cavitation of the gland in Hodgkin's disease of the thymus should be taken into consideration when dealing with upper anterior mediastinal cystic masses in children. Surgery is probably unavoidable in this group of patients and, interestingly, can account in part for the relatively good prognosis in this localized form of the disease.

Prolonged exposure to M. faeni in strain II guinea-pigs: pulmonary interstitial inflammation

Models of hypersensitivity pneumonitis (HP) should exhibit progression of pulmonary histological abnormalities during continuing challenges. Strain II guinea-pigs were sensitized with Micropolyspora faeni and received 2, 4, or 8 weekly intratracheal (i.t.) particulate M. faeni challenges. Control animals received normal saline (NS). Four days after the last exposure, randomly selected microscopic fields of lung (200/animal) were judged to be normal or abnormal. If abnormal, the location and nature of the abnormalities were determined. Compared with NS treated guinea-pigs, those exposed to 2, 4 and 8 weekly M. faeni challenges exhibited more extensive (P less than 0.001) pulmonary histological abnormalities which involved both the intraalveolar and interstitial compartments. More extensive abnormalities in the 8 week group compared with the 4 week group were caused by increased extent of interstitial mononuclear cell infiltration. The extent of pulmonary interstitial histological abnormalities transiently (four challenges) decreases, but then increases, so that progressive pulmonary inflammation occurs during continuing challenges.

Tumors of the thymus and thymic region: I. Clinicopathological studies on thymomas

A series of 43 patients with thymoma was reviewed. The patients were classified with respect to some factors of prognostic significance. The tumors were reclassified histologically, and a staging system with three defined stage-groups was applied to the series on the basis of operative findings and histological examination of surgical specimens. Surgical-pathological staging is of high prognostic and therapeutic importance in thymomas. Complete removal of the tumor was possible in the 25 patients with stage I or II disease and in 14 of the 18 patients with stage III tumors. Pleural metastases were observed in half of the patients with stage III disease. Even patients with extensive local spread or pleural metastases were subject to tumor resection. The treatment of choice is radical resection along in stage I; radical extirpation and, if indicated, postoperative radiotherapy in stage II; and radical resection whenever possible, even in cases of pleural spread, in stage III, with postoperative radiotherapy and chemotherapy. Myasthenia gravis is an indication rather than a contraindication to radical treatment of thymoma, although some patients may deterioratte. The importance of total thymectomy is stressed.