Anterior and Superior Mediastinum

Treatment

All cysts, regardless of symptoms, should be removed to prevent future complications of infection, bleeding or mass displacement effect on adjacent normal structures. Benign mediastinal tumors should also be resected. Ganglioneuromas and neurofibromas often remain encapsulated and are easily removed. The role of surgery regarding malignant tumors spans the spectrum from diagnostic procedures to complete resection or debulking of the tumor mass to relieve complications. Patients with non-Hodgkin's lymphoma and bulky anterior mediastinal involvement occasionally require surgical intervention for respiratory symptoms, pleural effusion, or superior vena cava syndrome. Neuroblastomas, when found in early stages (I or II), should be considered for complete resection. Seminomatous tumors are treated with radiation, while germ cell tumors of other origin are treated with resection or debulking, followed by chemotherapy.

In general, the surgical approach to mediastinal masses depends on location, size and pathology. Thoracoscopy can be useful for resection or biopsy in approachable lesions, such as foregut duplications (enteric cysts and duplications, bronchogenic cysts, neurenteric cysts) and simple solid masses. Large anterior mediastinal masses are often best approached through a median sternotomy.

The common tumors in order of decreasing frequency are lymphomas, teratomas, germ cell tumors, lymphangioma (cystic hygromas) and thymic tumors. Malignant lymphomas present most frequently in older children and sometimes, diagnosis can be sought from nonmediastinal areas such as bone marrow and nodal tissues.

Teratomas are the second most common tumors of the anterior mediastinum. They are derived from multiple germ cell layers and have both cystic and solid components. Teratomas frequently have calcifications and only 25% of teratomas are malignant in pediatric patients. Serum β-HCG and AFP levels help to differentiate various germ cell tumors and are especially important postoperatively as an early marker of recurrence.

Lymphangiomas in the mediastinum frequently present as a mediastinal extension of a cervical lesion. They demonstrate extensive endothelial-lined buds within tissue planes and complete resection must be accomplished to avoid recurrence.

Thymic cysts are usually asymptomatic but can become infected or when large, produce symptoms due to mass effect. Thymolipoma is benign, but along with thymic cysts, resection is indicated for proper diagnosis and prevention of complications. Thymomas originating in the thymic epithelium are usually aggressive but account for less than 1% of mediastinal tumors. Thymomas associated with myasthenia gravis produce autoantibodies to acetylcholine receptors, which leads to progressive muscle weakness. Resection and removal has produced variable success in ameliorating or eliminating the symptoms of myasthenia gravis.

Дата добавления: 2014-10-15