Computed tomographic staging of anterior mediastinal neoplasms

Giant Benign Mediastinal Masses Extending into the Pleural Cavity

Introduction  The aim of the study was to evaluate the results of surgery to remove huge mediastinal masses and their pathology. Surgical resection was chosen for accurate diagnosis and treatment of the huge mediastinal masses extending into the pleural cavity. Methods  Records were reviewed for eight patients who had the diagnosis of huge benign mediastinal masses and who underwent operation; details of the patients and operations were recorded. Results  Mean age was 34.5 (range 22 to 44) years, and male-to-female ratio was 2:6. Computed tomography and magnetic resonance imaging (MRI) were used to evaluate the location and extent of the abnormality and to characterize the tissue components of the mass. Most of the tumors were located in the posterior mediastinum. The most frequent presenting symptom was exertional dyspnea. The majority of cases underwent posterolateral thoracotomy, and complete resection was possible in seven patients. Partial resection could only be performed in one. The mean diameter of the resected masses was 15 × 10 cm. Histopathologic examination revealed 3 neurogenic tumors, 2 teratomas, 1 thymolipoma, and 1 ectopic thyroid, and 1 hemangioma. Minor complication was seen in two cases. Conclusion  The presurgical thoracic MRI provided correct diagnosis along with radiologic characterization and topography. Surgery must be the preferred treatment in huge benign mediastinal masses.

Application of Robotic-Assisted Techniques to the Surgical Evaluation and Treatment of the Anterior Mediastinum

BACKGROUND

We report our initial experience with the application of robotic-assisted technologies to the treatment of diseases of the anterior mediastinum.

METHODS

Between October 2001 and December 2003, 18 consecutive patients with anterior mediastinal masses were referred for diagnosis and treatment. Fifteen patients underwent robotic-assisted surgery with the da Vinci robotic system. A single surgical team performed all operations. Resection was accomplished by either median sternotomy or robotic-assisted techniques.

RESULTS

Fourteen patients underwent successful robotic-assisted thymectomy. One patient underwent robotic-assisted biopsy of a mass that was later determined to be a poorly differentiated carcinoma, 3 patients underwent complete thymectomy by median sternotomy for biopsy-proven extracapsular thymoma, 7 patients had thymoma, and 3 had myasthenia gravis. There were 2 patients each with benign thymic cysts and thymic hyperplasia. Primary thymic carcinoid, thymolipoma, papillary thyroid cancer, and poorly differentiated carcinoma were present in 1 patient each. No conversions, intraoperative complications, or deaths occurred in the 15 patients who underwent robotic-assisted resection. The mean operative time was 96 minutes (range 62 to 132 minutes). The mean robotic time was 48 minutes (range 22 to 76). The median hospital stay was 2 days. All patients are doing well, with a median follow-up of 1 year.

CONCLUSIONS

Robotic-assisted surgery of the anterior mediastinum, and particularly thymectomy, can be performed safely and efficiently. The increased visualization and instrument dexterity afforded by this technology provides an optimal minimally invasive approach to the anterior mediastinum. From this experience we have formulated a comprehensive treatment algorithm for the surgical evaluation and treatment of patients with anterior mediastinal diseases.

A review of open biopsy for mediastinal masses

OBJECTIVE

To review the recent experience with biopsied mediastinal lesions in children and to assess the impact of recent advances in imaging and surgical techniques on diagnosis.

METHODOLOGY

The clinical and radiological features of 55 patients who had mediastinal biopsies at The Royal Alexandra Hospital For Children (RAHC) over 15 years were reviewed.

RESULTS

Fifty-five patients presented to RAHC between 1978 and 1993 with lesions of the mediastinum requiring biopsy of that site. Thirty-one of the 55 (56%) lesions were malignant. Neurogenic tumours were the most common (40%). In order of frequency the following lesions were found: neuroblastoma (15), teratoma (eight), non-Hodgkin's lymphoma (NHL; eight), enteric cyst/duplication (five), ganglioneuroma (five), bronchogenic cyst (three), ganglioneuroblastoma (two), lymphangioma (two), abscess (two), Hodgkin's lymphoma (HL; two), oesophageal granuloma (one), Langerhan's cell histiocytosis (one), congenital fibromatosis (one). Eighty-two per cent of neurogenic tumours were located in the posterior mediastinum, while 75% of teratomas and 100% lymphoid tumours were located anteriorly. Symptoms were generally unhelpful in establishing a specific diagnosis and in 27% of cases the lesions were discovered incidentally. Physical signs, such as thoracic inlet obstruction and neurological findings, were helpful clinically in localizing lesions within the mediastinum. Chest radiography enabled lesions to be subdivided within the mediastinum. This localization, in combination with the age at presentation, predicted the tissue diagnosis. Computerized tomography (CT) and magnetic resonance imaging (MRI) further defined the lesion and demonstrated involvement of adjacent structures. Histology, however, was essential to distinguish benign from malignant lesions.

CONCLUSIONS

The clinical presentation of mediastinal masses is often non-specific or incidental. Despite recent advances in imaging technology and biopsy techniques, full histological examination is required to exclude malignancy.

PET imaging of primary mediastinal tumours

Mediastinal masses include a wide variety of tumours and remain an interesting diagnostic challenge for radiologist. We performed positron emission tomography (PET) studies of primary mediastinal tumours in order to predict the malignancy of these tumours preoperatively. Twenty-two patients with primary mediastinal tumours were studied with PET using 2-deoxy-2-[18F]fluoro-D-glucose (FDG). The histological findings of surgical pathology or biopsy, or mediastinoscopy were compared with those of computerised tomography (CT) and PET. PET images were evaluated semiquantitatively using the differential uptake ratio (DUR). Increased FDG uptake was observed in nine of ten patients with malignant tumours, including thymic carcinomas, lymphomas, invasive thymomas and a case of sarcoidosis. A moderate level of FDG uptake was found in a myeloma, non-invasive thymomas, and a schwannoma, whereas a low uptake was observed in a teratoma and various benign cysts. The mean FDG uptake of malignant tumours was significantly higher than that of benign tumours. Both thymic cancer and invasive thymoma showed a high FDG uptake. CT examination resulted in three false-negative and two false-positive cases when used in predicting tumour invasion, while PET was associated with a false-positive and a false-negative case. In conclusion, the use of FDG with PET is clinically helpful in evaluating the malignant nature of primary mediastinal tumours. Our results also suggest that a high FDG uptake reflects the invasiveness of malignant nature of thymic tumours.

Primary mediastinal neoplasms (other than thymoma)

Primary mediastinal neoplasms encompass a long list of histologically diverse lesions that can arise from a wide variety of mediastinal structures. Recent advances in diagnostic techniques have considerably enhanced the evaluation of the mediastinum with use of noninvasive or minimally invasive procedures. In adults, most primary mediastinal neoplasms can be classified in one of four categories: thymus-derived neoplasms, neurogenic tumors, lymphomas, or germ cell neoplasms. In children, neurogenic tumors (especially neuroblastomas) and lymphomas are most frequently encountered. Because of the presence of many vital structures in the confined thoracic cavity, even benign mediastinal neoplasms can cause severe symptoms from the mass effect and therefore warrant a carefully planned management strategy. With modern therapeutic and surgical interventions, associated morbidity and mortality can often be substantially decreased.

Management of anterior mediastinal tumors

The most common neoplasms of the anterior mediastinum are thymomas, lymphomas, and germ cell tumors. Surgical exploration was the routine approach to the diagnosis and management of these tumors. This is no longer true. The appropriate initial treatment of these neoplasms varies from surgical resection to radiation therapy to systemic chemotherapy. Except for the small well-encapsulated anterior mediastinal mass, it is imperative that a definitive tissue diagnosis be obtained before initiating treatment. An overview of these tumors and the specific approaches to their treatment are detailed.