Primary mediastinal tumors. Part 1: tumors of the anterior mediastinum

Diagnosis of mediastinal masses and principles of surgical tactics and technique for their treatment

The diagnosis of a mediastinal mass is first based on clinical features, supplemented by epidemiological data and laboratory results providing information on the nature and localization of the mass. The diagnosis is then defined further on the basis of imaging studies. The first examinations required are standard radiographs, ultrasound scan or computed tomography scan and occasionally magnetic resonance imaging (MRI), angiography, and scintigraphy. These studies are followed by a thoracoscopy, mediastinoscopy, and the necessary biopsy techniques. Finally, the author describes the general principles of surgical tactics and techniques that generally lead to a total regression of the disease.

Surgical anatomy of the mediastinum

After a short description of mediastinal anatomy and embryology, the authors illustrate the division of the mediastinum, based on criteria of either surgical anatomy or radiological anatomy. Lastly, they discuss the topographical distribution of the mediastinal masses in anterior, visceral, and posterior compartments of the mediastinum.

Primary tumors of the mediastinum

BACKGROUND AND OBJECTIVES

Diagnostic and therapeutic approaches to mediastinal tumors have changed over the past three decades. We reviewed our recent experience with these tumors and assessed the role of a multidisciplinary treatment approach.

METHODS

A retrospective review of 124 patients with primary mediastinal tumors over a 25-year period.

RESULTS

Median age was 35 years. Symptoms were present in 86 of 124 (69%) patients. One hundred and eleven of 124 (90%) tumors were malignant. Distant metastases were present at diagnosis in 14 of 124 (11%) patients. The most common tumor was thymoma (38/124, 31%), followed by germ-cell tumor (29/124, 23%), lymphoma (24/124, 19%), and neurogenic tumors (15/124, 12%). Seventy-four of 124 (60%) patients underwent resection, 88 (71%) received chemotherapy, and 97 (78%) received radiation therapy. Tumor recurrence occurred in 52% (47/91) of patients who initially had a complete resection or response to treatment. Median time to recurrence was 10 months. Overall median survival was 44 months. Metastatic disease at presentation (P = 0.02) and tumor recurrence (P = 0.00001) were the only significant independent predictors of survival on multivariate analysis.

CONCLUSIONS

Malignant primary mediastinal tumors often require multimodality treatment. Despite improvements in survival with multimodality treatment, death from recurrent disease remains a problem.

Occurrence of malignant non-germ cell components in primary mediastinal germ cell tumours

METHODS

Thirty-five patients with primary mediastinal germ cell tumours (PMGCT) underwent primary thoracotomy in a 30-year period (1965-1994). Of the 35 patients, 12 had benign teratomas, five pure seminomas and 18 non-seminomatous germ cell tumours.

RESULTS

Out of 18 non-seminomatous germ cell tumours, 14 comprised more than one malignant component. In two cases malignant teratomas had an additional malignant non-germ cell component: one a mixed sarcomatous component and the other a neuroendocrinal component. There were different methods of treatment between 1965 and 1994. All but one of patients with seminomas survived for 5 years. Among 18 patients with malignant PMGCT, all but two died within 5 years (mean survival rate was 15 months).

CONCLUSIONS

When planning treatment of patients with malignant PMGCT we have to take into account the fact that malignant non-germ-cell components may occur. In this circumstances, surgical resection after initial chemotherapy is recommended.