Primary Mediastinal Neoplasms

Abstract

neoplasms and lymphoma characteristically affect the anterior mediastinum while neurogenic neoplasms typically occur in the paravertebral regions. Patients with mediastinal neoplasms may be asymptomatic or may present because of symptoms of compression or local invasion. Patients with thymoma may also present with paraneoplastic syndromes including myasthenia gravis. Thymoma is the most common primary anterior mediastinal neoplasm and usually manifests as a unilateral soft tissue mass with lobular contours that may exhibit local invasion or drop pleural metastases. Mature teratoma often demonstrates a spherical morphology and cystic change; intrinsic fat attenuation in such a lesion is virtually diagnostic. Malignant germ cell neoplasms almost exclusively affect men and manifest as anterior mediastinal soft tissue masses that may be homogeneous or exhibit areas of low attenuation from central necrosis and are indistinguishable from lymphoma with nodal coalescence on imaging. Neurogenic neoplasms are paravertebral lesions that may produce skeletal erosion and intraspinal extension and are optimally evaluated with MRI. Imaging diagnosis of primary mediastinal neoplasms requires identification of a mediastinal mass, placement of the mass in a specific mediastinal compartment and characterization of the lesion with cross-sectional imaging to formulate a focused differential diagnosis and appropriate management recommendations.