Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Schwannoma
- Radiologic Findings
- On the chest radiograph, a 4.5 cm smooth marginated mass with broad base on mediastinum is seen extending above the clavicle.
The mass demonstrates heterogeneous low signal intensity on T1WI and multiple fluid-fluid levels on T2WI. Post-contrast MRI shows of the mass shows enhancement of septa, mural nodule and a shell-like wall.
- Brief Review
- Schwannomas are most common encapsulated neurogenic tumor that have components of Antoni type A tissue (highly ordered cellular component) and Antoni type B tissue (loose myxoid component). They are usually located in paravertebral region in patients in second to fifth decade.
The schwannoma appears as sharply marginated, round, elliptical, or lobulated extrapleural mass. Abutting rib or vertebral deformity or enlargement of a neural foramen may be visible in about 50% of cases.
On CT, the tumor appear as well-demarcated round or oval low attenuation mass, that shows heterogeneous enhancement due to variable cellularity including lipidized foamy cells, cystic areas, xanthomatous and hemorrhagic changes.
On MR, the lesion demonstrates low to intermediate signal intensity on T1-weighted images and very high signal intensity on T2-weighted images. The various degenerative change makes schwannoma appear heterogeneous. The Antoni A component shows relatively low SI on T2WI whereas the Antoni B component shows very high SI on T2WI. Fluid-fluid levels could be seen due to hemorrhagic changes. The split fat sign may be seen on MRI images as a fine rind of fat around the lesion, best appreciated on T1 weighted images.
- References
- 1. Hansell DM, Armstrong P, Lynch DA, McAdams HP. Imaging of diseases of the chest, 4th ed. Elsevier: Mosby 2005:951-958.
2. Webb WR, Higgins CB. Thoracic Imaging, Lippincott Williams & Wilkins 2005:262-266.
3. T Nakazono, CS White, F Yamaski et al. MRI
- Keywords
- Mediastinum, Paravertebral, Benign tumor,