Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Neurogenic tumor
- Radiologic Findings
- Chest radiograph taken at ER shows a huge left pneumothorax, associated with compressive collapse the underlying left lung. Follow-up chest radiograph post thoracostomy shows a well-defined opacity in the aortopulmonary window. Precontrast CT scan demonstrated a well-circumscribed round to oval mass with homogeneous low attenuation (H.U. 7-10) located in the aortopulmonary window. Additionally a left apical subpleural bulla was seen (not shown here). PET/CT showed no significant metabolic activity within the mass.
VATS bullectomy with mediastinal mass excision was performed. On surgery, there was no definite evidence of mass rupture or invasion to pleural space. Pathologic results were consistent with Schwannoma probably originating from the vagus nerve.
- Brief Review
- Neurilemmomas (Schwannomas) are solitary, encapsulated tumors. They consist of a population of Schwann cell, with variable amount of reticulin fiber, but do not contain nerve tissue or collagen fiber. Tumors usually have two different components: a highly ordered cellular component (Antoni type A tissue) and a loose myxoid component (Antoni type B tissue). They are more typically located in paravertebral region originated from sympathetic nervous system or intercostal nerve. Rarely they may arise from the vagus or phrenic nerves as in this case.
On CT, a neurilemmoma appears as a well-demarcated round or oval mass that may frequently demonstrate cystic degeneration and calcification. On contrast-enhanced CT, neurilemmomas demonstrate variable homogenous or heterogenous enhancement. Attenuation of the tumors on enhanced CT depends on the extent of Antoni A or B tissue and the amount of myxoid or cystic degeneration or hemorrhage.
Pneumothorax seen in this case might be due to rupture of subpleural bulla. Pneumopericardium may be resulted from micro-tear or stretching by the mediastinal tumor secondarily to pneumothorax, however surgery did not reveal the exact mechanism.
- References
- 1. Hansell DM, Armstrong P, Lynch DA, McAdams HP. Imaging of diseases of the chest, 5th ed. Elsevier: Mosby 2010:929-936.
2. Webb WR, Higgins CB. Thoracic Imaging, Lippincott Williams & Wilkins 2005:262-266.
3. Lee JY, Lee KS, Han JH, et al. Spectrum of neurogenic tumors in the thorax: CT and pathologic findings. JCAT 1999;23:399-406.
4. Cohen LM, Schwartz AM, Rockoff SD. Benign schwannomas: pathologic basis for CT inhomogeneities. AJR 1986;147:141-143.
- Keywords
- neurogenic tumor, Schwannoma, mediastinum, pneumothorax,