대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Mature Cystic Teratoma ruptured into the lung

Radiologic Findings

Chest radiograph shows consolidation with multiple air-fluid levels in RUL.
Pre- & post-contrast enhanced CT scans show cystic mass with fat density and definite enhancing wall in anterior mediastinum.
On pre-contrast enhanced CT scan at level of carina shows communication between the cystic mass and necrotic area of the lung.
Mediastinal and lung-window images show consolidation in RUL with multiple abscesses some of which show air-fluid levels.

Brief Review

A teratoma is a neoplasm derived from more than one embryonic germ layer and believed to develop in cell rests within, or in intimate contract with, the thymus.
Benign cystic teratomas are more common than the malignant forms.
They usually consist predominantly of ectodermal elements such as skin, sebaceous material, hair, and calcification- hence the expression "dermoid cyst"- along with smooth muscle and respiratory epithelium.
Benign cystic teratomas are usually asymptomatic (up to 53%) and symptoms are caused by local compression, rupture, or infection.
The most common symptoms are chest pain, cough that is usually productive, dyspnea, and fever.
Occasionally patients have pneumonia, hemoptysis, superior vena caval syndrome, or trichoptysis (expectoration of hair).
Benign cystic teratomas usually produce mass in the anterior mediastinum but a few are found in the posterior mediastinum or lung.
CT findings are variable. Water density in the cystic component is common, and fat density is seen in one fourth to one half of the patients.
A definite cyst wall, which may show curvilinear calcification, is often visible.
These tumors rarely rupture into the adjacent structures, such as the pleural space, pericardium, lung parenchyma, or tracheobronchial tree.
Proteolytic or digestive enzymes derived from the tumor have been proposed as the cause of tumoral rupture.
When the tumor is ruptured, these enzymes can cause inflammation and necrosis of adjacent organs.
All ruptured mediastinal teratomas had a tendency to display inhomogeneity of the internal component, whereas 90% of unruptured masses showed homogenous densities of internal components in each compartment of the mass.
Ancillary CT findings (such as a fat-containing mass, consolidation, or atelectasis in the adjacent lung) are important for detecting rupture in the mediastinal teratomas.
Pleural effusion was one of the most common ancillary CT findings (57%) in ruptured mediastinal teratomas.
Pericardial effusion, especially in-patients with a teratoma adhering to the pericardium, also appeared to suggest rupture of the tumor into the pericardium.

References

1. Nichols CR. Mediastinal germ cell tumors; clinical features and biologic correlates. Chest 1991;99:472-479
2. Suzuki M, Takashima T, Itoh H, et al. Computed tomography of mediastinal teratomas. J Comput Assist Tomogr 1983; 7:74-76
3. Choi SJ, Lee JS, Song KS, Lim TH. Mediastinal teratoma: CT differentiation of ruptured and unruptured tumors. AJR 1998;171:591-597

Keywords

Mediastinum, Benign tumor,