대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Organizing Hematoma in Extrapleural Space

Radiologic Findings

A large, well-defined mass with inhomogeneous low attenuation and multiple nodular calcifications.No significant contrast enhancement of the mass is seen.
A portion of peripheral fatty attenuation with medially displaced parietal pleura (arrow) suggests the extrapleural origin of the mass.
Our DDx. were
1) Neurogenic tumor (with or without malignant potential).
2) Organizing hematoma.
3) Benign fibrous tumor of the pleura (with central necrosis).
4) Sarcoma of the chest wall (due to its huge size).
Fluoroscopy-guided core biopsy was done successfully but revealed blood cells only.
Mass excision was done. On surgery, the mass was extrapleural in location.
The specimen was a soft cystic mass, measuring 16x11 cm in size. On cut section, the mass showed diffuse cavitary changes and contains gray-black, necrotic material. The cavitary wall measured 1 cm in maximal thickness.
The patient had a recent history of admission in other hospital due to putaminal hemorrhage one month before. There was no known history of significant chest trauma.

Brief Review

Understanding the anatomy of the intrapleural and extrapleural compartment is important in interpreting CT scans of pleural and pleural space disease. The normal visceral and parietal pleurae together form a thickness of approximately 0.2-0.4mm. Just external to the parietal pleura are a fat layer, the endothoracic fascia, and the innermost intercostal muscle.
On high-resolution CT scans of healthy individuals, the pleura and these structures are seen in combination as a line 1-2mm thick in the anterolateral and posterolateral intercostal spaces. Beyond this line and between the ribs lies the intercostal fat, which contains the intercostal vessels and nerve. Outside this fat layer lie the intercostal muscles. Normally, on conventional CT scans the visceral and parietal pleurae internal to the rib surface are not visible, and extension of a soft-tissue stripe internal to the rib is therefore considered a sign of pleural thickening or effusion. The extrapleural fat (the fat layer between the parietal pleura and the endothoracic fascia) commonly thickens in association with thickening of the parietal pleura.
Conventional CT with contrast enhancement is also useful in detecting hematoma. The attenuation of blood, unlike that of other constituents of pleural effusions, is greater than that of water. This increase in attenuation in attributed to the density of the hemoglobin.
The extrapleural hematoma result from malpositioned chest tubes, complications during placement of a catheter in the central vein, infection and other conditions of intercostal artery laceration. Patients with thickening of the parietal pleura may be at greater risk for extrapleural tube placement. When chest-tube drainage is poor, contrast-enhanced CT should be considered to confirm the location of a thoracostomy tube in relation to the pleural and extrapleural spaces.
In summary, medially displaced extrapleural fat shown on CT scans is useful in revealing extrapleural fluid and distinguishing it from pleural fluid. A fluid collection of increased attenuation suggests a hematoma.

References

1. Aquino SL, Chiles C, Oaks T. Displaced extrapleural fat as revealed by CT scanning: evidence of extrapleural hematoma. AJR 1997 Sep;169(3):687-9

Keywords

Chest wall, Pleura, Trauma,