대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Cystic Lymphangioma

Radiologic Findings

Chest radiographs show a large homogeneous opacity in the right paratracheal area (Fig 1).

CT scans show that the mass is of water density and that it possesses a sharp interface with contiguous lung parenchyma. The mass displaces and partially surrounds adjacent right brachiocephalic vein. It relates intimately to the posterior surface of the superior vena cava and the right posterolateral wall of the trachea (Fig. 2, 3).

Brief Review

Lymphangiomas are rare benign lesions of lymphatic origin, representing 0.7-4.5% of all mediastinal tumors and occurring most commonly in the superior or anterior mediastinum. Lymphangiomas are most common in the neck and axilla. Although 10% of cervical lymphangiomas extend into mediastinum, less than 5% of lymphangiomas are limited to the mediastinum itself. The origin of lymphangiomas is controversial; they may be developmental, hamartomatous, or neoplastic. But as with hemangiomas, lymphangiomas probably represent developmental anomalies rather than true neoplasms.
Because of their soft consistency, lymphangiomas seldom cause symptoms, even when large, occasionally, however, they cause symptoms by compressing the tracheobronchial tree, or the superior vena cava or its major tributaries. In younger patients particularly, a soft tissue mass may be visible in the neck. Chylothorax develops in some cases.
Most lymphangiomas are present at birth and are detected in the first 2 years of life, but they can be seen in adults as well. In adults, it is common for a lymphangioma to be localized in the mediastinum.
Lymphangiomas are classified into three groups, depending on the size of the lymphatic channels: 1) capillary lymphangiomas, 2) cavernous lymphangiomas, 3) cystic lymphangiomas. Histologically, lymphangiomas are thin-walled, cystic, multilocular tumors, lined by endothelial cells and containing clear yellow fluid. Their wall consists of connective tissue, smooth muscle, fat, blood vessels, nerve, or lymphatic tissue.
On plain radiographs, lymphangiomas form well-defined, round, lobulated masses, usually in the anterior or superior mediasitnum. Most mediastinal lymphangiomas appear homogeneous and cystic on CT, but some appear inhomogeneous because of the presence of protein, fluid, blood, or fat in the lesion. Although minimal enhancement cannot be excluded in the lesions showing inhomogeneous attenuation, enhancement is not apparent after intravenous infusion of contrast medium. Although most lymphangiomas are multiloculated on histologic examination, CT demonstration of delicate septa is rare. Most lymphangiomas have thin walls, but cases with thicker walls have been reported. Calcification in the lesion is very rare. Displacement or compression of the surrounding mediastinal structures is absent or minimal in most mediastinal lymphangiomas despite their large size.

References

1. Shaffer K, Rosado-de-Christenson ML, Patz EF, Young S, Farver CF. Thoracic lymphangioma in adults: CT and MR imaging features. AJR 1994;162:283-289
2. Miyake H, Shiga M, Takaki H, Hata H, Onishi R, Mori H. Mediastinal lymphangiomas in adults: CT findings. J Thorac Imaging 1996;11:83-85
3. Naidich DP, Webb WR, Muller NL, Krinsky GA, Zerhouni EA, Siegelman SS. Mediastinum: In Computed tomography and magnetic resonance of the thorax. 3rd ed. Philadelphia. Lippincott-Raven publishers, 1999;128-130
4. Fraser R, Muller NL, Colman N, Pare PB. Fraser and Pare's Diagnosis of diseases of the chest. 4th ed. W.B. Saunder's Company, Philadelphia, 1999, 2921-2924

Keywords

Mediastinum, Congenital,