Mediastinal lymphangioma

Imaging diagnostics of lymphangioma

On computed tomography (CT), lymphangioma is visualized as a lobulated mass with smooth contours. A specific sign is the tumor's ability to "wrap around" (envelopes) and encompass adjacent mediastinal structures without causing significant displacement. The lesion typically demonstrates homogeneous density characteristic of fluid. In some cases, thin septa (septations) are identified within the structure. Meanwhile, the outer wall of the cyst itself may not be visualized at all.

Magnetic resonance imaging (MRI) complements the picture with the following features:

• T1-weighted images (T1WI) show heterogeneous signal intensity.
• T2-weighted images (T2WI) typically show high signal intensity, confirming the fluid nature of the lesion.

Treatment and prognosis

Due to the specific infiltrating (insinuating) growth pattern of lymphangiomas, complete surgical removal (resection) is often significantly difficult. Remaining tumor elements can lead to regrowth of the lesion. For this reason, patients require mandatory and careful dynamic follow-up (follow-up) using imaging modalities for the timely detection of possible recurrences.

Differential diagnosis: Haemangiomas

When analyzing mediastinal lesions, lymphangiomas must be differentiated from other rare vascular tumors — haemangiomas (Haemangiomas). They consist of a network of communicating vascular channels, areas of thrombosis, and elements of fibrous stroma. Capillary, venous, and cavernous forms are distinguished (the latter accounting for about 75% of all cases).

Haemangiomas are more often detected in young patients, and in 50% of cases they are completely asymptomatic. Clinical manifestations usually occur only upon compression of surrounding structures.

CT presentation of haemangioma:

• Following intravenous contrast administration, contrast enhancement (enhancement) is observed, which can be dense (dense), focal, diffuse, peripheral, or central.
• In 10–20% of cases, punctate calcifications or phleboliths (calcified thrombi) are visualized within the lesion structure, which is an important diagnostic marker.

Differential diagnosis: Fatty lesions

Another large group for differential diagnosis consists of mediastinal fatty lesions. Normally, adipose tissue is present in the mediastinum without a capsule, is distributed evenly, and its volume increases with age. In patients with pronounced obesity, large accumulations of fat (fat pads / fat pads) can form in the cardiophrenic angles, which can mimic a mass (mass) on scans.

Pathological fat distributions can be either diffuse or focal in nature:

1. Mediastinal lipomatosis — a benign excess accumulation of unencapsulated fat of normal histological structure. It occurs against the background of obesity, steroid therapy, or Cushing's disease. On radiographs, it manifests as a smooth, symmetric widening of the superior mediastinum. CT shows uncontained low-density (fatty) tissue that clearly outlines anatomical structures without signs of a local tumor.
2. Mediastinal lipomas — benign, well-circumscribed lesions accounting for 2% of all mediastinal tumors. They are most commonly localized in the prevascular space. On CT, they have uniform fat density, smooth borders, and are clearly demarcated from adjacent structures. They do not compress organs unless they reach giant sizes.
3. Mediastinal liposarcomas — rare malignant tumors of any location. Unlike lipomas, on CT they demonstrate heterogeneous density, a significant soft tissue component, poorly defined borders, and signs of invasion. Histologically, they are characterized by cellular atypia, mitotic activity, and neovascularization.
4. Lipoblastoma — a benign tumor of childhood containing fat and soft tissue. On CT, it may be visually similar to liposarcoma.
5. Angiomyolipoma and myelolipoma — extremely rare benign tumors for the mediastinum with a combination of fat and soft tissue density, often indistinguishable from liposarcoma on imaging.
6. Fat-containing hernias — protrusion of omental fat (omental fat). Morgagni hernia typically manifests as a mass in the right cardiophrenic angle, while Bochdalek hernia manifests on the left in the posterior regions (due to fat penetration through a diaphragmatic defect).

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• MRI semiotics of mediastinal cystic lesions
• Histological subtypes of haemangiomas (capillary, cavernous, venous)
• Mediastinal lipomatosis: association with endocrine pathology
• Differential diagnosis of lipoma and liposarcoma
• Fat-containing diaphragmatic hernias (Morgagni and Bochdalek)

Other topics in the «Chest Radiology» section

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