Mediastinal liposarcoma

Case contributed by Yune Kwong


Incidental finding

Patient Data

Age: 65-70 years
Gender: Male

Abnormal mediastinal mass deviating trachea to the left.


Mixed fatty/solid mass in middle mediastinum, extending superiorly into the neck. Leftward deviation of the trachea.

Nuclear medicine

Only mild FDG uptake in the solid components of the middle mediastinal mass.


Right neck plus mediastinal mass: A smooth encapsulated, lobulated mass is inked with silver nitrate and serially sliced. The cut surface is yellow tan, soft and lobulated. Areas of hemorrhage or necrosis are not seen. Involvement of the capsule macroscopically is not identified.

Sections of demonstrate a tumor composed predominantly of adipocytes. Throughout the tumor there are background areas of fibrosis and collagen,scattered within which there are atypical cells. The atypical cells are characterized by nuclear enlargement and irregularity and some multinucleate forms are identified. These cells have a small amount of ampophilic cytoplasm, with no striations evident.  The mitotic rate is not elevated.  Rare lipoblasts are present. Immunoperoxidase staining is negative for actin and desmin and shows patchy positivity with CD34.

DIAGNOSIS: Well-differentiated liposarcoma (lipoma-like).

Case Discussion

The differential for a fat-containing mediastinal mass includes:

Liposarcomas present more commonly in the anterior than posterior mediastinum. They are usually large and can infiltrate the mediastinum. Patients typically are middle-aged and present with dyspnea or chest pain. Well differentiated liposarcomas have large amounts of fat as well as soft tissue, as in this case (lack of PET uptake suggested low-grade tumor pre-operatively). High-grade liposarcomas do not have significant amounts of fat.

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