대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Myxoid Liposarcoma

Radiologic Findings

Plain chest films demonstrate a large soft tissue mass obliterating Rt. cardiac border, with well defined margin which is suggested to mediastinal mass. Very slow growth of the mass was identified as compared with old chest radiograph taken 7 years ago. Pre-contrast CT scan showed well defined soft tissue mass with homogeneous low density (HU 17-20). On post-contrast CT, multiple scattered enhancing foci are noted mainly at the peripheral areas of the tumor. The patient underwent surgical resection. The specimen of this tumor was well-encapsulated and had myxoid nature internally without solid component. Microscopic finding showed myxoid tumor composed of lobulating nodules of irregular spindle cells. The pathological diagnosis was a myxoid liposarcoma.

Brief Review

Liposarcoma is second in frequency only to malignant fibrous histiocytoma among the soft tissue sarcomas. It is found most often in the thigh or retroperitoneum. Primary liposarcoma of the mediastinum is extremely rare, comprising only 0.13 ?0.75 % of mediastinal tumors. The tumor affects older people and often presents with larger sized than does liposcarcoma at other sites.
There are four histological subtypes of liposarcoma which determine clinical progress. Well-differentiated and myxoid-type liposarcoma have a more benign course compared with round-cell and pleomorphic type. Myxoid type is the most common type comprising 50% of liposarcomas. Myxoid liposarcoma has an expansive rather than infiltrative growth.
Usually liposarcomas have a homogeneous soft tissue appearance on a CT scan, but well-differentiated portions can be more radiodense and calcifications may be noted.
Radiologic findings of several reported cases of mediastinal liposarcomas were homogeneous or inhomogeneous masses of low density at any part of the mediastinum, with nodular enhancing portions or peripheral frond-like enhancement, and some calcification on CT. Fat component may or may not be found in the mass.
The differential diagnosis of this case includes malignant thymoma, lymphoma, and germ cell tumor.

References

1. JI Jung, H Kim, SW Kang and SH Park Radiologic findings in myxoid liposarcoma of the anterior mediastinum. Br J Radiol. 1998 Sep;71(849):975-6.
2. Attal H, Jensen J, and Reyes CV. Myxoid liposarcoma of the anterior mediastinum. Diagnosis by fine needle aspiration biopsy. Acta Cytol. 1995 May-Jun;39(3):511-3.
3. Mikkilineni RS, Bhat S, Cheng AW, and Prevosti LG. Liposcarcoma of the posterior mediastinum in a child. Chest 1994 Oct;106(4):1288-9.

Keywords

Mediastinum, Malignant tumor,