IS Case 599: Grade I myxoid liposarcoma

Alena Levit, MD

Imaging Sciences URMC

Imaging Sciences URMC 2010
Publication Date: 2011-11-17

History

The patient is a 14-year-old girl with painless posterior right thigh mass.

Findings

Consistent with liposarcoma, however the signal pattern for fat is not seen.

Diagnosis

Grade I myxoid liposarcoma

Discussion

Liposarcoma is the second most common soft tissue sarcoma in adults. It accounts for approximately 16-20% of all malignant soft tissue tumors. Liposarcoma is a malignant tumor of mesenchymal origin with lipoblasts. At histologic analysis, liposarcomas may be classified as well differentiated, myxoid, pleomorphic, or round cell.

Myxoid liposarcoma is the second most common subtype of liposarcoma, representing 30-40% of all liposarcomas in the extremities. It occurs most commonly in the lower extremity, particularly the thigh. Myxoid liposarcoma occur in the intermuscular facial planes or deep-seated areas. Most patients with these tumors are aged 18-67 years. Patients with liposarcoma in the extremities tend to be a little younger than those with tumors in the retroperitoneum.

Most common signs and symptoms include a painless mass. If symptoms due occur, they are usually from compression of neurovascular bundle or abdominal organs. Other clinical presentation is weight loss despite soft tissue mass. Biologic behavior and prognosis is determined by histologic type and size. Metastases are found in approximately 50% of the patients and overall 5-year survival is 60%.

Imaging findings:

Radiographs: Nonspecific soft tissue mass. Ossification within the tumor may occur about 10% of the time.

CT: Heterogeneous soft tissue mass with fatty and soft tissue components. Fat is frequently not detected radiologically. Liposarcoma enhances on CECT.

MR: Since the fat content is often less than 10-25% of the tumor volume, MRI may not show the typical features of lipomatous tumor. A myxoid liposarcoma that contains abundant water can mimic a cystic lesion. Contrast-enhanced MRI is useful in distinguishing cystic or necrotic lesions from solid, cellular lesions. Myxoid liposarcoma exhibits low signal intensity on non-enhanced T1WI and high SI on T2WI. In contrast, lipomas and well-differentiated liposarcomas typically show high SI secondary to the relatively high fat content.

Myxoid liposarcomas has three enhancement patterns: homogeneous, heterogeneous, and no enhancement.

References

  1. Evans HL. Liposarcomas and atypical lipomatous tumors: a study of 66 cases followed for a minimum of 10 years. Surg Pathol 1988; 1:41-54.
  2. Kransdorf MJ. Malignant soft tissue tumors in a large referral population: distribution of diagnoses by age, sex, and location. AJR Am J Roentgenol. 1995 Jan;164(1):129-34. PMID: 7998525
  3. Jelinek JS, Kransdorf MJ, Shmookler BM, Aboulafia AJ, Malawer MM. Liposarcoma of the extremities: MR and CT findings in the histologic subtypes. Radiology. 1993 Feb;186(2):455-9. PMID: 8421750
  4. Sundaram M, Baran G, Merenda G, McDonald DJ. Myxoid liposarcoma: magnetic resonance imaging appearances with clinical and histological correlation. Skeletal Radiol. 1990;19(5):359-62. PMID: 2377902

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