Radiology Resident Case of the Week
Etiology/Pathophysiology:
LIPOSARCOMA is a malignant tumor of mesenchymal origin comprising 16-18% of all malignant soft-tissue tumor in adults especially during 5-6th decades.
Liposarcoma does not imply that the tumor is derived from fat, rather the tumor has differentiated adipose tissue. They spread hematogenously to the lung, visceral organs. Myxoid type shows tendency for serosal and pleural surfaces, subcutaneous tissue and bone.
Four types of liposarcoma:
Pathology:
Well-differentiated type consists of fat cells of various sizes. On gross examination, they resemble lipomas but with much thicker fibrous septa and thicken blood vessel walls. The CT attenuation and MR signal intensity are equal to that of fat.
Myxoid type is most common form of liposarcoma with intermediate grade malignancy. Histologically, it resembles plexiform vascular network, a mixture of stellate and spindle-shaped mesenchymal, and lipoblasts. The CT images demonstrate a relatively homogeneous or cyst-like mass with relatively sparse fat attenuation. On corresponding T1- and T2- weighted MR images, there is a very long relaxation times.
Round cell and pleomorphic types are poorly differentiated tumors of high-grade sarcoma. Histologically, round cell has sheets of round cells and lipoblasts. They often do not contain fat. Pleomorphic form has large lipoblastic multinucleated cells. The CT and MR imaging characteristics are difficult to distinguish from each other, but they usually appear as heterogeneous and lack the fat component which is common to well-differentiated and myxoid types.
Liposarcoma may present with mixed histologic types within in the same lesion. Characterizing the various types determine the prognosis and surgical planning. Withlow-grade tumors such as well-differentiated and myxoid types, a wide local excision is performed without amputation. On a high-grade tumor such as round or pleomorphic types, amputation or chemotherapy is preferred therapy.
Miscellaneous:
Imaging:
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Figures 1-3: Two distinct masses with heterogenous soft tissue and fatty attenutations.
Figure 4: Rarely seen coronal CT of the two separate masses.
Figure 5: Displaced left ureter by a mass.
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Figures 6-7: High signal intensity of well-differentiated component on T1 weight image. The myxoid component has corresponding lower signal intensity on T1 with higher signal intensity on T2.
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Figures 8-12: Angiographic procedure demonstrate a tumor blush and feeding artery.
Figure 10: A non-visible mass with mass-effect demonstrated by prominent left gonadal vein.
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Figures 13 & 14: Surgical resection of the masses.
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