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| US | CT | MRI |
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Posttraumatic pseudolipoma (PTL) | Well-delineated hyperechoic subcutaneous mass | Well-delineated subcutaneous mass with Hounsfield attenuation of fat | Homogenous unencapsulated mass isointense to fat on all sequences |
| No posterior acoustic attenuation or enhancement | | T1WI-hyperintense |
| | T2WI-hypointense |
| | Fat suppression—hypointense |
| | Absence of a well-defined low signal intensity fibrous capsule |
| | No enhancement following administration of intravenous Gadolinium |
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Lipoma | Similar to PTL | Similar to PTL | Signal intensity as PTL |
| Usually homogenous | Usually homogenous |
| May contain thin internal septa (<2 mm) | A well-defined low signal intensity fibrous capsule is usually present |
| May appear as complex with thick septa (>2 mm) and nonlipomatous components | There may be mild to moderate enhancement following administration of intravenous gadolinium |
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Liposarcoma (variable appearance according to histological type according to WHO classification | Heterogeneous, multilobulated usually well-defined fatty mass | Contains large lipomatous and prominent nonlipomatous components such as thick internal septa (>2 mm) | Heterogeneous
Contains large lipomatous and prominent nonlipomatous components such as thick internal septa (>2 mm) and nodules |
| Usually located in the deep soft tissues of the extremities particularly thigh, head and neck, trunk, and retroperitoneum | May contain focal nodules | Moderate to marked enhancement of septa following administration of intravenous gadolinium |
| Calcification or metaplastic ossification may be seen | |
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