The Imaging features are different depending on the histological subtype.

Computed tomography (CT) is widely used for the initial evaluation of liposarcomas. On non-contrast CT scans, liposarcomas typically appear as well-defined soft tissue masses with varying degrees of fat attenuation due to their adipose tissue origin. The presence of mature adipose tissue within the tumor manifests as regions of low attenuation (< -30 Hounsfield Units) on CT images. However, some liposarcomas may contain non-adipose components, leading to heterogeneous attenuation patterns. Higher-grade liposarcomas may exhibit areas of necrosis, calcification, or hemorrhage, contributing to their heterogeneous appearance on CT scans. Contrast-enhanced CT imaging reveals heterogeneous enhancement within the tumor, particularly in the non-adipose regions, reflecting the presence of viable tumor tissue with increased vascularity. In Well-differentiated and dedifferentiated liposarcomas calcifications might be found.

Magnetic resonance imaging (MRI) is considered the imaging modality of choice for evaluating soft tissue tumors, including liposarcomas, due to its superior soft tissue contrast resolution. On MRI, liposarcomas typically demonstrate hyperintense signal intensity on T1-weighted images due to the presence of adipose tissue, which appears hypointense on T2-weighted images. However, the signal intensity of liposarcomas may vary depending on their histological subtype and the proportion of adipose and non-adipose components. High-grade liposarcomas may exhibit heterogeneous signal intensity on both T1- and T2-weighted images due to areas of necrosis, hemorrhage, or cellular proliferation. Post-contrast MRI imaging demonstrates heterogeneous enhancement within the tumor, reflecting the presence of viable tumor tissue and neovascularization.

Distinguishing liposarcoma from other soft tissue tumors is essential for appropriate treatment planning. The main differential diagnoses include:

1. Lipoma: Lipomas are benign soft tissue tumors composed of mature adipose tissue. Unlike liposarcomas, lipomas typically demonstrate homogeneous fat attenuation on CT and uniform hyperintense signal intensity on T1-weighted MRI images without evidence of non-adipose components.
2. Undifferentiated Pleomorphic Sarcoma (UPS): UPS is another common soft tissue sarcoma that may mimic liposarcoma on imaging. UPS typically appears as a heterogeneous soft tissue mass with variable signal intensity on MRI and heterogeneous enhancement on post-contrast imaging. However, UPS lacks the characteristic fat attenuation seen in liposarcomas on CT imaging.
3. Other Soft Tissue Sarcomas: Various soft tissue sarcomas, such as leiomyosarcoma, fibrosarcoma, and malignant peripheral nerve sheath tumor (MPNST), may exhibit imaging features overlapping with liposarcoma. Careful evaluation of the imaging characteristics, including the presence of adipose tissue, vascularity, and necrosis, is essential for accurate differentiation.
4. Angiomyilipoma (AML): On imaging studies such as CT or MRI, angiomyolipoma typically appears as a well-defined, heterogeneous mass with areas of fat attenuation or signal intensity (due to adipose tissue), thickened blood vessels, and smooth muscle components. AMLs may show enhancement on contrast-enhanced imaging. Liposarcomas can also contain fatty components, but they often exhibit more aggressive features compared to AML. Liposarcomas may demonstrate infiltrative margins, heterogeneous enhancement, and signs of local invasion into surrounding tissues on imaging studies. The presence of necrosis, hemorrhage, or calcifications within the mass can also be indicative of
5. Myelolipoma: On imaging studies such as CT or MRI, myelolipomas typically appear as well-defined, heterogeneous masses with areas of fat attenuation/signal intensity (due to adipose tissue) and areas of higher attenuation/intensity corresponding to hematopoietic elements.

Imaging Pitfalls of Liposarcoma:

Liposarcoma is presenting a diagnostic challenge due to its diverse histological subtypes and variable imaging features. While imaging modalities like CT and MRI play a crucial role in the evaluation of liposarcoma, several pitfalls can complicate the diagnosis and management of these tumors.

1. Heterogeneous Appearance: One of the key imaging pitfalls of liposarcoma is its heterogeneous appearance on imaging studies. While liposarcomas typically contain adipose tissue, they may also exhibit areas of non-adipose components such as fibrous tissue, myxoid matrix, necrosis, or hemorrhage. This heterogeneity can lead to variable signal intensity on MRI and variable attenuation on CT, making it challenging to differentiate liposarcomas from other soft tissue tumors or benign lesions.
2. Overlapping Features with Benign Lesions: Another pitfall in the imaging of liposarcoma is its overlapping features with benign lesions such as lipomas or lipomatous tumors. Benign lipomatous lesions may demonstrate similar imaging characteristics, including fat attenuation on CT and hyperintense signal intensity on T1-weighted MRI images. Therefore, distinguishing between benign lipomatous lesions and liposarcoma based on imaging features alone can be challenging, necessitating histopathological confirmation.
3. Myxoid Liposarcoma Mimicking Cystic Lesions: Myxoid liposarcoma, a subtype of liposarcoma, is characterized by a myxoid matrix with scattered lipoblasts. On imaging, myxoid liposarcomas may mimic cystic lesions due to their high water content, resulting in hyperintense signal intensity on T2-weighted MRI images. This can lead to a misdiagnosis of cystic lesions or other benign processes, highlighting the importance of considering liposarcoma in the differential diagnosis of cystic soft tissue masses.
4. Necrosis and Hemorrhage: Higher-grade liposarcomas often exhibit areas of necrosis and hemorrhage, which can further complicate their imaging appearance. Necrotic and hemorrhagic areas within the tumor may appear hypointense on T1-weighted MRI images and hyperintense on T2-weighted images, resembling other soft tissue malignancies or inflammatory processes. Additionally, the presence of necrosis and hemorrhage can affect contrast enhancement patterns on post-contrast imaging.

Because of these pitfalls diagnosis of liposarcoma is based on a combination of imaging features and histopathological findings.