Sonographic features of Myxoid Liposarcoma are not been extensively reported: US shows a hypo-echoic,
solid,
ovalar and well-defined mass (4).
Doppler US analysis reveals predominant a peripheral vascularization (in some cases is observed a vascular peduncle penetrating into the lesion) [Fig.2].
This appearance may be similar to Lipoma,
the most common benign tumor of soft-tissues,
composed of mature adipocytes (10).
Usually,
Lipoma is a hyperechoic and encapsulated lesion; however,
in the 20% of patient,
Lipoma appears hypoechoic with minimal color-Doppler flow (11).
Myxoid Liposarcoma has a typical appearance on MRI imaging: the high water content of myxoid stroma is reflected as hypo-intensity in T1w-images,
and hyper-intensity in T2w-images (1,
4).
The most important feature is the presence of fat foci (variable percentage) into the lesion,
organized in linear septa or small nodules: the use of fat-suppression/fat saturation sequences is very helpful to detect these fat foci in the tumor mass (4)[Fig.
3].
At gadolinium-enhanced MR imaging,
the contrast enhancement of Myxoid Liposarcoma is intense and homogeneous or heterogeneous: it depends on increase cellularity and vascularity (1,
9,
12,
13)[Fig.
4].
One of the most important differential diagnosis is with Myxoma,
a benign soft-tissue lesion which contains myxoid stroma and has a similar MRI aspect to Myxoid Liposarcoma: hypo-intense in T1w-images,
hyper-intense on T2w-images [Fig.
5 e Fig.
6].
Myxoma may have a heterogeneous internal enhancement with gadolinium.
-Extra-muscular Myxoma is rare (9% inter-muscular,
9% subcutaneous): Myxomas are mainly intra-muscular (82%),
most represented in the tight (10,
15);
-Myxoma doesn’t contain intra-lesional fat: it presents a peritumoral fat rind,
visible on T1-w images (14);
-Its contrast enhancement is variable,
mild or moderate (10),
lower than Myxoid Liposarcoma,
which usually shows an intense contrast enhancement [Fig.
7].
The definitive diagnosis is histopathological.