Myxoid liposarcoma with low fat content

Case contributed by Dr Sergey Kitaev

Presentation

Right thigh swelling.

Patient Data

Age: 55 years
Gender: Male

There is a huge well circumscribed intramuscular mass in the anterior compartment of the right thigh, occupying almost the entire vastus lateralis muscle. The mass returns mostly high signal in T2-weighted and STIR images and appears cystic. It contains no evident macroscopic fat depositions but has amorphous areas of a high-intermediate signal in T1-weighted images and low-intermediate in STIR, which demonstrate a signal drop in the T1-out-of-phase images. After Gd administration, the mass shows a strong and heterogeneous contrast enhancement with extensive predominantly centrally located non-enhancing areas.

The mass was removed.

Histology: Myxoid liposarcoma, G2

MRI

Annotated images

Amorphous areas of a high-intermediate signal in T1-weighted images and low-intermediate in STIR (arrows), which demonstrate a signal drop in the T1-out-of-phase image (asterix). 

Case Discussion

Imaging findings of soft tissue sarcomas are not specific. Although one can definitely suggest a liposarcoma by the presence of fat fragments. Myxoid liposarcoma is a well-known type of liposarcomas affecting extremities. MRI abnormalities depend on the amount of fat, cellular, myxoid material and presence of necrosis. The last three components have hyperintense signal in T2W images and sometimes tumors appear entirely cystic on non-contrast images. In this case, the tumor didn't reveal any evident macroscopic fat tissue. The amorphous areas of a high-intermediate signal in T1-weighted images and low-intermediate in STIR (arrows) could represent both the fat and the bleeding in the mass but a signal drop in the T1-out-of-phase images (asterix) strongly suggested the intracellular lipids.

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Case information

rID: 65462
Published: 15th Jan 2019
Last edited: 16th Jan 2019
Inclusion in quiz mode: Included
Institution: MEDSI

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