Atypical lipomatous tumor (ALT)

Case contributed by Valerio Giacalone


The patient had a large mass on the right thigh.

Patient Data

Age: 70 years
Gender: Female

In the vastus intermedius muscle of the right thigh, there is a voluminous expansive mass isointense to adipose tissue in T1- and T2-weighted sequences, with suppression of the fat signal in Fat-Sat sequences. It has a craniocaudal extension of about 24 cm, a maximum transverse diameter of 9 cm, and an anteroposterior diameter of about 7.5 cm.
The proximal and mid-distal portion of the tumor has some septa, hypointense in T1-weighted sequences (with a maximum thickness of about 3.5 mm), hyperintense in T2, and fat-suppressed sequences, which show minimal intra- and periseptal enhancement after administration of paramagnetic contrast medium.
The main neuro-vascular bundles do not appear to be compromised and there is no infiltration of the femur.
The fascial plane is intact.

Case Discussion

The voluminous mass in the right thigh showed intensitometric characteristics compatible with an adipose tumor. In fact, some septa were appreciated with a thickness of more than 3 mm, which showed slight enhancement after administration of a paramagnetic contrast medium. 
Therefore a biopsy was recommended with the suspicion of well-differentiated liposarcoma.
Four biopsy specimens were taken and the histological diagnosis was of an atypical lipomatous tumor (ALT).
The patient underwent surgical removal.

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