Orbital Soft Tissues Sarcomas/Liposarcoma

Abstract

Primary liposarcoma of the orbit is a rare tumor. Features include:

• Variable age at presentation: mean 4th–5th decade.

• Female preponderance.

• Predominantly intraconal or superior orbit.

• Variable tumor margin: some well-defined.

• Less commonly reported: tumors involving the medial, lateral, inferior orbit or the subconjunctival space.

• In general, imaging appearance depends on the tumor grade and the amount of fat component.

On computed tomography (CT):

• Nonspecific soft tissue density mass.

• Occasional fat density (measures in the range of negative HU [−50] to [−150]).

• Occasional calcification.

• Variable contrast enhancement: the fat density region usually does not enhance, while the soft tissue density component usually enhances.

Magnetic resonance imaging (MRI) reveals:

• Varied signal intensity on T1-weighted and T2-weighted images.

• If there is a pure fat component, it will follow fat signal, for example, at the contralateral orbit and subcutaneous fat on all (including fat suppressed) sequences.

• Large proportion show nonfatty soft tissue intensity; some can demonstrate fat component; chemical shift as a low intensity signal may appear at the periphery of the tumor (this misregistration stems from the difference in resonance between fat and water and is more prominent on older generation MRI sequences).

• Without a fat component, the imaging is nonspecific.

• The soft tissue density component usually enhances following contrast; additional signs that may aid in differentiating from simple lipoma include inhomogeneity, thick septae, and prominent vessels.