The management of deep-seated, lowgrade lipomatous lesions

Abstract

Deep-seated, low-grade lipomatous lesions detected on imaging often cause uncertainty for diagnosis and treatment. Confidently distinguishing lipomas from well-differentiated liposarcomas is often not possible on imaging. The approach to management of such lesions varies widely between institutions. Applying an evidenced-based approach set around published literature that clearly highlights how criteria such as lesion size, location, age and imaging features can be used to predict the risk of well-differentiated liposarcomas and subsequent de-differentiation would seem sensible. Our aim is to review the literature and produce a unified, evidence-based guideline that will be a useful tool for managing these lesions.

Figure 1.

Intramuscular lipoma within the flexor compartment of the forearm. (a) Axial T₁ weighted image shows only thin septations but no thick septa or nodules. (b) Axial T₂ fat suppressed image shows homogenous fat suppression without appreciable septa or non-fatty component.

Figure 2.

Intramuscular liposarcoma within the thigh (vastus lateralis muscle). (a) Axial T₁ weighted image and (b) axial T₂ fat suppressed image showing a simple, predominantly fatty intramuscular lipomatous lesion with a few intervening muscle fibres but no thick septa or nodules. Percutaneous biopsy was performed with immunohistochemistry assessment confirming this as a WDL.

Figure 3.

Intramuscular liposarcoma in the right thigh. (a) Sagittal T₁ weighted image demonstrates thick septa (arrow) and nodular component (arrow head). (b) Sagittal T₂ fat suppressed image demonstrates the non-fatty component as high signal septa (arrow) and nodule (arrow head).

Figure 4.

Spindle cell lipoma variant in the paraspinal muscles. (a) Sagittal T₁ weighted image and (b) sagittal T₂ fat suppressed image demonstrate mixture of fatty (arrows) and non-fatty components (arrow heads) with incomplete signal suppression on the fat saturated image.

Figure 5.

Intramuscular lipoma. Coronal T₁ weighted image shows the characteristic inter-digitating margins (arrows) of an intramuscular lipoma within the obturator externus muscle.

Figure 6.

Retroperitoneal liposarcoma. Axial contrast enhanced CT abdomen and pelvis examination demonstrates a large retroperitoneal fatty mass (arrows) with more complex, solid areas internally. The mass is significantly displacing bowel loops.

Figure 7.

Presacral myelolipoma. Axial T₁ weighted image demonstrates the fatty (arrow) and non-fatty haematopoietic (arrow head) components within the lesion in a typical presacral position.

Figure 8.

Suggested pathway for management of deep lipomatous lesions.