Fact-sheet: Paraosteal lipoma
Updated on 09/17/2021 at 12:16 PM
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Definition
Asymptomatic in the vast majority of cases, unless there is adjacent vascular or nerve compression.
Muscular amyotrophy is possible.
Palpation reveals a firm, immobile mass, not fixed to the skin plane.
Slow evolution.
Paraosteal lipoma is a benign adipose tumor developing in contact with the periosteum, without a cleavage plane from it, which may cause a periosteal reaction and, very rarely, a bony outgrowth.
Affects adults in the 5th and 6th decades without sex predominance.
0.3% of all lipomas.
No malignant transformation.
Clinical features
Asymptomatic in the vast majority of cases, unless there is adjacent vascular or nerve compression.
Muscular amyotrophy is possible.
Palpation reveals a firm, immobile mass, not fixed to the skin plane.
Slow evolution.
Radiography
Well-defined mass of fat density, in contact with the bone cortex.
Adjacent bone cortex modified:
- bone erosion
- periosteal reaction
- bony outgrowth
CT
Well-defined, juxtacortical mass of fat density (-30HU to -130HU).
Septations within the mass.
+/- Associated vascular compression.
Bone reaction identical to that seen on plain radiographs.
MRI
T1: mass with signal identical to subcutaneous fat.
T2: intermediate signal.
Septa hypointense on all sequences (fibrous nature).
Possible T2-hyperintense, T1-hypointense areas adjacent to bony outgrowths due to hyaline cartilage.
Nuclear medicine
Possible increased uptake in the area of new bone formation
Management
If symptomatic: complete resection of the tumor, the bony outgrowth, and its periosteal attachments.
Differential diagnosis
Osteochondroma -
but no fatty mass in contact with it -
and continuity with the cancellous bone and cortex of the host bone.
Liposarcoma: -
poorly defined, heterogeneous mass -
cleavage plane with the periosteum -
soft tissue component enhancing after contrast injection
