Post-traumatic pseudolipomas, also known as post-traumatic lipohypertrophy, are prominent increases in the volume of subcutaneous adipose tissue or even benign tumors arising at the location of a preceding blunt soft tissue trauma 1.
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Clinical presentation
Focal palpable mass, not tender and with no signs of active inflammation. Laboratory tests are usually normal 2.
Pathology
There have been two types of post-traumatic pseudolipomas described in regards to mechanism:
- repetitive blunt trauma, e.g. patients carrying heavy loads on the shoulders 1,2
- non-repetitive blunt trauma, with a marked gender predominance towards women (12:1); they can develop true lipomas (capsulated) or pseudolipomas (non-capsulated) 2
Two pathogenesis mechanisms have been suggested 1,3:
- herniation of fat is normally contained under pressure through disrupted fascial layers
- formation of new true adipose tissue caused by the differentiation of preadipocytes into mature adipocytes after trauma
Radiographic features
MRI
Post-traumatic pseudolipomas appear as areas of thickened subcutaneous fat rather than as a mass. Signal intensity follows subcutaneous fat although there is no low signal fibrous capsule. Rarely, fibrous septae may be seen. No post-contrast enhancement is seen 1.
Treatment and prognosis
Surgery (liposuctions) can be performed for aesthetic reasons 2.