Morel-Lavallée lesions are post-traumatic, closed degloving injuries.2
Morel-Lavallée lesions are often the result of skin and subcutaneous tissue quickly tearing away from the underlying fascia. This allows a range of fluids to fill the space in the form of hemolymphatic masses.1 The two most common sites are the prepatellar plate of the knee and the lateral fascia of the hip.
Morel-Lavallée lesion: MRI
- T1W: Homogeneously hypointense
- T2W: Homogeneously hyperintense
- Resemble proteinaceous fluid collection2
Under heterogeneous morphological conditions:2
- Fat necrosis
- Coagulopathy with liquefying haematoma
- Myositis ossificans with diffuse subcutaneous edema
Typically, surgical drainage is necessary if the lesion is fully developed. 1
- Bickle I. and Gaillard F. Morel-Lavellée lesion: Radiopaedia (sourced 30Jan2018): https://radiopaedia.org/articles/morel-lavallee-lesion-1
- Nair AV. et al., Morel-Lavellée lesion: A closed degloving injury that requires real attention, Indian Journal of Radiology and Imaging (2014) v24(3), 288-290.
Morel-Lavallée lesion: Example
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HISTORY: 29-year-old with anterior, medial, and lateral pain and swelling since fall while doing martial arts. Evaluate for ACL tear.
Image 1 - Axial FSE T2 Image 2 - Sagittal FSE T2
No fracture demonstrated.
Extensor tendons and cruciate ligaments are intact.
Massive superficial soft tissue swelling with very large complex fluid collection anteromedially and laterally consistent with large complex hematoma and closed degloving injury, Morel-Lavallee syndrome (images 1 and 2, green arrows). Complex hematoma measures greater than 11cm in craniocaudad dimension and extends from the medial to the anterolateral knee.
Mild patellofemoral maltracking with low-grade chondromalacia.
No traumatic meniscal tear or substantive femorotibial chondromalacia.
The collateral and posterolateral corner complexes are intact.
Popliteal neurovascular structures are unremarkable.
- Massive superficial soft tissue swelling with very large complex fluid collection anteromedially and laterally consistent with large complex hematoma and closed degloving injury (Morel-Lavallee syndrome). Hematoma measures greater than 11cm in craniocaudad dimension and extends from the medial to the anterolateral knee.
- No fracture. No ACL or meniscal tears.