Imaging Features of Morel-Lavallée Lesions

Abstract

Objectives:To review the imaging characteristics of Morel-Lavallée lesions with both ultrasound and magnetic resonance imaging (MRI).Materials and Methods:We retrospectively analyzed 31 patients (mean age = 46 years), diagnosed with a Morel-Lavallée lesion, on ultrasound (n = 15) or MRI (n = 16). On ultrasound the echogenicity, internal septations, hyperechoic fat globules, compressibility and Doppler signal were evaluated. On MRI, T1- and T2-signal intensity, capsule presence, internal septations, enhancement, mass-effect and fluid-fluid levels were assessed. The MR images were classified according to the classification of Mellado and Bencardino.Results:Most of the lesions were situated peritrochanteric, around the knee or the lower leg. The majority of the lesions had a heterogeneous hypoechoic appearance with septations and intralesional fat globules. On MRI, most of the collections were hypointense on T1-weighted images and hyperintense on T2-weighted images. Half of the collections were encapsulated, and most collections demonstrated septations. The collections were classified as seroma (n = 10), subacute hematoma (n = 2) and chronic organizing hematoma (n = 5).Conclusion:Ultrasound is the imaging method of choice to diagnose Morel-Lavallée lesions. MRI can be of use in selected cases (extension in different compartments, large collections, superinfection). Characteristic imaging features include a fusiform fluid collection between the subcutaneous fat and the underlying fascia with internal septations and fat globules. On MRI, six types of ML lesion can be differentiated, with the seroma, the subacute hematoma, and the chronic organizing hematoma being the most frequently observed lesions.

Morel-Lavallée Lesion in the Sacrococcygeal Area with Associated Coccygeal Fracture

“…CT may show a fluid-fluid level caused by sedimentation of cellular blood components and a peripheral capsule surrounding the mass, especially in chronic lesions 2). Some lesions may contain internal septations and fat globules 3)…”

“…Blood, lymphatic fluid, and debris collect and fill the space 1718). The most commonly affected sites are the thigh, knee, hip, and pelvic area, but the lesion can also occur in other areas, such as the lower leg, abdomen, periscapular region, and lumbosacral region 3). The treatment method depends on size, duration, location, associated injuries, and presence of a capsule.…”

MRI of the Morel-Lavallée lesion – a case series

“… 2 , 3 , 4 Consequently, a dead space is formed, which can potentially fill with haemolymph, debris and fat, resulting in a formation of heterogeneous collection. 2 , 3 , 5 , 6 , 7 , 8 , 9 …”

“…Peritrochanteric region is particularly sensitive to this injury because of the increased mobility of the soft tissue in this area, the superficially located bone, strong underlying fascia lata attaching to the iliotibial band and a rich vascular plexus piercing the fascia lata . 5 , 7 , 8 …”

“…It is seen as homogeneously hypointense on T1 and hyperintense on T2 MRI ( Figure 1 ). 5 , 12 It can be acute or chronic and is mostly noncapsulated. 5 , 11 …”