Age / Sex : 54 / M

Chief complaint :  a focal soft tissue swelling on the anterolateral proximal thigh  4weeks after traffic accident

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy of Juhng Seon-Kwan, Wonkwang University School of Medicine

Discussion

Answer:  Morel-Lavallee lesion

Findings:

A focal bulging of the anterolateral soft tissue contour of proximal thigh on plain radiographs. Two separated abnormal fluid collections in the anterolateral subcutaneous fat tissue area with homogeneous bright signal intensity onT2 weighted images, low SI on T1WI, and contrast enhancement of the relatively thin and uniform thick peripheral wall like region on postcontrast fat saturated T1WI. Fat-fluid level in the posterior lesion.

A focal bone marrow edema in the distal femur on sagittal images is due to combined intraarticular fracture of the lateral femoral condyle.  

Differential Diagnosis:

 Hematoma (hyperacute or resolving)

Fat necrosis

Abscess

Discussion:

 The Morel-Lavallée lesion is a closed soft-tissue degloving injury commonly associated with high-energy trauma. The thigh, hip, and pelvic region are the most commonly affected locations. Timely identification and management of a Morel-Lavallée lesion is crucial because distracting injuries in the polytraumatized patient can result in a missed or delayed diagnosis. Bacterial colonization of these closed soft-tissue injuries has resulted in their association with high rates of perioperative infection.

Recently, MRI has been used to characterize and classify these lesions. Six distinct lesion patterns have been described. Lesion age and MRI imaging are used to distinguish each type. The six radiographic features used in the classification of each lesion include shape,lesion appearance, T1-weighted MRI characteristics, T2-weighted MRI characteristics, and the presence and enhancement of a capsule and lesion. In general, each type is correlated with the increasing complexity and chronicity of the lesion. The fluid-filled pocket, if present, is often identifiable on T1-and T2-weighted MRI sequences. Many lesions occupy an expansive surface area; the average size is reported to be 30 ·12 cm. MRI characteristics can help to define lesion age. Acute lesions are hypointense on T1-weighted images and hyperintense on T2-weighted sequences. Subacute lesions are homogenously hyperintense on T1- and T2-weighted sequences, with a peripheral capsule that is hypointense on both T1- and T2-weighted sequences. Not uncommonly, the area may demonstrate heterogeneous composition, depending on the varied age of its contents, because old hematoma settles and serous fluid accumulates within the empty space. Other atypical MRI features include perifascial dissection,

fatty layer lacerations, and the development of multiple septations.

Definitive management is dictated by the size, location, and age of the injury and ranges from percutaneous drainage to open débridement and irrigation. Chronic lesions may lead to the development of pseudocysts and contour deformities of the extremity.

References:

1. Diviti S, Gupta N, Hooda K, Sharma K, Lo L. Morel-Lavallee Lesions-Review of Pathophysiology, Clinical Findings, Imaging Findings and Management. J Clin Diagn Res. 2017; 11(4): TE01–TE04.


2. Scolaro JA, Chao T, Zamorano DP. The Morel-Lavallee lesion:diagnosis and management. J Am Acad Orthop Surg. 2016;24(10):667-672.


3. Nair AV, Nazar PK, Sekhar R, Ramachandran PV, Moorthy S. Morel-Lavallée lesion: A closed degloving injury that requires real attention. Indian J Radiol Imaging. 2014; 24(3): 288–290.


4. Bonilla-Yoon I, Masih S, Patel DB, et al:The Morel-Lavallée lesion:Pathophysiology, clinical presentation,imaging features, and treatment options. Emerg Radiol 2014;21(1):35-43.


5. Mellado JM, Bencardino JT: Morel-Lavallée lesion: Review with emphasis on MR imaging. Magn Reson Imaging Clin N Am 2005;13(4):775-782.


6. Tseng S, Tornetta P. III: Percutaneous management of Morel-Lavallee lesions. J Bone Joint Surg Am 2006;88(1):92-96.


7. Mellado JM, Perez del Palomar L, Diz L, Ramos A, Sauri A. Long standing Morel-Lavallée lesions of the trochanteric region and proximal thigh: MRI features in five patients. AJR Am J Roentgenol. 2004;182:1289–94.


8. Gilbert BC, Bui-Mansfield LT, Dejong S. MRI of a Morel-Lavallee Lesion. AJR Am J Roentgenol. 2004;182:1347–8


9. Mallado JM, Bencardino JT. Morel-Lavellee lesion: Review with Emphasis on MR imaging. Magn Reson Imaging Clin N Am. 2005;13:775–82.