Page 126 - Journal of Special Operations Medicine - Spring 2016

Figure 1 Photo indicating width of area of fluctuance on The patient was evaluated in the ED by the on-call or-
patient’s lower back. thopedic surgeon and ultimately referred to a tertiary
care facility for definitive management.

Discussion

The typical presentation is a patient report of a tender,
swollen area often with fluctuance and either an acute or
remote history of trauma to the site. Clinically, Morel-
Lavallée lesions typically present as an enlarging painful
lesion within the anterolateral portion of the affected
2
thigh with soft tissue swelling and fluctuance. Other
reported sites of involvement are the trunk, lumbar, pre-
patellar, and scapular regions. The 2012 Case Reports in
Orthopedics described 29 published reports of Morel-
Lavallée lesions from 14 countries, with a total of 204
3
lesions in 195 patients. The most common anatomic
location was the greater trochanter/hip (36%), followed
by the thigh (24%) and the pelvis (19%). 3
Figure 2 Photo indicating of area of fluctuance on patient’s
lower back. The cavity formed by the shearing of tissue creates a
potential space or “sixth cavity” into which blood can
accumulate. The amount of accumulated blood depends
mainly on the size of the degloved area and the rate of
bleeding into this potential space. During the initial as-
sessment, the mechanism of injury, as well as any large
area of bruising in the absence of an obvious source of se-
vere bleeding, should raise suspicion for Morel-Lavallée
lesion. Large Morel-Lavallée lesions may require surgical
4
interventions for both bleeding control and to prevent in-
5
fection or skin necrosis. However, these effusions may be
initially missed or may take some time to develop, which
can make clinical diagnosis difficult. In longstanding

cases, these lesions may subsequently enlarge and become
painful, leading to misdiagnosis of soft tissue tumor. In
contrast, these lesion types have also been described to
Figure 3 Transverse soft tissue ultrasound image of lumbar have spontaneously decreased in size, remained a stable
area, demonstrating deep, fascial anechoic fluid collection. size over time, or progressively enlarged. 1
Imaging options include US, CT, and magnetic reso-
nance imaging (MRI). Features noted with US are re-
lated to the age of the hematoma, which will appear
as a focal complex collection located superficial to the
muscle plane and deep to the hypodermis. A CT scan
will show a fluid level from the settling of blood com-
ponents and can also show a capsule if present. MRI
is the modality of choice in the evaluation of Morel-
Lavallée lesion, as it is able to discriminate chronicity
and internal contents. Radiologists have developed a

classification system defined by imaging features such
and subcutaneous fat were unremarkable. The imaging as lesion shape, signal characteristics, enhancement, and
characteristics and mechanism were thought most sug- the presence or absence of a capsule that distinguish the
gestive of a posttraumatic Morel-Lavallée fluid collec- different types. 6,7
tion. A subsequent computed tomography (CT) scan
performed to further evaluate the lesion confirmed the Early diagnosis and management are essential, because
findings reported by ultrasound. any delay in diagnosis or missed lesion may lead to the

110 Journal of Special Operations Medicine Volume 16, Edition 1/Spring 2016