A CASE OF MOREL LAVALLEE LESION

Abstract

Morel-Lavalle effusions are the result of
the skin and subcutaneous fatty tissue
abruptlyseparating from the underlying
fascia, a traumatic lesion that has been
termed closed deglovinginjury. These
effusions are common in the trochanteric
region and proximal thigh, where they
havebeen referred to as Morel-Lavalle
lesions . In this region, the dermis contains
a rich vascular plexusthat pierces
the fascia lata. The disrupted capillaries
may continuously drain into the perifascial
plane,filling up the virtual cavity with
blood, lymph, and debris. An inflammatory
reaction commonly createsa peripheral
capsule, which may account for the
self-perpetuation and occasional slow
growth of theprocess .Morel-Lavalle lesions
have been listed under different
names, including posttraumatic softtissue
cyst, pseudocyst, Morel-Lavalle
extravasation, or Morel-Lavalle effusion.
MRI protocol includedaxial and coronal
spin-echo T1-weighted sequence, axial
T2, coronal STIR sequences. gadoliniumdimeglumine
is used as contrast agent. A thin hypointense
ring, likely representing a hemosiderin-
laden capsule, circumscribed all
lesions. They show homogeneous hyperintensity
on both T1- andT2-weighted sequences
and surrounded by a hypointense
peripheral ring. This T1 signal-intensity isprobably
related to the existence of methemoglobin,
characteristic of subacute hematomas.
Methemoglobin is first observed on
the periphery of subacute hematomas and
produces a concentricring sign.Longstanding
Morel-Lavalle lesions show a MRI
pattern that includes variable signalintensity
on T1 and hyperintensity on T2-
weighted sequences, and a hypointense
peripheral rim.peripheral enhancement
also be present. The heterogeneous hyperintensity
on T2-weightedsequences correlates
with the existence of hemosiderin
deposition, granulation tissue, necrotic debris,
fibrin, and blood clots characteristic of
chronic organizing hematoma. The hypointenseperipheral
ring represent a hemosiderin-
laden fibrous capsule with mild
inflammatory infiltrate, which is said to be
relevant for the self-perpetuation of

the lesion. Finally, the internal enhancement
is probably related to the capillary formation
in the lesion The history of trauma, the characteristic
location, and the MRI features may
contribute to a correct diagnosis in such
cases.