Morel Lavallee Lesion: A Shear Fascia-nating Soft Tissue Injury

Morel-Lavallée lesions (MLLs), first described by their namesake, French physician Victor-Auguste-François Morel-Lavallée, in 1863, represent a distinct category of soft-tissue degloving injuries. These injuries occur when a shearing force disrupts the connection between subcutaneous tissue and fascia, severing lymphatic vessels and capillaries, and leading to an encapsulated collection of lymph, blood, and necrotic fat. Because this space is deep and enclosed, the fluid accumulation cannot easily drain or resolve spontaneously and often an inflammatory capsule develops, further inhibiting resorption. Undiagnosed, patients go on to develop chronic pain, infection, skin necrosis, progressive neurovascular deficits, and, in severe cases, potential loss of limb and even life. For emergency medicine physicians, the implications are significant: Recognizing MLLs when a trauma patient first presents to the ED is crucial to avoiding long-term disability, morbidity, and mortality. We report a classic presentation of a MLL, highlighting how a thorough history, physical, and bedside POCUS allowed the diagnosis to be made after a delayed presentation to the ER, potentially sparing the patient significant morbidity and chronicity.