# An Atypical Presentation of Morel–Lavallée Syndrome Following Blunt Trauma

## TL;DR

A rare case of Morel-Lavallée syndrome in the thigh is described, emphasizing the importance of early diagnosis and treatment to avoid complications.

## Contribution

This case report highlights the atypical presentation of Morel-Lavallée syndrome and advocates for early surgical intervention.

## Key findings

- MLS can present atypical in the medial thigh and may mimic other conditions like cellulitis or abscess.
- Early surgical drainage within 72 hours of injury led to successful treatment and no postoperative complications.
- Ultrasonography is effective for early detection, while MRI is preferred for chronic cases.

## Abstract

Morel-Lavallée syndrome (MLS) refers to a closed internal degloving injury resulting from tangential shearing forces, which cause separation of the skin and subcutaneous layers from the underlying deep fascia, with subsequent collection of hemolymphatic fluid and devitalized adipose tissue in the created potential space. Despite its rarity, MLS contributes substantially to soft-tissue shear injuries and is commonly underdiagnosed, with consequent delays in treatment and related complications.

A 44-year-old female reported localized pain with a progressively enlarging swelling involving the inferomedial aspect of the right thigh subsequent to a road-traffic accident. Clinical examination revealed a large, well-defined, fluctuant, non-tender swelling with overlying bluish-black discoloration and no neurovascular compromise. Ultrasonography reported a well-circumscribed fluid collection located between the subcutaneous adipose tissue and the underlying fascia, with no associated bony injury on radiography. Given a high index of suspicion for MLS, early surgical intervention was undertaken within 72 hours of injury. Incision and drainage revealed clear separation of the subcutaneous tissue from the fascia, with evacuation of approximately 200 cc of hematoma. The postoperative course was uneventful, and secondary suturing was performed on day five, with no evidence of infection or residual collection during the inpatient stay.

MLS commonly involves the peri-trochanteric region but may present at atypical sites such as the medial thigh. The lesion can mimic cellulitis, abscess, or hematoma, underscoring the importance of clinical suspicion. Previous literature indicates that ultrasonography is useful for the early detection of Morel-Lavallée lesions, whereas magnetic resonance imaging is preferred for the evaluation of established or chronic lesions. Evidence derived mainly from retrospective series and narrative reviews suggests that early percutaneous or surgical drainage has been associated with lower rates of recurrence and morbidity; however, outcomes may vary, and the quality of evidence remains limited. In patients with persistent or recurrent collections, definitive surgical management such as capsulectomy, minimally invasive approaches, or sclerotherapy, with doxycycline emerging as an effective sclerosant, has been described.

This case report highlights the importance of maintaining a high index of suspicion for MLS in atypical clinical presentations and demonstrates that early recognition, followed by timely drainage and structured postoperative care, may help prevent progression to chronicity, recurrence, and secondary infection.