A rare presentation: Morel-Lavallée lesion of the lateral thigh

Morel-Lavallée lesions (MLLs) are rare, closed degloving injuries resulting from trauma that detaches subcutaneous tissue from the underlying fascia, resulting in collections of haemolymphatic fluid. Late diagnosis can lead to pseudocapsule formation, chronic pain, and physical impairment. We describe an unusual case of a large persistent MLL on the outer aspect of the thigh that presented several years following a low-energy injury, having been initially misdiagnosed as a haematoma. Gradual expansion resulted in chronic pain and significant functional limitations. Magnetic resonance imaging revealed a substantial encapsulated subcutaneous mass consistent with a chronic MLL. Management was attained via open surgical excision with capsulectomy, quilting sutures, and closed-suction drainage. The patient experience full symptom resolution and no recurrence at follow up. This case emphasizes the need for increasing awareness amongst clinicians and demonstrates that prompt imaging and surgical treatment can avert long-term complications.