BACKGROUND: The Morel-Lavallée lesion is a post-traumatic collection of fluid 
arising after a 'closed degloving injury' has caused the separation of the skin 
and subcutis from the underlying muscular fascia. It usually occurs in the 
trochanteric region or proximal thigh.
CASE DESCRIPTION: A 36-year-old obese man was referred to the emergency 
department by his general practitioner for fever and pain in the right lower 
abdominal quadrant. Blood testing revealed elevated infection parameters. As 
appendicitis was suspected, a CT scan of the abdomen was performed. This 
revealed a Morel-Lavallée lesion, which he had sustained 9 months earlier when 
he had been hit by a car while riding his bicycle. A rapid recovery ensued after 
ultrasound-guided percutaneous drainage and treatment with antibiotics.
CONCLUSION: A Morel-Lavallée lesion, which could manifest even months later, 
should be considered after any traumatic injury. Ultrasound, CT and MRI are 
useful tools for proper diagnosis. There is no consensus about treatment in 
either the acute or the chronic phase to date.