The Morel-Lavallée lesion (MLL) is a rarely reported closed degloving injury, in which shearing forces have lead to break off subcutaneous tissues from the underlying fascia. Lumbar MLL have been rarely reported to date, explaining that patients are frequently misdiagnosed. While patients could be treated conservatively or with non-invasive procedures, delayed diagnosis may require open surgery for its cure. Indeed, untreated lesions can cause pain, infection or growing subcutaneous mass that can be confused with a soft tissue tumor. We report the clinical and radiological features of a 45-year old man with voluminous lumbar MLL initially misdiagnosed. We also reviewed the relevant English literature to summarize the diagnostic tools and the main therapeutic options.