Intramuscular myxoid lipoma in the proximal forearm presenting as an olecranon mass with superficial radial nerve palsy: a case report

We discuss the case of a 57-year-old Caucasian man who presented with a tender, posterior elbow mass initially diagnosed as chronic olecranon bursitis. A minor sensory disturbance in the distribution of the superficial radial nerve was initially thought to be unrelated, but was likely caused by mass effect from the lipoma. No pre-operative advanced imaging was obtained because the diagnosis was felt to have already been made. At the time of surgery, a fatty mass originating in the volar forearm muscles was found to have breached the dorsal forearm fascia and displaced the olecranon bursa. Tissue diagnosis was made by histopathology as a myxoid lipoma with no aggressive features. Post-operative recovery was uneventful.We present a case of an unusual elbow mass presenting with symptoms consistent with chronic olecranon bursitis, a relatively common condition. The only unexplained pre-operative finding was the non-specific finding of a transient superficial radial nerve deficit. We remind clinicians to be cautious when diagnosing soft tissue masses in the extremities when unexplained physical findings are present.Nerve entrapment at the elbow has been described affecting the median, ulnar and radial nerves as well as their divisions. Symptoms are variable and depend on the location of the lesion and cause of entrapment. Over the past three decades, radial tunnel syndrome has come to be recognized as a true clinical entity and surgical treatment has become more common [1]. One of the rare causes of compression is a mass lesion such as a parosteal lipoma which may affect either the radial nerve [2], the superficial sensory radial nerve [3] or the posterior interosseous nerve [4]. In these cases, the diagnosis is often delayed and may be confused with lateral epicondylitis or other more common elbow pathologies [5].Olecranon bursitis is a more common elbow pathology in the general population which may be either acute or chronic, and in the acute setting may be septic or a