A 57-year-old Caucasian right hand dominant man presented with a 10-year history of a progressively enlarging and mildly tender mass over the bony olecranon of his right elbow. He had initially noted the mass without any previous trauma or pain, and felt the mass was relatively stable in size. During one acute episode after a fall about three years prior to presentation, the mass had seemed to become larger and more bothersome, but was not investigated further. Over the past two years, the mass had been somewhat variable in size, but continued to enlarge slowly. More recently, it had also become mildly tender and particularly uncomfortable when the elbow was placed on a table or desk. He did not have a history of gout or inflammatory arthropathy.
No imaging studies were obtained. Our patient's family doctor made the diagnosis of chronic olecranon bursitis. Two corticosteroid injections were attempted without any change in symptoms. Eventually, a referral was made to an orthopedic elbow surgeon. The first examination by the surgeon revealed a vague mass over the olecranon, measuring approximately 3 × 3 cm. There were no skin changes, and no excessive warmth or erythema to suggest infection. A neurovascular examination demonstrated some decreased sensation to pinprick over the dorsal first web space of the affected hand, with full motor power in the distribution of all major nerves including the radial and posterior interosseous nerves. No other sensory deficits were identified.
Our patient chose to continue observing the mass. At a follow-up appointment about six months later, the decision was made to proceed with surgical treatment with excision of the olecranon bursa for presumed chronic aseptic olecranon bursitis. At that time, the sensory deficit in the hand had almost completely resolved. No further imaging or investigation were pursued.
At the time of surgery, a standard posterior approach to the olecranon bursa was employed. Upon dissection through the subcutaneous tissues, the olecranon bursa was identified but was found to be displaced proximally and superficially by an encapsulated mass extending from the fascia to the lateral side of his proximal dorsal ulna. The capsule was fibrous and easily separated from the subcutaneous tissue although it was inseparable from his dorsal forearm fascia. A yellow, uniform fatty mass was found to be protruding through a defect in his dorsal forearm fascia originating within the most proximal portion of the extensor group. There was no invasion of the local muscle tissue and his elbow capsule was intact and uninvolved.
Histopathological examination confirmed the diagnosis of a lipoma (Figure ) with myxoid change (Figure ) and no evidence of malignancy. Post-operative examination confirmed a normal neurovascular examination with no recurrence of paresthesia and normal power in all muscle groups in his upper extremity. Our patient maintained a full range of motion of his elbow and forearm.
High-power (200×) H&E stain of benign lipoma tissue from the surgical specimen. Typical adipocytes with no evidence of malignant change.
High-power (100×) H&E stain of myxoid degeneration within benign lipoma. Adipocytes (blue arrow) interspersed with deposition of mucin-like tissue (red arrow).