Rotator cuff impingement due to enchondroma of the acromion.

We report the case of a patient with a long standing clinical history of subacromial impingement, in which plain radiographs and CT-scan revealed a well-circumscribed lucent lesion expanding the undersurface of the acromion. MRI showed the subacromial fat to be completely obliterated and the infraspinatus tendon deformed due to compression by a mass localised at the acromion. The acromial lesion was curetted, and histopathologic analysis was consistent with the diagnosis of enchondroma. Tumours located in the coracoacromial arch have been very rarely reported as a cause of subacromial impingement. To the best of our knowledge, this is the first description of subacromial impingement secondary to acromial enchondroma.