Severe ulnar nerve palsy caused by synovial chondromatosis arising from the pisotriquetral joint: a case report and review of literature.

We report here the unique case of 60-year-old man with severe ulnar nerve palsy caused by synovial chondromatosis arising from the pisotriquetral joint. At operation, the tumor entrapped the ulnar nerve proximal to the Guyon canal so that it was severely paralyzed. The ulnar neurovascular bundle could be separated safely under the microscope. To our knowledge, this type of severe neuropathy has not been reported before. Although synovial chondromatosis associated with peripheral nerve neuropathy is extremely rare, we should be aware of the existence of this type of compression neuropathy in the upper limb.