The carpal boss: review of diagnosis and treatment.

It is not uncommon to find a protruding mass at the dorsum of the wrist. The carpal boss is a commonly overlooked condition of unclear etiology. Minor trauma and persisting os styloideum are among the suspected causes of the condition. Long-standing carpal boss can lead to osteoarthritic damage in some patients. Many diagnostic tools, such as a "carpal boss view" radiographic study or a technetium bone scan, are available to help differentiate carpal boss from other, more common, masses of the dorsal aspect of wrist. For years, excision of the mass has been a commonly described treatment, because conservative treatment does not always give relief of symptoms. However, the benefits of wide excision must be balanced by the risks of instability at the involved joints, leading to persistent, and potentially worsened, symptoms.