Extradigital glomus tumor as a cause of knee pain.

Although there exists much debate in the dermatohistopathologic literature about the exact characterization of the glomus tumor, this case illustrates what should be considered the sine qua non indications of clinically significant glomus tumors, i.e., exquisite pain and complete relief of pain with surgical excision. One should not, therefore, limit the inclusion of glomus tumors to the differential diagnosis of severe localized pain only in the upper extremity.