Adamantinoma of the Forearm: A Chronologic Presentation of a Slow-Growing Malignancy

The purpose of this report is to present a unique case of an uncommon tumor. Adamantinomas are inherently rare, low-grade malignant primary bone tumors that almost always involve the tibia. Although cases have been reported of these tumors involving the long bones of the upper extremity, we present an instance in which both bones of the forearm were affected with documented radiographic changes over a 7-year span. Surgical management is the mainstay of treatment for these tumors and usually requires limb reconstruction following resection. We also present an interesting reconstruction option for upper extremity limb salvage following surgical resection of these tumors. Adamantinomas are slow-growing, lowgrade malignant tumors usually found in the long bones. These tumors were first described in 1900. In 1913, Fischer coined the term “adamantinoma.”1 These tumors are uncommon, representing less than 1% of all malignant bone tumors.2 They are characterized as affecting the tibia in 80%–90% of cases and usually occur in patients in the second and third decades of life.3 Although adamantinomas show a predilection for involvement of the tibia, other skeletal sites have been reported, including the femur, radius, and ulna.4 Because of their malignant characteristics, adamantinomas of the long bones are usually treated with wide resection and reconstruction. Surveillance for distant recurrence when treating these tumors is mandatory as metastases are observed in 10%–30% of cases. Reports of involvement of the radius or ulna are limited to fewer than 10 cases, and we are unaware of any cases with simultaneous involvement of the radius and ulna. We report a unique case of an upper extremity adamantinoma ultimately affecting both the radius and ulna after a long period of preoperative observation. Treatment, therefore, included a wide resection of both the proximal radius and ulna and a subsequent reconstruction of the proximal ulna and ulnohumeral joint using an allograft-prosthesis composite. The aspects of this case—including its unique location, histopathology, and reconstruction using a total elbow arthroplasty-allograft composite—are discussed in the following sections.