- A low-grade malignant tumor of long bones (predominantly tibia) marked by a proliferation of nests of basaloid cells with palisading at the periphery.
- A rare, slow-growing but locally aggressive tumor; its histogenesis remains controversial. Approximately 200 cases have been reported since it was first described in 1913. The tumor occurs almost exclusively in the long bones; tumors in the tibia account for more than 80% of cases. The diaphysial region is the area most commonly affected. The histiologic features of adamantinomas have many variations that are present not only among patients but also among different areas of the same tumor. Metastases occur in approximately 15–20% of patients and typically appear in the lungs and local lymph nodes.