A 17-YEAR-OLD boy was seen with a slowly enlarging, painful mass over the anterior aspect of his left tibia. The lesion was first noticed approximately 3 to 4 years ago, at which time it was small.
Results of a physical examination revealed a mass, 4 × 3 cm, overlying the distal aspect of the diaphysealmetaphyseal junction. There was no history of trauma to this site. The patient had full range of motion of his ankle and knee. He had no neurovascular abnormalitites and no palpable lymphadenopathy. The white blood cell count and sedimentation rate results were within normal limits. Further diagnostic evaluation, including radiographic studies (Figure 1), computed tomographic scan (Figure 2), and incisional biopsy (Figure 3 and Figure 4), was performed.
Diagnosis and Discussion
A damantinoma is a rare, slow-growing, low-grade malignant tumor that accounts for approximately 0.1% to 0.5 % of all malignant bone tumors.1,2 Its behavior