Adamantinoma of the long bones is a rare primary malignant bone tumor accounting for less than 1% of all primary malignant bone tumors. Most typical imaging findings include heterogeneous osteolytic cortical lesions showing multiple sharply circumscribed lucent zones of various sizes with sclerotic bone surroundings, interspersing between, and extending above and below the lucent zones by the thinning and bulging cortex. Advanced or recurrent lesions may be associated with destruction of the cortex and soft tissue extension. In this article, the authors present a case report of a patient with a distal tibia adamantinoma mimicking a benign cystic lesion.