We report a 31-year-old man who had parosteal lipoma inducing large pressure erosion of the right distal femur. A parosteal lipoma is a rare benign tumor composed of mature adipose tissue that is firmly adherent to the periosteum of the underlying bone. This tumor is known to be caused by bone change (cortical hyperostosis, bowing defomity, or pressure erosion). This case presented large pressure erosion of the underlying bone, which is the rarest pattern of bone change.
