A non-ossifying fibroma is a benign (non-cancerous) bone growth that usually occurs in children and adolescents. It is a collection of fibrous tissue that can form in the bone. These growths are generally found in the long bones, like the legs. Most of the time, non-ossifying fibromas don’t cause any problems and often go away on their own as the child grows. They are usually discovered incidentally during X-rays taken for other reasons. Surgical management may be recommended if the lesion is large enough to pose a risk for fracture.

An atypical lipomatous tumor is a type of fatty tumor that can grow in the soft tissues of the body, like muscles or fat. While it’s not cancerous, it has some unusual features that make it more concerning than a regular lipoma. These tumors can grow quite large and may need to be removed surgically. They have a higher chance of coming back after surgical removal (local recurrence) in comparison to lipomas and require monitoring following surgical treatment. Accurate diagnosis is imperative to ensure appropriate management of the tumor.