Knee Deep in Discovery: Incidental Contralateral Non-Ossifying Fibroma in an Adolescent Male - A Case Report

Bone tumours are rare neoplastic disorders, with their infrequent malignant counterparts posing significant risks to child and adolescent morbidity and mortality. Thus, appropriate recognition and distinction of such lesions remain pivotal. In the South African context, where local epidemiological data remain limited, this case enhances clinical awareness and highlights the importance of specialist referral and ongoing surveillance.

We report a case of an 18-year-old scholar in whom an X-ray evaluation for an old sports injury to the left knee revealed an incidental benign bone tumour of the contralateral distal femur. Radiographs were obtained to assess the affected knee, and a control X-ray of the opposite limb unexpectedly demonstrated a distal femoral lesion, prompting further orthopaedic evaluation. Radiological findings suggested a benign bone tumour, and based on imaging characteristics, multiple non-ossifying fibromas were diagnosed. Given the absence of symptoms and radiological signs of aggressiveness, a conservative management plan with serial imaging was adopted.

This case underscores the value of contralateral imaging and vigilance in distinguishing benign from malignant lesions in adolescents.