Introduction: Osgood-Schlatter disease (OSD) is a traction apophysitis of the tibial tubercle and a common cause of anterior knee pain in growing adolescents. A variety of benign neoplasms can also cause bony prominence over the tibial tubercle in adolescents that might clinically imitate OSD. Therefore, the differential diagnosis of tumours mimicking OSD is critical and considered the primary goal of this study.
Methods: Eleven patients who were referred to our orthopaedic oncology department with clinical suspicions of OSD and obscure radiographic presentation were identified. The final diagnosis was OSD in three cases. The demographic, clinical, and radiologic characteristics of the remaining eight patients in whom a tumour mimicked OSD were evaluated. The diagnosis was confirmed by pathologic examination.
Results: The final diagnosis was periosteal chondroma in four cases, osteochondroma in three cases, and dysplasia epiphysealis hemimelica (DEH) in one case. The average age of the patients was 10.5 ± 3.1 years. In the majority of patients (62.5%), the lesion was painless. The mean size of the bump was 6.5 ± 1.2 cm2. In patients with a painful knee, the pain was constant and activity-independent. At history taking, the pain and bump size were progressive.
Conclusion: Lack of pain, progressive pain and bump, activity-independent pain, a bump size larger than 5 cm2 at presentation, and age fewer than ten years could be considered in favour of tumours and against OSD.
Keywords: Clinical mimicking; Differential diagnosis; Dysplasia epiphysealis hemimelica; Osgood-Schlatter disease; Osteochondroma; Periosteal chondroma.