Presentation
History of ground-level fall 10 months ago presenting with right leg pain and refusal to bear weight.
Patient Data
1. A fairly well-circumscribed 2cm sized lucent septated appearing lesion with a sclerotic rim is seen at the medial and posterior aspect of the distal femoral metaphysis. Given history of benign lesion for over 10 months differential considerations include distal femoral cortical irregularities versus nonossifying fibromas versus an indolent infection among other differentials. No discrete soft tissue mass to suggest a malignant process. No knee joint effusion.
2. No other discrete focal osseous lesion. No discrete periostitis. No abnormal soft tissue calcifications.
3. The bone density is normal. The knee joint spaces are well preserved.
Case Discussion
Since differentials for common bone lesions for pediatric patients less than 10 years old include simple bone cysts, Ewing sarcoma, osteosarcoma, infection, and eosinophilic granuloma, clinical correlation is essential. The malignant potential of osteolytic lesion can be determined by the zone of transition. A narrow and sharp zone of transition suggests a benign lesion.
This case was submitted with supervision and input from:
Soni C. Chawla, M.D.
Health Sciences Clinical Professor,
Department of Radiological Sciences,
David Geffen School of Medicine at UCLA.
Attending Pediatric Radiologist,
Olive View - UCLA Medical Center.