Non-Ossifying Fibromas: A 2025 Review

Abstract

In this comprehensive review, we explore the full spectrum of the most common incidentally found bone lesions in children and adolescents. Non-ossifying fibromas (NOFs) are benign, self-limiting bone lesions that represent a significant proportion of skeletal abnormalities in this population. Beginning with their first description by Sontag and Pyle and the subsequent histological characterization by Jaffe and Lichtenstein, we trace the historical evolution of understanding NOFs, including early theories on etiology, while outlining key epidemiologic, histopathologic, and advanced imaging findings. Furthermore, we discuss diagnostic criteria, management strategies, and emerging molecular insights for NOFs, emphasizing their clinical significance. By integrating historical perspectives, current diagnostic protocols, and emerging discoveries, this paper seeks to assist clinicians in optimizing diagnostic and treatment protocols to prevent unnecessary interventions through a comprehensive understanding of NOFs.

Keywords: Pediatric Orthopedics; benign bone lesion; non-ossifying fibroma.

Figure 1

Serial radiographs demonstrating the characteristic migration pattern of NOF away from the growth plate in a 9-year-old girl over 6 months (a,b). Note the eccentric location, sclerotic rim, and “bubbly” appearance that distinguish it from other lytic lesions. Image (c) demonstrates the major axis of the non-ossifying fibroma with an imaginary line (dashed arrow) pointing toward the gastrocnemius insertion (white circle), which is a typical migration pattern for NOFs.

Figure 2

Evolution through Ritschl stages (a) An 8-year-old girl at the first presentation. AP radiograph showing a lytic lesion of the left distal fibula in stage A. (b) Two years later, the lesion was polycyclic in shape with sclerotic borders (stage B). (c) At the age of 12 years, there was evidence of ossification beginning at the diaphysis, representing a stage C lesion.

Figure 3

Axial computed tomography slices demonstrating the “Pac-Man Sign” in a 13-year-old boy with a pathologic fracture through a distal tibia NOF. The characteristic shape is highlighted in yellow. The “Pac-Man Sign” is a highly specific (95%) predictor of pathologic fracture, and when present with other high-risk features, prophylactic surgical intervention should be considered.

Figure 4

Key histologic differentiators. Gross specimen (a) of a non-ossifying fibroma which has been curetted out of a patient. Representative histopathology showing multi-nucleated giant cells (b) and hemosiderin (c), with both examples demonstrating a characteristic whorled stromal pattern.

Figure 5

Surgical management of a symptomatic NOF. Pre-operative AP (a) and lateral (b) radiographs of a 17-year-old boy with a large, symptomatic left distal tibia NOF. Intra-operative fluoroscopy (c) demonstrating an AP radiograph with a curette in place. Post-operative lateral radiograph (d) demonstrating bone grafting in place.