Enchondroma with secondary aneurysmal bone cyst.

Area of Science:

• Orthopedic Surgery
• Pediatric Oncology
• Radiology

Background:

• Enchondromas are common benign bone tumors, typically found in the hands and feet.
• Proximal femur enchondromas are rare, and complex cystic changes are even less common.
• Aneurysmal bone cysts (ABCs) can be primary or secondary to other bone pathologies.

Observation:

• A 13-year-old male presented with an enchondroma exhibiting complex cystic changes in the proximal femur.
• Imaging revealed features suggestive of secondary aneurysmal bone cyst formation within the enchondroma.
• This presentation is unusual for a typical enchondroma.

Findings:

• The enchondroma demonstrated significant cystic degeneration, mimicking a more aggressive lesion.
• Histopathological examination confirmed the enchondroma with features of a secondary aneurysmal bone cyst.
• The combination of enchondroma and secondary ABC in the proximal femur is a rare finding.

Implications:

• This case underscores the importance of considering secondary aneurysmal bone cysts in the differential diagnosis of bone lesions, even in benign tumors like enchondromas.
• Accurate diagnosis is crucial for appropriate management and to avoid unnecessary aggressive treatment.
• Radiologists and orthopedic surgeons should be aware of this rare presentation to ensure correct patient management.