Unicameral bone cyst with epiphyseal involvement: clinicoanatomic analysis

Area of Science:

• Orthopedic Surgery
• Pediatric Orthopedics
• Skeletal Biology

Background:

• Unicameral bone cysts (UBCs) typically occur in the metaphysis of long bones.
• Epiphyseal involvement of UBCs is uncommon, presenting a unique clinical and radiographic challenge.
• This study investigates the characteristics and treatment outcomes of epiphyseal UBCs.

Observation:

• Seven cases from literature and one new case of epiphyseal UBCs were analyzed.
• Patients averaged 20.1 years old, with lesions primarily in the proximal femur, humerus, and tibia.
• Radiographic analysis revealed characteristic epiphyseal and metaphyseal involvement.

Findings:

• Epiphyseal UBCs demonstrated a less aggressive biological behavior and a more favorable prognosis compared to metaphyseal UBCs.
• Curettage, with or without bone grafting, achieved a high success rate with 0% recurrence and no late complications.
• The first successful treatment of this variant using methylprednisolone acetate is reported.

Implications:

• Epiphyseal UBCs present diagnostic difficulties due to their atypical age and location but have a favorable prognosis.
• Aspiration and intralesional methylprednisolone acetate are recommended as initial management.
• The potential for epiphyseal reossification may contribute to the better prognosis of these lesions.