Solitary epiphyseal enchondromas.

BACKGROUND

Enchondromas originating in the epiphyses of long bones are rare. The purpose of the present study was to evaluate the prevalence as well as the radiographic and clinical characteristics of epiphyseal enchondromas among patients who had been referred to the Armed Forces Institute of Pathology and Walter Reed Army Medical Center.

METHODS

We performed a retrospective review of 761 patients who had been referred to our two institutions over an approximately fifty-five-year period and who received a final diagnosis of enchondroma. All lesions had been biopsied, and the pathological diagnosis had been confirmed. Lesions of the hands, feet, or axial skeleton (253 patients) as well as lesions that appeared to originate in the metaphysis or diaphysis (475 patients) were excluded. Only enchondromas of the long bones that originated in the epiphysis were analyzed. The study group included thirty-three patients (twenty male patients and thirteen female patients) with a mean age of 26.7 years, including eleven patients with open physes. We performed additional descriptive analyses with regard to patient age, gender, lesion location, clinical presentation, and treatment as well as an extensive radiographic analysis.

RESULTS

The most common locations were the proximal part of the humerus (ten lesions; 30%) and the distal part of the femur (six lesions; 18%). The most common presenting symptom was pain (twenty-three patients). Radiographic analysis demonstrated extensive matrix mineralization in association with twenty-three lesions. Twenty-eight of the thirty-three lesions were geographically well defined; of these, twenty-one had sclerotic borders, and seven did not. Although all lesions were centered and were predominantly located within the epiphysis, twenty of the thirty-three lesions demonstrated radiographic evidence of metaphyseal extension, including four of the eleven lesions in patients with open physes. Twenty-four lesions extended into the subchondral bone. The mean size of the thirty-three enchondromas in greatest radiographic dimension was 2.7 cm (range, 1.1 to 4.9 cm). Twenty-six of the thirty-three lesions were amenable to surgical treatment with curettage with or without bone-grafting, with only one recurrence. With the limited follow-up available, no lesion underwent sarcomatous degeneration.

CONCLUSIONS

Epiphyseal enchondromas are rare lesions. Although their biologic behavior appears to mirror that of conventional metaphyseal enchondromas, their proximity to the joint space may lead to more frequent painful symptoms, a propensity for physeal involvement, and the need for earlier definitive surgical intervention.