Intraosseous Lipoma: 18 Years of Experience at a Single Institution.

Background: Intraosseous lipoma is a very rare lesion that constitutes no more than 0.1% of all bone tumors. We analyzed 21 cases of intraosseous lipoma at a single institution for clinical and radiographic characteristics.

Methods: A retrospective study was performed on 21 pathologically confirmed intraosseous lipomas treated in our hospital from 2000 to 2017. Simple X-ray and magnetic resonance imaging findings and medical records were reviewed. Patients' age, sex, and clinical symptoms were investigated. From the radiographic images, the site of the lesion, calcification, bony expansion, and stage of the lesion were evaluated. Correlations between the degree of involution and clinical symptoms were analyzed.

Results: The mean age of patients was 50 years (range, 20 to 67 years), and there were 13 males and eight females. The mean lesion size was 6.1 cm (range, 2.5 to 13.6 cm). The most common anatomical site of the lesion was the femur (seven cases), and three cases occurred in flat bones such as the ilium and scapula. Visual analogue scale score for pain was 3 to 6 in 15 patients. There were no complaints of functional limitation. There was no correlation between the degree of degeneration and clinical symptoms ( = 1.000). Curettage was performed as a surgical treatment in 20 patients, and bone graft was performed using a bone chip. Excision was performed in one patient. Pain was resolved in seven of 11 patients with a complaint of preoperative pain; intermittent pain remained in four cases. There was no local recurrence or malignant change during the follow-up.

Conclusions: There was no correlation between the degree of degeneration and clinical symptoms. Pain was the most common clinical symptom, but it was rarely accompanied by functional limitation. However, it is important to distinguish it from other pain-inducing disorders. The incidence of intraosseous lipomas is low, and detection based on various imaging findings can be difficult. Clear understanding of the radiographic findings and symptoms of intraosseous lipoma is helpful for diagnosis and differentiation.