Lipoblastoma: computed tomographic and magnetic resonance imaging features correlate with tumor behavior and pathology.

Background: Lipoblastoma is a rare benign neoplasm of immature fat cells in children. Imaging appearances are frequently complex, sometimes simulating liposarcoma.

Objective: To characterize features of lipoblastoma on MRI and CT in comparison with recurrence risk.

Materials And Methods: We identified cases via retrospective review of histopathology-proven lipoblastoma cases in a large referral database and a pediatric medical center. Two radiologists scored CT and MRI on the basis of lesion features.

Results: We included a total of 56 children (32 boys and 24 girls) with a mean age of 2.6 years (range 0.1-13 years). Extremity lesions were most common (27%), followed by neck (19%), gluteal region (18%), chest (14%) and mesentery (14%). Children most commonly presented with painless masses (73%), followed by dyspnea (9%), distension (9%) and pain (7%). Non-adipose soft-tissue components were identified on CT and MRI in 78% of cases. Significant (moderate or marked) septations were noted in 59% and enhancement in 35%. Compartmental invasion was present in 43% of cases. Of paraspinal cases, 38% involved the neural foramina or central canal. Lesion complexity did not significantly correlate with age. Recurrence was observed in 9% of cases and was significantly correlated with compartmental invasion (correlation: 0.303, P=0.009) and septation complexity (correlation: 0.227, P=0.038) on initial imaging.

Conclusion: Although lipoblastoma is a fat-containing entity, many lesions demonstrate marked complexity and local infiltration that resemble liposarcoma, which is exceedingly rare in younger children. Compartmental invasion and thicker septations appear to confer greater risk of recurrence following resection.