A 2-year-old boy was presented with symptoms of chest infection. The chest radiograph showed a large mediastinal mass, which led to further investigations including biopsy of the tumour. Histopathological analysis revealed a diagnosis of lipoblastoma. We highlight the imaging appearance of the lesion. Although histopathological analysis is required for the confirmation of the diagnosis, cross-sectional imaging is useful in evaluating the extent of the tumour for surgical planning.