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2 year old male with right shoulder mass.
Lipoblastoma is a benign adipocytic tumour which most commonly presents before age 3. Microscopically, it is a well-circumscribed neoplasm comprised of lobules of adipose tissue separated by a delicate fibrovascular network. The lobules have mature adipocytes and the peripheral aspects have increased densities of lipoblasts, with indented nuclei and some hyperchromatism. The vascular network is prominent, particularly at the periphery of the lobules, where a small branching capillary-like network is present. There is prominent myxoid degeneration. Mitotic figures are not seen. Myxoid liposarcoma may be considered in the differential diagnosis; however, it is rare in young children and has a characteristic translocation, t(12;16), which is absent in lipoblastoma.