Lipoblastoma : Microscopic Features

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Microscopic Features: The lobules in lipoblastoma have a myxoid stroma that may show a plexiform vascular network. When prominent, these areas resemble myxoid liposarcoma. One must remember that myxoid liposarcomas are extremely rare in children under the age of 10 years.

Mast cells are commonly found in the stroma. Cytologic atypia is absent and mitotic activity is not increased. The appearance of diffuse lipoblastomatosis is similar to lipoblastoma. The lobular architecture is less pronounced. Skeletal muscle fibers may be admixed within the tumor.

Rare histologic findings in a lipoblastoma include fibroblastic proliferation with collagen deposition, chondroid metaplasia, extramedullary hematopoiesis, chronic inflammation, and multinucleated or floret cells.