Surgical Pathology Criteria

Lipoblastoma / Lipoblastomatosis

Differential Diagnosis

Lipoma Lipoblastoma / Lipoblastomatosis
Lacks primitive mesenchymal cells and lipoblasts Primitive mesenchymal cells and lipoblasts virtually always at least focally present
Unusual on extremities Frequent on extremities
Various chromosomal abnormalites but not involving 8q11-13 8q11-13 abnormalities
Occasional lobules of lipoblastomatosis may be virtually indistinguishable

Myxoid Liposarcoma Lipoblastoma / Lipoblastomatosis
Maturation if present, occurs towards periphery Maturation if present, occurs towards center of lobules
Rare <20, very rare <10 Very rare >20, rare >10
May have hypercellular areas Uniformly hypocellular
Virtually always deep May be superficial or deep
t(12;16) or t(12;22) Abnormalities involving 8q(11-13)

Lipoblastoma Hibernoma
Restricted to children at presentation Rare in children
Immature cells and lipoblasts Microvesicular brown fat
8q11-13 abnormalities 11q13 abnormalities

Lipoblastoma Chondroid Lipoma
Uniform population of lipoblasts Variable size of vacuolated cells
No chondroid matrix Chondroid matrix
Restricted to children Age range 14-75
Deletions of 8q(11-13) t(11;16)

Lipoblastoma Fat Necrosis
At least focal vascular myxoid stroma Lacks vascular myxoid stroma
Immature fat cells with vacuoles Foamy cytoplasm, few vacuoles
Uniform pattern Variable pattern from normal fat to necrotic fat to histiocytes

Lipoblastoma with Extramedullary Hematopoiesis Myelolipoma
Immature fat cells present No immature fat cells
Areas with vascular myxoid stroma Lacks vascular myxoid stroma
Usually under age 10, virtually always under 20 Usually over age 40

Lipoblastoma / Lipoblastomatosis Lipofibromatosis
Septa infrequently cellular Prominently cellular septa
Usually immature fat mixed with mature Mature fat
Fat cells may have multiple vacuoles Single fat vacuoles

Lipoblastomatosis Infantile Fibromatosis
At least focal plexiform capillaries No plexiform capillaries
Contains lipoblasts Mature fat cells only
Lobular pattern Infiltrative pattern

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