External surface of (benign) lipoma. The bright yellow color is typical of fat. Note the lobulated appearance, which is also typical of this lesion. This particular tumor arose in the subcutaneous fat (note the small strip of skin denoted by the black arrows).
Subcutaneous lipoma
Conventional Lipoma
Except for the circumscription, the appearance is indistinguishable from that of normal fat. lipomas consist of bright yellow fat separated by fine fibrous trabeculae.
The entire lesion is composed of typical large adipocytes
Subcutaneous lipomaPhotograph of sectioned gross specimen reveals the solid but gelatinous myxoid liposarcoma.
Myxoid liposarcoma thigh
Well demarcated lipoma-like tumor in the mesocolon. Liposarcomas are generally large tumors
Liposarcoma of mesocolon
Lipoblast: relatively specific for liposarc
These are relatively specific for liposarcoma; the cell contains multiple cytoplasmic lipid vacuoles that scallop the nucleus.Adult-appearing fat cells and more primitive cells, with lipid vacuoles (lipoblasts) are scattered in abundant myxoid matrix with compressed & branched capillaries
Myxoid liposarcoma thigh
The cell nuclei of Lipoblasts show, in contrast to mature fat cells much larger nuclei with Atypia. They are typical, but not specific for the liposarcoma.
Myxoid liposarcoma signet ring lipoblasts