Liposarcoma

Liposarcoma (syn: myxoma lipomatodes maligna, myxoides liposarcoma) malignant tumor of adipose tissue, rarely developing in the subcutaneous tissue, chatting in the intermuscular fascia of the thighs with the subsequent germination of the subcutaneous fat layer. It never develops from the lipoma, metastasizes primarily to the lungs and liver.

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Pathomorphology of liposarcoma

Liposarcoma has a pronounced variability in the morphological structure, depending on the degree of differentiation of its constituent cellular elements. In the liposarcoma, the following cell types are distinguished: mucoid lipoblasts with spindle-shaped nuclei and small Sudanophil droplets in the cytoplasm (with a certain degree of differentiation), mucoid lipoblasts with bizarre nuclei and the absence of fatty droplets in the cytoplasm (with a high degree of anaplasia) located in the mucoid stroma, Lipoblast with spindle-shaped nuclei and grossly vacuolized cytoplasm; well-differentiated cells with single large vacuoles and spindle-shaped nuclei located eccentrically; mature fat cells; cells with rounded, centrally located nuclei and multiple vacuoles in the cytoplasm; giant cells with bizarre nuclei.

Depending on the predominance of this or that type of cells, WF Lever and G. Schanmburg-Lever (1983) distinguish four types of liposarcoma: highly differentiated, myxoid circular and pleomorphic. Relatively high-differentiated liposarcoma resembles a lipoma consisting of cells of different sizes with one vacuole and hyperchromic nuclei. Between them are cells with large, hyperchromic and pleomorphic nuclei.

Mixed liposarcoma is divided into high- and low-grade types. In myxoid liposarcoma type 1, there are few myxoid cells, lipoblasts with spindle-shaped nuclei and small Sudanophil drops in the cytoplasm predominate, highly differentiated fat cells and spindle-shaped lipoblasts with roughly vacuolar cytoplasm. Myxoid liposarcoma of the second type is dominated by myxoid lipoblasts with bizarre nuclei and a small amount of sudanophilic substance. The stroma is scant, mucoid in appearance, which gives this type of liposarcoma a resemblance to a myxosarcoma or undifferentiated fibrosarcoma.

Round-celled liposarcoma is characterized by the presence of densely located, rounded or oval cells with one vacuoles (peristone prominent cells) and lipoblasts with multiple vacuoles. The nuclei are large, hyperchromic and atypical, often in a state of mitosis.

Pleomorphic liposarcoma consists mostly of pleomorphic, giant multivacuolar lipoblasts with one or more (several) hyperchromic nuclei. Among them are small, polygonal, rounded or fusiform lipoblasts. In some cases, the presence of a large number of vacuoles in lipoblasts gives them an atypical appearance and resemblance to the mulberry. This gives grounds for attributing this kind of liposarcoma to a malignant hibernoma.

How is liposarcoma diagnosed?

The diagnosis of liposarcoma is based on the presence of lipids in the tumor, however, in the case of pleomorphic and round-cell types, the detection of intracellular hyaluronidazolabile mucoid inclusions that are detected by staining with alcian blue is of diagnostic importance due to the absence of a sudanophilic substance. Liposarcoma also contains hyaluronic acid, like embryonic adipose tissue, and quite often glycogen. Differentiated liposarcoma from immature rhabdomyosarcoma and systemic multicentric myoblastosis, which affects subcutaneous adipose tissue and internal organs.