Adhesion proteins, cellular morphology and fibrous components around the cell/extracellular-matrix interface in myxoid liposarcomas.

We examined the cell/extracellular-matrix interface in 13 myxoid liposarcomas by determining the distribution of collagen and reticular fibers in the myxoid matrix, the presence of adhesion proteins and the morphological features of the cytoplasmic border. Adhesion proteins (fibronectin, integrin alpha3) and the cytoplasmic border were examined by immunofluorescence and a differential interference-contrast image analysis respectively. A network of reticular fibers and collagen fibers was present in the myxoid matrix of 11 cases (85%) and 3 cases (23%) respectively. Tumor cells with dendritic cytoplasmic processes were observed in 8 cases (62%). Adhesion proteins were sparsely present in tumor cells and there was no correlation between those proteins and collagen fibers, reticular fibers or cytoplasmic processes. Collagen fibers, dense reticular fibers or well-developed cytoplasmic processes were more frequently observed in the cases of long-term-surviving patients than those with recently developed tumors or patients who died. All 3 cases positive for collagen fibers also contained both dense reticular fibers and cytoplasmic processes. Our findings suggest that the fibrous components in the myxoid matrix and the well-developed cytoplasmic processes may limit the invasiveness of malignant cells. This peculiar architecture may also explain the slowly progressive nature of myxoid liposarcomas.