Lymphocyte-rich well-differentiated liposarcoma: report of nine cases.

Nine well-differentiated liposarcomas with foci simulating the appearance of malignant lymphoma and other lymphoid disorders are reported. Their clinical presentation and evolution were not significantly different from those of their conventional counterparts lacking a lymphoid infiltrate. Microscopically, these tumors were characterized by areas of ordinary well-differentiated liposarcoma, admixed with discrete nodules comprised of small germinal centers, and separated by an admixture of lymphocytes, spindled stromal cells, collagen, and blood vessels, in which highly atypical tumor cells were embedded. The differential diagnosis included Hodgkin's disease, Castleman's disease, and inflammatory pseudotumor. Immunohistochemical evaluation revealed a pre-dominance of T cells in the lymphocytic population. Molecular genetic studies revealed no evidence of clonal rearrangement of the T cell receptor gene, supporting the interpretation of these lymphocytes as reactive. Awareness of the existence of this variant of inflammatory liposarcoma should prevent its misinterpretation as a primary lymphoproliferative process.