LIPOSARCOMA OF THE ANTERIOR MEDIASTINUM AND THYMUS - A CLINICOPATHOLOGICAL STUDY OF 28 CASES

We studied 28 cases of anterior mediastinal liposarcoma occurring in 1 6 males and 12 females with a mean age of 43 years (range, 14-72). Pre senting symptoms included dyspnea (four cases) and chest pain (four ca ses), although 11 tumors were detected incidentally by routine chest r adiography. Seven cases were believed to be located within the thymus. Most (i.e., 25) of the cases were of low grade, with the well-differe ntiated lipoma-like or sclerosing subtypes constituting 60% and the my xoid subtype constituting 28%; the remaining 12% exhibited mixed featu res. Three cases were pleomorphic type. Several low-grade tumors exhib ited widespread, dense aggregates of mature-appearing lymphocytes and plasma cells, which occasionally obscured the mesenchymal nature of th e neoplasm, suggesting instead a lymphoid neoplasm or a reactive fibro inflammatory condition. The three high-grade tumors showed combination s of pleomorphic and round cell patterns, with focal myxoid areas. Of the cases grossly arising within the thymus, only one showed extensive thymic tissue within the lesion (''thymoliposarcoma''); six others ex hibited residual thymus peripheral to the tumor. Clinical follow-up in 23 cases revealed recurrence in seven patients (31.8%), with a mean i nterval to recurrence of 3 years. Eight patients died (mean survival, 2.6 years), one postoperatively and three following a recurrence. Fift een patients were alive (mean survival, 2 years), four with recurrent tumor. The myxoid tumors had a somewhat more aggressive course than th e well-differentiated tumors. Metastases were not observed in any of t he patients.