Dedifferentiated Liposarcoma of the Pyriform Sinus

Abstract

Laryngeal and hypopharyngeal liposarcomas are extraordinarily infrequent tumors. To the best of our knowledge there are fewer than 40 well-documented cases re ported to date. Almost all of them are well-differentiated liposarcomas, with only 2 laryngeal-hypopharyngeal dedifferentiated liposarcomas. Dedifferentiated liposar coma is defined as a well-differentiated liposarcoma with areas of high-grade spindle cell nonlipogenic sarcoma. The well-differentiated areas may be of a lipoma like, sclerosing, or mixed type, and the dedifferentiated areas most frequently are of malignant fibrous hystiocytoma-like type. Despite its commonly pleomorphic his tology, dedifferentiated liposarcoma does not behave as aggressively as most pleo morphic sarcomas of adulthood; however, it has the capacity to metastasize, in contrast to its well-differentiated counterpart. We present a case of dedifferentiated liposarcoma arising in the pyriform sinus, an event only twice reported previously in the literature. Int J Surg Pathol 10(1):75-79, 2002