A Case of Atypical Lipomatous Tumor that Dedifferentiated with Second Recurrence after Additional Resection

Dedifferentiated liposarcoma is recognized as a type of liposarcoma that usually occurs concomitantly with the well-differentiated type. In this report, we discuss the case of a 65-year-old man who developed a dedifferentiated liposarcoma with second recurrence of an atypical lipomatous tumor. The patient first presented to us with an atypical lipomatous tumor of the right elbow for which he underwent a marginal resection. After five months, the patient experienced tumor recurrence for which he underwent another extended resection. Approximately 10 months following this surgery, the tumor recurred a second time for which he underwent another extended resection. Histopathological analysis of the second recurring tumor revealed a dedifferentiated liposarcoma. So far, two years following this resection, recurrence has not been observed. This is the first case of an atypical lipomatous tumor that dedifferentiated after the additional extended resection.