The Use of Radiation Therapy in the Management of Selected Patients with Atypical Lipomas

Background and Objectives. Atypical lipomas are uncommon, slow-growing benign tumors. While surgery has been the primary treatment modality, we have managed some patients with radiation (RT) as a component of the treatment and have reported their outcomes in this study. Methods. A retrospective review of all cases of extremity and trunk atypical lipomas in The Sarcoma Database at the study institution was conducted. Results. Thirteen patients were identified. All patients underwent surgical resection at initial presentation and received pre- or postoperative radiation for subtotal resection ( ), local recurrence ( ), or progressive disease ( ). The median total radiation dose was 50？Gy. Median followup was 65.1 months. All patients treated with RT remained free of disease at the last followup. No grade 3 or higher late toxicity from radiation was observed. No cases of tumor dedifferentiation occurred. Conclusion. For recurrent or residual atypical lipomas, a combination of reexcision and RT can provide long-term local control with acceptable morbidity. For recurrent tumors, pre-op RT of 50？Gy appears to be an effective and well-tolerated management approach. 1. Introduction The term atypical lipoma was first introduced in 1974 [1] to describe lobulated, well-circumscribed, large lesions that are histologically characterized by mature adipocytes of varying size and scattered atypical stromal cells with hyperchromatic nuclei (Figure 1) [2, 3]. Atypical lipomas are slow-growing tumors that typically affect the extremities and trunk. In the absence of a dedifferentiated component, atypical lipomas do not metastasize and pattern of failure is predominantly local [3–11]. The primary treatment modality has been surgical resection, with reexcision for recurrent lesions. Figure 1: Histologic presentation of atypical lipoma. Atypical lipoma composed of mature fat and fibrous tissue with scattered, enlarged, hyperchromatic cells. The role and utility of preoperative or adjuvant radiation in management of these lesions is not well known. We have managed some patients with recurrent or subtotally resected tumors with radiation as a component of the treatment. In this study, we review the outcomes of thirteen patients with atypical lipoma treated with radiation therapy (RT) at the Massachusetts General Hospital during the years of 1995–2010. 2. Methods A retrospective review of all cases of atypical lipoma treated with radiation at the Massachusetts General Hospital was conducted. Patients were excluded if RT was completed after January 2010. Thirteen consecutively