Dedifferentiated liposarcoma of the pyriform sinus

The authors presented a second reported case of dedifferentiated liposarcoma of the pyriform sinus in a 50-year old male, with a history of heavy smoking, airway obstruction and dysphagia. A computed tomography (CT) of the neck and thorax revealed a retroesophageal lobulated heterogenous mass. A laryngoscopic examination disclosed sessile polypoid mass in the right pyriform sinus. Microscopically, the neoplasm consisted of areas of well-differentiated liposarcoma and a non-lipogenic component (dedifferentiated component). These two parts were co-mingled, giving a mosaic pattern. Well-differentiated liposarcoma was characterized by adipocytes with a great variation in size, and multivacuolated lipoblasts. Immunohistochemical studies showed positive reactivity with vimentin and smooth muscle actin in non-lipogenic component. This neoplasm shows histological and immunohistochemical features of dedifferentiated liposarcoma with myogenic differentiation.