Atypical and malignant lipomatous lesions of the head and neck.

Although liposarcoma is the second most common soft-tissue sarcoma in adults, the incidence of liposarcoma of the head and neck is low. There are only 83 reported cases of head and neck liposarcoma. We report four cases of atypical and malignant lipomatous lesions of the head and neck and discuss their histologic classification and treatment implications. The histologic nature of liposarcoma is correlated clinically with treatment outcome. Recently, many authors have adopted the term atypical lipoma to describe well-differentiated lipomatous lesions in superficial extremity locations because of their tendency toward local recurrence only, without metastases or patient mortality. Although we accept the classification atypical lipoma for superficial, well-differentiated lesions, we believe that histologically similar lesions in nonsuperficial locations in the head and neck are best designated "well-differentiated liposarcoma."