Atypical Lipomatous Tumors of the Oral Cavity: A Report of 2 Cases

Abstract

Liposarcomas, first described by Virchow in 1857, are mesenchymal neoplasms arising from adipose tissue. The most common of all soft tissue sarcomas, liposarcomas account for approximately 20% of all soft tissue sarcomas. Liposarcomas may arise wherever adipose tissue is normally present, but the great majority occur in the retroperitoneum and deep soft tissues of the proximal aspects of the extremities. Head and neck liposarcomas are uncommon, constituting between 5% and 9% of all liposarcomas. Oral liposarcomas are even less common, comprising 0.3% of 5,435 liposarcomas studied from 1974 to 2000 at the Armed Forces Institute of Pathology. To date, there have been fewer than 90 reported cases of oral liposarcomas in the English language literature. Of these cases, the most common sites for occurrence are the cheek/buccal mucosa (38%) and tongue (33%), followed by the palate (7%) and the floor of the mouth (7%). The classification scheme for liposarcomas is somewhat controversial. Of the 2 existing classifications, by Stout et al and Enzinger et al, the latter is used by most investigators. Enzinger et al classified these tumors in 1962 into 4 main groups: well-differentiated, myxoid, round-cell, and pleomorphic. Well-differentiated and myxoid liposarcomas tend to recur locally, rarely metastasize, and have a higher 5-year survival rate as compared with the last 2 types. In 1979, Evans et al proposed a modification to this classification scheme as first suggested by Kindblom et al. Based upon a review of 30 cases of welldifferentiated liposarcomas, Evans et al noted that tumors found within superficial tissues only rarely recurred locally, none metastasized, and no patients died from disease. In contrast, tumors located within deep tissues had a high rate of aggressive local recurrence, and several patients died secondary to unresectable tumors. Thus, Evans et al proposed that welldifferentiated liposarcomas located within superficial tissues be distinctly classified as atypical lipomas or atypical lipomatous tumors (ALT). Additionally, histologically and morphologically identical tumors found within deep tissues would remain classified as well-differentiated liposarcomas. This new classification scheme has not been universally accepted. Some investigators believe that the term atypical lipomatous tumor is misleading because the recurrence rate of superficial lipomatous tumors is much higher than that of benign lipomatous tumors, and this confusion could lead to insufficient definitive treatment. Hadju et al prefer the term borderline adipose tissue neoplasm to highlight the high recurrence rate and need for wide local excision to prevent recurrence. However, in 2002 the World Health Organization (WHO) adopted the term atypical lipoma or atypical lipomatous tumor as valid terminology and is accepted and used by many investigators. In this article, we present an additional 2 cases of ALT of the tongue. Additionally, the clinical and histologic features, suggested treatment, and review of the literature relative to ALT of the tongue will be presented.