A Large Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma of Buccal Mucosa: Report of A Rare Case

Abstract

Abstract Introduction/Objective Liposarcoma is not common in the head and neck, and extremely rare in the oral cavity: 7% occur in the head and neck and 0.3% in the oral cavity. We report an atypical lipomatous tumor/well-differentiated liposarcoma (ATL/WDL) of the buccal mucosa with recurrence. Methods/Case Report A 66-year-old female presented with a right facial mass that had been present for over 10 years and resected 6 times as lipoma in her home country. The mass had grown since the last resection two years ago. Computerized tomography of neck soft tissue displayed a heterogeneous 11 cm mass with fat density in the right buccal mucosal spaces, and a 4.8 cm connecting solid nodule in the right pharyngeal mucosal space. Complete resection of the mass/nodule was performed. Grossly, the specimen consisted of two nodular masses (separately cut during operation), 13.1 cm and 7 cm, respectively. The cut surfaces of the masses revealed yellow fatty tissue with focal fleshy areas corresponding to the nodule with solid density by imagining. Microscopically, the squamous mucosa had a lipomatous tumor composed of sheets of well-differentiated adipocytes that infiltrated the underlying and surrounding skeletal muscle and connective tissue. Upon extensive sampling, scattered lipoblasts were found in relatively cellular areas. The nonlipogenic stromal cells with nuclear pleomorphism were seen in the fibrous/solid areas. No mitosis or necrosis was identified. MDM2 amplification was detected by fluorescent in situ hybridization (FISH). These findings support the diagnosis of recurrent ATL/WDL. Results (if a Case Study enter NA) NA Conclusion We demonstrate the histological features of a large atypical lipomatous tumor/well-differentiated liposarcoma of buccal mucosa. Extensive sampling of the specimen to identify the lipoblasts and atypical stromal cells, and MDM2 FISH study on suspicious cases are the keys to achieve accurate diagnosis. The high recurrence rate of this entity in the head & neck region exhibited in this case warrants the need of long-term follow-up.