Lipoma of the oral and maxillofacial region: Site and subclassification of 125 cases

Objective. Lipomas and lipoma variants are common soft tissue tumors, but occur infrequently in the oral and maxillofacial region. In this study, we reviewed 125 lipomas in specific oral and maxillofacial locations. We wanted to examine and compare the clinicopathologic features of these tumors. Study design. The records from the Oral and Maxillofacial Pathology Registry of the Armed Forces Institute of Pathology from 1970 to the present were searched for cases coded as "lipoma." This study included 125 cases based on location within the oral and maxillofacial region, benign histology, and available clinical information. Subcutaneous and intraosseous lipomas were excluded. The tumors were classified according to the most recent World Heath Organization classification for soft tissue tumors. Results. Of 125 lipomas, 91 tumors occurred in males, 33 in female patients, and 1 of unknown gender. The mean age was 51.9 years, range 9-92 years. Four tumors occurred in pediatric patients (age <18 years). Specific anatomic sites within the oral and maxillofacial region included the parotid region (n = 30); buccal mucosa (n = 29); lip (n = 21); submandibular region (n = 17); tongue (n = 15); palate (n = 6); floor of mouth (n = 5); and vestibule (n = 2). The mean size of tumors was 2.2 centimeters, range 0.5 to 8.0 centimeters. The mean duration of the tumors prior to excision was 3.2 years, range 6 weeks to 15 years. Most patients presented with an asymptomatic, circumscribed mass. Grossly, most tumors were described as pink and smooth, occasionally mucoid. Histologically, the tumors were subclassified as classic lipomas (n = 62); spindle cell/pleomorphic lipomas (n = 59); fibrolipoma (n = 2), and chondroid lipoma (n = 2). Fourteen tumors exhibited secondary changes, such as fat necrosis, atrophy, and prominent hyalinization; 23 tumors were histologically confirmed to be intramuscular. Conclusions. Lipomas of the oral and maxillofacial region occur most commonly in adult males in the parotid region, followed closely by the buccal mucosa. These tumors are uncommon in children. Interestingly, spindle cell lipomas are common in this region and comprise the majority of our parotid and lip tumors. Angiolipomas were absent in this anatomic region in this study. Secondary changes and atrophy should not be confused with the malignant histologic features of a liposarcoma.