Oral Lipoma or Atypical Tumor? The Importance of Complementary Diagnostic Studies in Oral Medicine

Abstract

Lipomas rarely affect the oral cavity, typically presenting as a slow-growing, painless submucosal mass. Histological variants featuring spindle cells, pleomorphism or myxoid change can mimic an atypical lipomatous tumor, a well-differentiated liposarcoma, or a spindle cell lipoma, creating diagnostic uncertainty. We report the case of a 61-year-old woman with a one-month history of painful swelling of the right buccal mucosa, suggestive of a lipoma. Imaging demonstrated a well-circumscribed, non-encapsulated, lobulated lesion of fat density measuring 2.4 cm. The lesion was excised by intraoral approach, preserving the parotid duct. Histopathology showed a lipomatous neoplasm with adipocytes of variable size, spindle cells without atypia, and myxoid stroma. Immunohistochemistry showed a partially discordant pattern, with cyclin-dependent kinase 4 positivity but no murine double minute 2 expression, prompting molecular testing. Fluorescence in situ hybridization excluded retinoblastoma gene loss and murine double minute 2/cyclin-dependent kinase 4 amplification, confirming a benign lipoma with myxoid change by exclusion. Recovery was favorable, with transient paresthesia and limited upper lip mobility resolving within three months, and no recurrence at follow-up. This case illustrates how integrating clinical, imaging, histopathological, immunohistochemical and molecular findings enables a safe, definitive diagnosis of atypical oral lipomatous lesions.