Multimodal Imaging of Oncocytic Lipoadenoma Arising from the Parotid Deep Lobe with Medial Extension into the Parapharyngeal Space: A Case Report with Histopathologic Findings and Literature Review

초록

Background: Oncocytic lipoadenoma is an exceptionally rare benign fat-containing salivary gland tumor that most commonly arises in the parotid gland. Previous case reports have largely focused on histopathology with limited or single-modality imaging documentation; therefore, practical preoperative radiological characterization remains challenging. Case Presentation: A 46-year-old male presented with a 2-year history of a slowly enlarging right-sided parotid mass. Computed tomography and magnetic resonance imaging showed a well-circumscribed fat-containing mass with a discrete medially enhancing solid component, mild diffusion restriction and small cystic foci without aggressive features. Ultrasonography revealed a heterogeneously hypoechoic parotid mass; however, limited acoustic penetration hindered evaluation of the deep portion. A core-needle biopsy was inconclusive, and an atypical lipomatous tumor could not be excluded. Subsequent surgical excision confirmed an oncocytic lipoadenoma, a biphasic tumor comprising mature adipose tissue and cytokeratin 7-positive oncocytic epithelial nests. The patient has remained recurrence-free for 7 years after surgery. Conclusions: Fat-containing parotid tumors can be diagnostically challenging because imaging findings are often nonspecific, and biphasic lipoepithelial entities are rarely encountered. This case highlights that awareness of the pattern of macroscopic fat with a discrete enhancing non-fat component, interpreted alongside histopathological findings, may help narrow the differential diagnosis, guide management, and reduce diagnostic uncertainty.

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