Cytology Diagnosis of Oncocytic Lipoadenoma of the Parotid Gland: A Rare Case Report

Oncocytic lipoadenoma is a rare benign salivary gland neoplasm characterized by a biphasic proliferation of oncocytes and mature adipocytes. It predominantly affects the parotid gland and may pose a diagnostic challenge on cytology. A 60-year-old woman presented with a gradually enlarging, painless left preauricular swelling for one year. Ultrasonography revealed a heterogeneous lesion involving the superficial lobe of the parotid gland. Fine-needle aspiration cytology showed benign oncocytes admixed with mature adipocytic fragments and benign salivary acini, and the lesion was categorized as a benign oncocytic neoplasm. Superficial parotidectomy was subsequently performed. Histopathological examination demonstrated a well-circumscribed biphasic tumour: it was composed of bland oncocytes arranged in nests and lobules that were intimately admixed with mature adipocytes, without atypia, increased mitotic activity or necrosis. A diagnosis of oncocytic lipoadenoma was rendered. Recognition of this rare entity is important to avoid diagnostic errors and unnecessary aggressive management. Complete excision is curative.