Malignant Transformation of Parotid Gland Non-sebaceous Lymphadenoma: Case Report and Review of Literature.

Non-sebaceous lymphadenoma is a sporadic benign tumor of salivary glands. Histopathologic and immunohistochemical properties, diagnostic criteria, and theories for the histologic origin of the disease have been defined and well-discussed in the literature. However, none of the cases showed malignant transformation to date. We reported a case of 54 years old female patient with a right preauricular mass. Magnetic resonance imaging demonstrated a 2 cm, well-defined contrast-enhanced mass in the right parotid gland. Fine needle aspiration cytology was undiagnostic but suspicious for malignancy. Total parotidectomy with facial nerve preservation was done. In the histopathological examination, non-sebaceous lymphadenoma regions and malignant cells with abundant cytoplasm, large vesicular nuclei, and prominent nucleoli, which occupied approximately 70% of the mass, were seen. The diagnosis was undifferentiated carcinoma arisen from non-sebaceous lymphadenoma. Adjuvant radiotherapy was given. No recurrence was detected during ten months of follow-up. This case is the first case of a malignancy developed from non-sebaceous lymphadenoma.