Fine-needle aspiration (FNA) and pleural fluid cytology diagnosis of benign metastasizing pleomorphic adenoma of the parotid gland in the lung: A case report and review of literature

Lesions that contain abundant benign myoepithelial cells, including pleomorphic adenomas of salivary gland origin, may present a diagnostic challenge in fine-needle aspiration (FNA) specimens. Benign metastasizing pleomorphic adenoma is a rare neoplasm, in which the benign appearing pleomorphic adenoma, without any histological evidence of malignancy, metastasizes to distant sites including lung. In the absence of clinical history of a pre-existing myoepithelial neoplasm, the presence of myoepithelial cells in the lung or any other organs besides salivary glands may create diagnostic difficulty. Here we present the cytologic findings of such a metastatic tumor found in the lung FNA and pleural fluid specimens from a 64-year-old woman, with a history of local recurrent salivary gland pleomorphic adenomas, who presented with multiple bilateral pulmonary nodules and pleural effusion. The diagnosis of benign metastasizing pleomorphic adenoma was made based on clinical information and cytomorphology, and confirmed by immunocytochemistry.