[Pleomorphic adenoma in unusual anatomic sites: case reports and review of literature]

Pleomorphic adenoma is the most common neoplasm of the major salivary glands, in particular of the parotid gland. Only occasionally can it be found in the cervicofacial area outside the major and minor salivary glands of the oral cavity. The present article describes three cases of pleomorphic adenoma, respectively of the external auditory canal, the nose, and the larynx. The three tumors showed no clinical or radiological signs of malignancy and were surgically excised with a suitable margin of healthy tissue. Histologically, the typical features of pleomorphic adenoma were observed in the larynx case alone. The pleomorphic adenoma of the external auditory canal evidenced an extensive apocrine glandular component; the neoplasm of the nose was itself characterized by ample proliferation of fused cells. Immunohistochemical findings revealed focal or widespread positivity to cytokeratin, S100 protein and muscle-specific actin in both the epithelial and mesenchymal components of the neoplasm. Cases of pleomorphic adenoma in sites other than the major salivary glands show clinical and radiological signs of benignity. Their histopathological identification is, however, not always straightforward; immunohistochemistry can contribute significantly to the formulation of a definitive diagnosis and to the realization of an appropriate follow-up.