Collision tumors of the paranasal region: presentation of two cases.

Collision tumors in the paranasal region are extremely rare with limited literature data. To the best of our knowledge, this is the first report of associations of squamous cell carcinoma-esthesioneuroblastoma and lymphoma-hemangiopericytoma in the paranasal region. Preoperatively, radiological and clinical findings should be evaluated carefully for the diagnosis and two or more biopsy specimens should be taken from different morphological parts of the lesions. Adjuvant therapy should be planned according to two different histologies and special importance should be given to the tumor which indicates the prognosis of the patient. A multidisciplinary approach is required for the management of synchronous malignancies.