[Benign extracranial cervical-facial schwannomas: anatomo-clinical and diagnostic considerations on our case reports and review of literature]

Abstract

Schwannoma is a rare neoplasm in the E.N.T. areas although it is characteristic of this discipline. Indeed, examination of the most recent data in the literature shows that approximately 45% of all neoplasms of the peripheral nerve linings occur in the head and neck district, the most common neurogenic tumors are schwannomas and these constitute 35% of all head and neck tumors. In reviewing the literature attention was focused on schwannomas originating in unusual sites, neglecting the most common sites originating in the eighth and seventh pair of cranial nerves. It was seen that the site of origin and clinical manifestation of these lesions varies widely and the four cases presented here are no exception. These are four schwannomas which came under observation between 1994 and 1997. The sites of origin were, respectively: the floor of the mouth, the submandibular region (corresponding to the Warthon duct), the anterior wall of the external auditory canal and the hypopharynx (corresponding to the pyriform sinus). All of these cases proved quite rare in the literature. All the cases underwent accurate anatomopathological examination and the paper discusses the particular histological and immunohistochemical features encountered. Reference is also made to the problems of differential diagnosis vs. other types of soft tissue tumors. Emphasis is placed on the demonstrated difficulty in recognizing schwannomas from the macroscopic and surgical points of view. The absence of mitoses, necroses, invasiveness and specific features--i.e. hyperchromia and pleomorphism of the nuclei or the presence of large atypical cells--are all parameters confirming that the lesions observed in the present study were benign. No anatompathological features were observed that could justify any particular expression of the schwannoma in the specific sites involved. Nevertheless, the authors present these case because a review of the literature indicated that they are extremely rare and because differential diagnosis of these unusual manifestations is so complex.