Recurrent plexiform schwannoma involving the carotid canal.

Plexiform schwannoma (PS) is a rare variety of benign nerve sheath tumor characterized by a multinodular plexiform growth pattern. PS is usually confined to the head and neck or skin. The pre-operative diagnosis of PS is difficult, and this has lead to a common misdiagnosis as a schwannoma. In addition, studies have indicated that an incomplete resection of PS often results in tumor recurrence. Here we describe a rare case of PS presented in the parapharyngeal space. Our case involved a 36-year-old man with swelling of the pharynx, who presented with a soft cervical mass. MRI revealed a multinodular mass in the left parapharyngeal space, and further pathological diagnosis by the referral hospital indicated schwannoma. A cervical approach was taken and the tumor was removed with preservation of the nerve sheath by intracapsular resection. The tumor recurred within one year after the first surgery in the same lesion of the left parapharyngeal space. The second surgical approach was a combination of a facial dismasking flap and trans-pterygopalatine fossa. The mass was resected completely, and the diagnosis of PS was confirmed by histopathology. While schwannoma commonly occurs in the head and neck, parapharyngeal space PS is rare, and pre-operative pathological diagnosis of PS is difficult. MRI studies of PS revealed distinctive features that we found useful in pre-operative diagnosis. Intracapsular resection of PS with nerve preservation has a very high recurrence rate of the tumor. Therefore, if MRI findings suggest PS we recommend removing the tumor completely without nerve preservation will offer the most curative outcome.