129S chwannomas are lesions that arise from the neural sheath of peripheral nerves, autonomic nerves, or cranial nerves. Nerve sheath tumors of the head and neck region mainly involve the eighth cranial nerve with only 4% occurring in the paranasal sinuses (1, 2). Occasionally, malignant schwannomas also occur in the paranasal sinuses. Sinonasal schwannomas do not have specific radiologic findings. The tumor rarely extends intracranially or intraorbitally, and imaging features can be similar to malign neoplasms (3).
Case reportA 71-year-old woman presented with a 1.5-month history of medial deviation and diplopia of the left eye. She also had nasal obstruction but did not have epistaxis. An anterior rhinoscopy and an endoscopic examination showed a solid mass at the level of the middle turbinate and the roof of the nasal cavity. A thick, mucopurulent secretion was noted. Paranasal sinus computed tomography (CT) scan showed a 5 × 3.5 × 3 cm expansile soft tissue mass in the left ethmoidal sinus extending through the left frontal sinus superiorly and the right ethmoidal sinus medially. Erosion and destruction of the left ethmoidal sinus and dehiscence of the bony cribriform plate were seen. Bone fragments were seen within the mass. The left middle turbinate could not be separated from the mass. The nasal septum was deviated to the right. There were erosions in the lamina papyracea to the left of the mass, which caused an indentation of the left medial rectus muscle (Fig. 1).Cranial magnetic resonance imaging (MRI) examination was performed to better assess intracranial extension. The lesion was hypointense on T1-weighted images and contained hypointense and hyperintense areas on T2-weighted images. There was heterogeneous enhancement after contrast injection. The left frontal bone and sinus were invaded by the tumor, but there was no dural enhancement or brain edema (Fig. 2). The differential diagnosis of the tumor included benign and malignant tumors of the sinonasal cavity such as squamous cell carcinoma, olfactory neuroblastoma, lymphoma, and schwannoma. Biopsy of the nasal mucosa revealed a schwannoma.The endoscopy-assisted tumor resection was performed under general anesthesia. During the surgery, the mass could not be separated from the middle turbinate, from which it was thought to have originated (Fig. 3), and was excised with it. There was a 2.5 × 1 cm defect in the dura at the base of the skull. The dural defect was repaired with the auricular conchal cartilage and the septal bone grafts (Fig. 4). Pathologically, the tumor was a whitish-brown soft tissue mass, rubbery in consistency. Light microscopy showed spindle-shaped undulating cells in the loose myxoid stroma. The lesion contained cellular and hypocellular regions. There was ulceration and necrosis in the superficial part of the lesion. ABSTRACT Paranasal schwannomas are uncommon lesions, representing less than 4% of all head and neck schwannomas. They give rise to nonspecific symptoms such as nasal obstruction, epistaxis, and anosmia. Imaging fe...
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