[A case of subfrontal schwannoma].

We encountered a rare case of subfrontal schwannoma. A 55-year-old woman had received resection of a left frontal tumor because of hyposmia, at the age of 28 years. On June 10, 1989, she was admitted with the chief complaint of progressive contraction of visual field. Neurologic examination revealed anosmia, impaired vision and concentric contraction of visual field. Fundoscopy showed optic atrophy. CT examination demonstrated a calcified mass of mixed density which was occupying her nasal cavity, ethmoid sinus and anterior skull base. The lesion was enhanced with contrast medium. MRI clearly depicted the extension of the lesion and a low signal intensity area in the left frontal lobe as a postoperative scar. Angiography showed hypovascularity. The tumor was totally removed by bifrontal craniotomy on August 22, 1989. Infiltration into the brain or compression of the optic nerve was not detected. The dura on the cranial base side was damaged and lost by infiltration of the tumor, normal olfactory bulb was not able to be identified, and the cribriform plate was broken. The anterior skull base was reconstituted by covering the dural defect with cadaveric dura and the bony defect with a pericranium. HE staining showed Antoni A&B types of schwannoma. Postoperative course was uneventful. In this case, it is most likely that a remnant of the tumor resected when she was 28 years old had developed subfrontal schwannoma a long time after the operation, although the histological type at that time was unknown. It is also possible that a primary tumor in the nasal cavity or paranasal sinus may have extended into the cranium.(ABSTRACT TRUNCATED AT 250 WORDS)