[Subfrontal schwannoma: report of a case].

Subfrontal schwannoma is extremely uncommon. By reviewing the literature, we are able to find 8 previously described cases. This report describes a very rare case of solitary schwannoma grown in the anterior cranial fossa. A patient, 23 years old male, had experienced generalized convulsion on April 4, 1981. On the Tc99m scintigram, accumulation of isotope was observed in the left anterior cranial fossa. The carotid angiography revealed that the tumor stain was supplied from ophthalmic artery and orbitofrontal artery. CT showed an area with relatively low density in the left frontal base. This area was well enhanced following contrast injection. Coronal CT revealed that the tumor was contiguous with the left olfactory groove. The tumor was removed on May 12, 1981. The left fronto-temporal post-operative epidural hematoma was observed after the operation but his post-operative course was relatively satisfactory. Histological section of tumor showed interwinning bundles of cells with pallisading on hematoxylin and eosin. Pathological study showed such pallisading of the tumor cells, which confirmed that the tumor was schwannoma. While the precise origin of this unusually situated schwannoma remains uncertain, it appears most likely that the origin was from either ectopic, or perivascular nerve plexus schwann cells or dural branch of trigeminal nerve. Because the branch of the trigeminal nerves or anterior ethmoidal nerves is distributed to the meninges, the trigeminal nerve is covered with schwann cells after penetrating the pia mater in the anterior cranial fossa.(ABSTRACT TRUNCATED AT 250 WORDS)