A fibrotic nodule arising from the cerebellopontine angle

The authors present an extremely rare case of a fibrotic nodule arising from the cerebellopontine (CP) angle. A 57-year-old male had suffered from hearing disturbance and tinnitus for several years. Computed tomography revealed a high-density mass in the left CP angle with little enhancement after intravenous administration of contrast media. Magnetic resonance imaging (MRI) showed a very hypointense mass on T2-weighted imaging. T1-weighted MRI with gadolinium revealed very faint, delayed enhancement of the tumor. The patient underwent surgical resection of the tumor. Histopathologically the lesion comprised entirely fibrotic tissue consisting of thick collagenous fibers and sclerosing blood vessels with a few intervening viable cells with, partly, the immunophenotype of arachnoid cells. Intracranial fibrotic nodules are extremely rare. This tumor, however, had some radiological features similar to those of other, more common, tumors for example meningiomas or solitary fibrous tumors; it was, therefore, difficult to distinguish it from the others. It is believed that intracranial fibrotic nodules usually have benign, non-neoplastic characteristics, although their natural history is not yet fully understood. It is, therefore, necessary to be able to perform a differential diagnosis that will distinguish this rare condition from other intracranial fibrous neoplasms that occasionally have malignant features.