Fibrous Connective Tissue Lesion Mimicking a Vestibular Schwannoma: Case Report Liana Beni-Adani, M.D., Felix Umansky, M.D., Dov Sofer, M.D., Ph.D., Moshe Gomori, M.D., Ph.D. Departments of Neurosurgery (LB-A, FU), Pathology (DS), and Neuroradiology (MG), Hadassah University Hospital, Jerusalem, Israel OBJECTIVE AND IMPORTANCE: Cerebellopontine angle fibromas are rare pathological entities that can mimic the presentation of vestibular schwannomas (VSs). Diagnosis of these benign lesions, however, is im- portant, because treatment options may be different. The clinical, radio- logical, and intraoperative features of these unusual lesions of the cer- ebellopontine angle are discussed, with review of the relevant literature. CLINICAL PRESENTATION: A 41-year-old man presented with recurrent episodes of diminished hearing on the left side, accompanied by facial ticks and pain on the same side. Magnetic resonance imaging and com- puted tomographic scans revealed a 1.5-cm, primarily intracanalicular lesion, suggesting a left VS. INTERVENTION: The lesion was partially removed through a retrosigmoid suboccipital craniotomy. Its intraoperative appearance and hard fibrotic consistency differed from the classic features of VSs. The pathological findings indicated nontumoral fibrous connective tissue. The lesion ex- hibited no features of inflammation or fat and was also negative for S-100 staining. Follow-up magnetic resonance imaging scans demonstrated a small residual lesion, which exhibited shrinkage in subsequent magnetic resonance imaging studies. The painful ticks disappeared and facial nerve weakness improved postoperatively. CONCLUSION: Although cerebellopontine angle fibromas may present similar radiological features, their clinical presentation may be somewhat different from that of typical VSs. If a fibroma is suspected, radiosurgery should be avoided; limited surgery may be considered as an option for patients expe- riencing symptoms. Because fibromas may be intraoperatively noted to be fibrotic and vascular, radical removal may not be easy or justified. After the final diagnosis has been reached, conservative treatment of the residual lesion may be the best option. (Neurosurgery 47:1234–1238, 2000) Key words: Acoustic neuroma, Cerebellopontine angle, Facial pain, Fibroma, Magnetic reso- nance imaging, Vestibular schwannoma V estibular schwannomas (VSs), which are also termed acoustic neu- romas, are by far the most common tu- mors in the cerebellopontine angle (CPA) (3). It is accepted that other tu- moral or inflammatory lesions may ap- pear in 8 to 10% of cases (2). As de- scribed by the Otologic Medical Group (2) and others, these less common le- sions include meningiomas, cholesteato- mas, other cranial nerve schwannomas, arachnoid cysts, tumors of vascular ori- gin, metastatic tumors, astrocytomas, medulloblastomas, dermoids, chondro- sarcomas, chordomas, lipomas, choles- terol granulomas, choroid plexus papil- lomas, and teratomas (2, 5, 9). To our knowledge, no similar case of a CPA fibroma has previously been de- scribed, with presentation of magnetic resonance imaging (MRI) findings, com- puted tomographic (CT) findings, and pathological features. We therefore present a case of an intracanalicular fi- broma protruding into the CPA and mimicking some clinical and radiologi- cal characteristics of a VS. CASE REPORT A 41-year-old male patient presented with several episodes of left-sided facial pain and contractions and fluctuating hearing abnormalities, which began 6 months before admission. The facial pain appeared as attacks lasting a few minutes, usually accompanied by tinni- tus and diminished hearing on the same side. The attacks were sporadic, appear- ing every few weeks (more frequently in hot weather). During one of these at- tacks, the patient was admitted to an- other hospital. At that time, he also com- plained of significantly diminished hearing. He was treated with corticoste- roids, and some improvement was no- ticed. However, the event was repeated within weeks, and MRI was eventually performed. No nausea, headache, or vertigo was reported. The past medical history of the patient included recurrent bilateral otitis media for 5 years before admission. In the examination, the patient exhib- ited diminished but still functional hear- ing on the left side, with a speech dis- crimination score of 55% and a pure- tone audiogram threshold of 40 dB, and normal hearing on the right side. There were no facial or other cranial nerve deficits, and the rest of the neurological and physical examination results were normal. CT and MRI scans of the head indi- cated an intracanalicular lesion on the 1234 Beni-Adani et al. Neurosurgery, Vol. 47, No. 5, November 2000