In this report, we introduce an undetermined fibrous tumor with calcification occurring in the cerebellopontine angle (CPA). XIIIa and smooth muscle actin. The diagnosis was not compatible with meningioma, schwannoma, metastatic brain tumors, and other fibrous tumors. Although the tumor was resected in total, long term follow-up monitoring is necessary due to the possibility of recurrence. strong class=”kwd-title” Keywords: Calcification, Cerebellopontine angle, Immunohistochemistry, Tumor INTRODUCTION Intracranial tumors with calcification, which are present at cerebellopontine angle (CPA), consist of various benign and malignant tumors including Linifanib inhibition meningioma, schwannoma, malignant glioma, metastasis and solitary fibrous tumors (SFT)1,2,4,10). Preoperative diagnosis is done by computed tomography, magnetic resonance (MR) images and thallium-201 SPECT which show dural involvement, bony erosion, proliferation potential and infiltration pattern to the normal parenchyma8,23). Differential diagnosis is a critical issue because the tumor can be treated not only by medical excision but also with radiosurgery, regular radiotherapy based on medical and radiological features16). Nevertheless, it really is sometimes difficult to look for the analysis and really should end up being confirmed from the histopathologic exam as a result. Right here, we present a uncommon case of fibrous tumor with calcification that was located at remaining CPA. Even though the tumor was resected altogether, long-term follow-up monitoring is essential for the feasible recurrence. CASE Record A 51-year-old female was admitted having a history background of dizziness for a number of weeks. She didn’t display any hearing impairment, cosmetic palsy or cerebellar symptoms. Computed tomography (CT) exposed a 2 2 2 cm size mass in the remaining CPA. Linifanib inhibition Thallium-201 SPECT didn’t display thallium uptake upsurge in tumor in comparison to contralateral cerebellum (data not really shown). There is no electrophysiologic proof facial audiogram and neuropathy led to normal range. In MR images, the tumor was hypointense signal on T2-weighted image and isointense on T1-weighted image with minimal contrast enhancement (Fig. 1). In addition, there was no contrast enhancement of the dura including left tentorium cerebelli. Furthermore, it seemed not to be related to the lower cranial nerves. At surgery, we identified that the tumor was very firm, bright yellow and well encapsulated round mass. It was also not adherent to the adjacent dura mater. Linifanib inhibition The tumor was completely resected via a left suboccipital approach. After removal, there was small arachnoid adhesion at root exit region of 7th and 8th cranial nerve complex but no connection with these cranial nerves (Fig. 2). Histopathologically, the tumor was predominantly composed of fibrous component, scant spindle cells and dystrophic calcification. Immunohistochemical staining demonstrated positive for vimentin and negative for epithelial membrane antigen (EMA), S-100 protein, CD34, factor XIIIa and smooth muscle actin (Fig. 3). Open in a separate window Fig. 1 In computed tomography, calcifying mass is seen at left cerebellopontine angle region (A) and T2-weighted magnetic resonance (MR) image shows hypointense lesion on left cerebellopontine angle (CPA) (B). The axial (C) and coronal (D) gadolinium enhancement MR images show isointense lesion with minimal enhancement on left CPA and there is no dural enhancement or internal auditory involvement of the tumor. Open in a separate window Fig. 2 The tumor is bright yellow and well circumscribed and it is not adhered to tentorium (T). A : Supeior petrosal vein (arrow) and 9th nerve (curved arrow) are observed. B : After tumor removal, arachnoid adhesion (arrow) adjacent to the exit of the 7th and 8th nerve complex (arrow Bmp8a head) is observed. Open in a separate window Fig. 3 Histopathological examination shows dystrophic calcification (arrow) and spindle cells (H&E,400) (A). Immunohistochemistry for vimentin is positive (B). The postoperative course was uneventful and 6 months follow-up MR images did not show remnant tumor or recurrence (Fig. 4). Open in a separate window Fig. 4 T2-weighted (A) and gadolium enhanced T1-weighted (B and C) MR images checked 6 months after the surgery show no remnant or recurrence. DISCUSSION Considering CT and MR images that the tumor was located in extraaxial CPA region, main differential diagnosis included meningioma, schwannoma and rarely metastatic tumors at first. Meningioma is usually originated from arachnoid meningothelial cells and the dural membrane involving tumor shows strong contrast enhancement in MR pictures, although isolated meningioma can seldom be noticed24). Histopathologically, meningiomas.