[Anterior Cranial Fossa Dural Arteriovenous Fistula with Specific Drainage Route Presenting Aphasia after Head Trauma:A Case Report].

In this case report, we describe a rare case of anterior cranial fossa dural arteriovenous fistula(ACF-dAVF)that had drained into the fronto-basal vein and refluxed to the superficial middle cerebral vein(SMCV). A 45-year-old man presented with aphasia and swelling of the left eye after head trauma. MRI detected a flow void in the left frontal basal area, and digital subtraction angiography revealed ACF-dAVF, which was fed from the ophthalmic arteries on both sides and had a shunt point within the left front basal dura. It drained into the left front basal vein and refluxed to the left SMCV via the cavernous sinus. Aphasia occurred due to the reflux of the SMCV. We treated the patient with transcatheter arterial embolization(TAE)by injecting n-butyl-2-cyanoacrylate(NBCA)into the shunt point. Immediately after TAE, the aphasia and swelling of the left eye of the patient improved. Cases of ACF-dAVF that drain not into the frontal cortical veins but into the fronto-basal vein and SMCV are relatively rare. As ACF-dAVF occasionally causes frontal symptoms such as aphasia, we should carefully investigate such patients and consider the presence of ACF-dAVF.

[A Case of Symptomatic Nonhemorrhagic and Nonthrombotic Cervicothoracic Epidural Varices].

We describe an extremely rare case of symptomatic nonhemorrhagic and nonthrombotic cervicothoracic epidural varices. A 45-year-old man presented with back pain and left leg weakness. MRI revealed an epidural mass at the Th1 level, on the dorsal aspect of the spinal canal on the right side. Although MRI scans obtained 10 days after the initial scans(obtained at the first visit to our hospital)revealed disappearance of the epidural mass at the Th1 level on non-contrast images and on images obtained 90 s after intravenous gadolinium injection, the images obtained 5 min after intravenous gadolinium injection revealed the epidural mass at the Th1 level. The patient's symptoms had resolved;therefore, we administered conservative therapy. Although the patient initially continued to show symptomatic improvement, he developed clinical relapse without any evidence of relapse on MRI. Left leg weakness and back pain worsened a year later, and repeat MRI revealed reappearance of the epidural mass at the Th1 level. Cervicothoracic laminectomy revealed nonhemorrhagic epidural varices, and we performed total en bloc resection. Histopathological examination of the resected specimen showed nonthrombotic varices. The patient's neurological symptoms improved postoperatively without relapse. Intermittent expansion of varicose veins in accordance with changes in venous pressure may cause compressive myelopathy. Clinicians should consider the possibility of spinal epidural varices in patients who present with spinal epidural lesions that tend to show intermittent improvement with subsequent worsening.

[Pseudoaneurysm of Neck External Carotid Artery Related to Chiropractic Manipulation].

A 55-year-old man presented with progressive pain and expanding swelling in his right neck. He had no history of trauma or infectious disease. The patient had undergone chiropractic manipulations once in a month and the last manipulation was done one day before the admission to our hospital. On examination by laryngeal endoscopy, a swelling was found on the posterior wall of the pharynx on the right side. The right piriform fossa was invisible. CT revealed hematoma in the posterior wall of the right oropharynx compressing the airway tract. Aneurysm-like enhanced lesion was also seen near the right common carotid artery. Ultrasound imaging revealed a fistula of approximately 1.2 mm at the posterior wall of the external carotid artery and inflow image of blood to the aneurysm of a diameter of approximately 12 mm. No dissection or stenosis of the artery was found. Jet inflow of blood into the aneurysm was confirmed by angiography. T1-weighted MR imaging revealed presence of hematoma on the posterior wall of the pharynx and the aneurysm was recognized by gadolinium-enhancement. We performed emergency surgery to remove the aneurysm while preserving the patency of the external carotid artery. The pin-hole fistula was sutured and the wall of the aneurysm was removed. Histopathological assessment of the rissue revealed pseudoaneurysm. The patient was discharged after 12 days without deficit. Progressively growing aneurysm of the external carotid artery is caused by various factors and early intervention is recommended. Although, currently, intravascular surgery is commonly indicated, direct surgery is also feasible and has advantages with regard to pathological diagnosis and complete repair of the parent artery.

[Implementation of Penumbra-assisted Half-Stent Thrombectomy for Patients with Acute M2 Occlusion:Results of Initial Experiences].

The benefits of mechanical thrombectomy(MT)for acute M2 occlusion have remained unclear because of unavoidable device-related complications due to vascular morphological characteristics. We developed a Penumbra-assisted half-stent thrombectomy for achieving secure retrieval of thrombus with minimal damage to the small-caliber vessel. In total, 6 patients were treated with MT for acute M2 occlusion using this technique between November 2016 and May 2017, including 3 men and 3 women, mean age 74.8(51-98)years. The mean baseline National Institutes of Health Stroke Scale score was 17.5(6-32), and Alberta Stroke Program Early Computed Tomography Score-Diffusion-Weighted Imaging was 7.5(6-9). After navigation of the microcatheter through the thrombus in M2 supported by a Penumbra 4MAX as a distal access catheter, the stent retriever(SR)was partially deployed to cover the entire thrombus. The 4MAX was then advanced towards the caudal end of the thrombus, and the SR was pulled back into the 4MAX with simultaneous aspiration of the 4MAX. We used the Trevo XP3 in 5 patients and Revive SE in 1 patient. The mean procedure time from groin puncture to recanalization was 60(54-66)min. Successful recanalization(Thrombolysis in Cerebral Infarction score 2b or 3)was achieved in 5(83%)patients. There were no cases of symptomatic intracranial hemorrhage. Good outcome(modified Rankin Scale score 0 to 2)at 3 months was achieved in 3(50%)patients. Penumbra-assisted half-stent thrombectomy appears to be an effective alternative strategy in MT for acute M2 occlusion.

[Multiple Spinal Intradural and Extradural Syphilis Granuloma Mimicking Lumbar Dumbbell Type Neurinoma:A Case Report].

Spinal intradural and extradural syphilis granuloma is extremely rare. Here, we report a patient with multiple spinal intradural and extradural syphilis granuloma mimicking dumbbell type neurinoma. The patient was a 68-year-old man, who presented with left femoral pain for a month. Magnetic resonance imaging(MRI)revealed a homogeneous enhanced dumbbell-shaped lesion occupying the spinal canal at the level of lumbar 3/4 and developing through the intervertebral foramen. Although initial blood tests revealed that he contracted with the syphilis, we diagnosed dumbbell type neurinoma preoperatively. He underwent partial tumor removal. The tumor adhered tightly to the cauda equina in intraoperative finding. Histopathological diagnosis of the lesion was granulomatous inflammation with the lymphocytic infiltration. Postoperatively, results of the Treponema pallidum hemagglutination(TPHA)test and the rapid plasma regain(RPR)test of cerebrospinal fluid were reactive, so we confirmed syphilis granuloma. He was treated with penicillin G for two weeks from 25 days after surgery. A follow-up MRI of the lumbar spine 51 days after surgery showed a reduction in size of the lumbar spinal tumor compared to the initial findings. Thus, syphilis granuloma should be considered in differential diagnosis of a spinal dumbbell shaped lesion. Penicillin G may be effective for the treatment of syphilis granuloma.

Long-Term Outcomes of Carotid Endarterectomy and Carotid Artery Stenting for Carotid Artery Stenosis: Real-World Status in Japan.

BACKGROUND AND PURPOSE: We investigated long-term outcomes of carotid endarterectomy (CEA) and carotid artery stenting (CAS) in our institute to evaluate the outcomes of real-world practice in Japan. METHODS: Between August 2006 and July 2013, 203 consecutive carotid revascularizations with either CEA or CAS were performed in our institute. The initial treatment was regarded as the starting point in the cases of the patients who received treatment by bilateral carotid artery stenosis or retreatment. We assessed the long-term outcomes with survival analyses. RESULTS: A total of 182 patients (CEA 111, CAS 71), including 86 symptomatic patients, were included in the current study with a mean follow-up period of 42.9 months. The periprocedural stroke/death/myocardial infarction (MI) rate was 3.6% for CEA and 5.6% for CAS groups (P = .71). Estimates of the 4-year event-free rate from the primary end point (the composite of any stroke, death, or MI within 30 days, and any ipsilateral stroke thereafter) using competing risk analysis were 3.6% for CEA and 7.1% for CAS (P = .156). Kaplan-Meier estimates of the 4-year event-free rate from the secondary end point (the composite of any stroke, death, or MI within 30 days, and any stroke or death thereafter) were 13.8% for CEA and 19.1% for CAS (P = .072). Age was the only significant predictor for the primary end point. Both age and CAS were significant predictors for the secondary end point. CONCLUSIONS: The current study on real-world practices demonstrated perioperative and long-term outcomes that were comparable to previous major studies of large numbers of patients.

MicroRNA-183 upregulates HIF-1α by targeting isocitrate dehydrogenase 2 (IDH2) in glioma cells.

MicroRNAs (miRs) are small, non-coding RNAs that regulate gene expression and contribute to cell proliferation, differentiation and metabolism. Our previous study revealed the extensive modulation of a set of miRs in malignant glioma. In that study, miR microarray analysis demonstrated the upregulation of microRNA-183 (miR-183) in glioblastomas. Therefore, we examined the expression levels of miR-183 in various types of gliomas and the association of miR-183 with isocitrate dehydrogenase 2 (IDH2), which has complementary sequences to miR-183 in its 3'-untranslated region (3'UTR). In present study, we used real-time PCR analysis to demonstrate that miR-183 is upregulated in the majority of high-grade gliomas and glioma cell lines compared with peripheral, non-tumorous brain tissue. The mRNA and protein expression levels of IDH2 are downregulated via the overexpression of miR-183 mimic RNA in glioma cells. Additionally, IDH2 mRNA expression is upregulated in glioma cells expressing anti-miR-183. We verified that miR-183 directly affects IDH2 mRNA levels in glioma cells using luciferase assays. In malignant glioma specimens, the expression levels of IDH2 were lower in tumors than in the peripheral, non-tumorous brain tissues. HIF-1α levels were upregulated in glioma cells following transfection with miR-183 mimic RNA or IDH2 siRNA. Moreover, vascular endothelial growth factor and glucose transporter 1, which are downstream molecules of HIF-1α, were upregulated in cells transfected with miR-183 mimic RNA. These results suggest that miR-183 upregulation in malignant gliomas induces HIF-1α expression by targeting IDH2 and may play a role in glioma biology.

[Allergy of calcium phosphate cement material following skull reconstruction: a case report].

The paste form of calcium phosphate cement is often used in skull reconstruction because of the biocompatibility and early handling of these cements. Although it had rarely been shown to produce a foreign body reaction, we encountered a patient who experienced an allergic reaction to calcium phosphate cements(Biopex®. A patch test was performed and a positive reaction to magnesium phosphate was obtained. Biopex® contains magnesium phosphate, so we diagnosed this case as allergic reaction. Pathological analysis revealed infiltration of plasmacytes in the bone flap around the calcium phosphate cement. The postoperative course was uneventful 3 years after surgery. Allergy to calcium phosphate cements is rare, but must be considered in differential diagnosis of its side effects.

Stent assisted coil embolization for a dissecting cerebral aneurysm of middle cerebral artery: A case report and the literature review.

Background: Dissecting aneurysms of the middle cerebral artery (MCA) are very rare. We herein report a case of an unruptured dissecting aneurysm of the MCA treated by stent-assisted coil embolization. Case Description: A 65-year-old man with no history of trauma presented with a headache. Time-of-flight imaging revealed a dissecting cerebral aneurysm in the right M1 segment of the MCA, and the aneurysm had increased in size within a short time. We treated the aneurysm by endovascular stenting with coils, and the patient developed no neurological deficits. Conclusion: Because of the potential involvement of the lenticulostriate artery (LSA) in the area of dissection, choosing the best treatment (such as direct surgery or endovascular treatment) may be challenging. Treatment efficacy depends on whether the LSA is affected and on the length of the dissection. In our case, the dissection did not involve the LSA and could therefore be treated by stent-assisted coil embolization.

An aggressive dural arteriovenous fistula manifested by unilateral subcortical calcification and cerebral edema: A case report.

Unilateral subcortical calcifications are unique radiographic findings indicating specific focal pathologies. When the lesion is accompanied by edema, cerebral neoplasm usually leads to a differential diagnosis. This report presents a case of unilateral subcortical calcification and edema that resulted in cerebral hemorrhage and a subsequent diagnosis of an aggressive dural arteriovenous fistula. A man in his 60s presented with left hemianopsia and a progressive headache for over 6 months. Initial computed tomography revealed unilateral subcortical calcification and cerebral edema in the right occipital lobe, raising the suspicion of oligodendroglioma. However, 10 days later, a cerebral hemorrhage occurred in the lesion. Magnetic resonance imaging revealed flow void clusters and dilatation of the bilateral external carotid arteries and cortical veins, indicating a dural arteriovenous fistula. Cerebral angiography confirmed the presence of a parasagittal dural arteriovenous fistula (Borden type III). The patient was successfully treated with trans-arterial embolization using Onyx. Thus, calcifications with edema are more commonly associated with cerebral neoplasms; however, in this case, they indicated the presence of a dural arteriovenous fistula with severe corticovenous reflux. The presented case highlights the importance of recognizing these imaging features in dural arteriovenous fistulas and raises awareness of the potential danger of early hemorrhage after diagnosis. Therefore, timely evaluation of cranial vessels is essential in cases of unilateral subcortical calcification and edema to facilitate the early detection and management of aggressive dural arteriovenous fistulas.

Machine Learning to Predict Three Types of Outcomes After Traumatic Brain Injury Using Data at Admission: A Multi-Center Study for Development and Validation.

The difficulty of accurately identifying patients who would benefit from promising treatments makes it challenging to prove the efficacy of novel treatments for traumatic brain injury (TBI). Although machine learning is being increasingly applied to this task, existing binary outcome prediction models are insufficient for the effective stratification of TBI patients. The aim of this study was to develop an accurate 3-class outcome prediction model to enable appropriate patient stratification. To this end, retrospective balanced data of 1200 blunt TBI patients admitted to six Japanese hospitals from January 2018 onwards (200 consecutive cases at each institution) were used for model training and validation. We incorporated 21 predictors obtained in the emergency department, including age, sex, six clinical findings, four laboratory parameters, eight computed tomography findings, and an emergency craniotomy. We developed two machine learning models (XGBoost and dense neural network) and logistic regression models to predict 3-class outcomes based on the Glasgow Outcome Scale-Extended (GOSE) at discharge. The prediction models were developed using a training dataset with n = 1000, and their prediction performances were evaluated over two validation rounds on a validation dataset (n = 80) and a test dataset (n = 120) using the bootstrap method. Of the 1200 patients in aggregate, the median patient age was 71 years, 199 (16.7%) exhibited severe TBI, and emergency craniotomy was performed on 104 patients (8.7%). The median length of stay was 13.0 days. The 3-class outcomes were good recovery/moderate disability for 709 patients (59.1%), severe disability/vegetative state in 416 patients (34.7%), and death in 75 patients (6.2%). XGBoost model performed well with 69.5% sensitivity, 82.5% accuracy, and an area under the receiver operating characteristic curve of 0.901 in the final validation. In terms of the receiver operating characteristic curve analysis, the XGBoost outperformed the neural network-based and logistic regression models slightly. In particular, XGBoost outperformed the logistic regression model significantly in predicting severe disability/vegetative state. Although each model predicted favorable outcomes accurately, they tended to miss the mortality prediction. The proposed machine learning model was demonstrated to be capable of accurate prediction of in-hospital outcomes following TBI, even with the three GOSE-based categories. As a result, it is expected to be more impactful in the development of appropriate patient stratification methods in future TBI studies than conventional binary prognostic models. Further, outcomes were predicted based on only clinical data obtained from the emergency department. However, developing a robust model with consistent performance in diverse scenarios remains challenging, and further efforts are needed to improve generalization performance.

The impact of hormonal dynamics and serum sodium fluctuations on symptomatic vasospasm after subarachnoid hemorrhage.

BACKGROUND: Symptomatic vasospasm (SVS) is a major cause of morbidity and mortality in aneurysmal subarachnoid hemorrhage (SAH), and serum sodium frequently decreases before SVS. Serum sodium changes might be regulated by sodium metabolism-related hormones. This multi-institutional prospective cohort study therefore investigated the measurement of sodium metabolism-related hormones to elucidate the pathophysiology of serum sodium changes in SAH. METHODS: SAH patients were treated with clipping or coiling from September 2017 to August 2020 at five hospitals. The laboratory data of 133 SAH patients were collected over 14 days and correlations between changes in serum sodium, sodium metabolism-related hormones (plasma adrenocorticotropic hormone (ACTH), serum cortisol, plasma arginine vasopressin (AVP)), and SVS were determined. Serum sodium concentrations were measured every day and serum sodium levels >135 mEq/L were maintained until day 14. RESULTS: Of the 133 patients, 18 developed SVS within 14 days of subarachnoid hemorrhage onset (SVS group) and 115 did not suffer from SVS (non-SVS group). Circulating AVP, ACTH, and cortisol concentrations were significantly higher on day 1 in the SVS group compared with the non-SVS group. Fluctuations in serum sodium in the SVS group were significantly higher than those in the non-SVS group. There were antiparallel fluctuations in serum sodium and potassium from days 2 to 14. CONCLUSIONS: Elevated levels of ACTH/cortisol and AVP on day 1 may be predictive markers for the occurrence of SVS. Multiple logistic regression analysis showed that serum sodium fluctuations were associated with SVS occurrence. Serum sodium fluctuations were associated with stress-related hormonal dynamics. (249 words).

Direct Carotid Cavernous Fistula Due to Rupture of a Cavernous Carotid Aneurysm Embedded Within a Prolactinoma After Cabergoline Administration.

BACKGROUND: A small number of reports have described subarachnoid hemorrhage resulting from a ruptured aneurysm embedded within a prolactinoma. To the best of our knowledge, no reports have described an embedded carotid cavernous fistula. We report a patient with carotid cavernous fistula secondary to a ruptured internal carotid artery aneurysm embedded within a prolactinoma. CASE DESCRIPTION: A 61-year-old woman was referred to our hospital with sudden headache, vomiting, and dizziness. Magnetic resonance imaging demonstrated a small acute subdural hematoma, recurrent prolactinoma, and left cavernous carotid aneurysm. Conservative therapy was initiated. Her serum prolactin level at hospitalization was 11,300 µg/L; therefore, we initiated cabergoline therapy. Twenty days after cabergoline administration, she suddenly presented with left conjunctival injection and pulsatile tinnitus. Angiography showed a left direct carotid cavernous fistula with a connection between the cavernous internal carotid artery and the cavernous sinus via the aneurysm and venous congestion. To prevent hemorrhagic stroke, we scheduled staged surgery. First, we urgently performed embolization of the cavernous sinus and fistula. One month later, to prevent aneurysm rerupture, we performed a radical operation with superficial temporal artery-middle cerebral artery double anastomosis with proximal occlusion of the left internal carotid artery at the cervical portion. The patient was discharged 2 weeks after surgery without neurological deficits. Follow-up angiography revealed complete occlusion of the aneurysm 2 months postoperatively. CONCLUSIONS: An aneurysm embedded within a prolactinoma should be closely observed when cabergoline administration is started.

Intradural facial nerve schwannoma: diagnostic and therapeutic problems.

OBJECTIVES: To define characteristics of intradural facial schwannoma (FS) and discuss management strategies. METHOD: Retrospective review of clinical charts. RESULTS: Six patients were diagnosed, based on surgical findings, as having intradural FS. None of the patients complained initially of facial weakness, but all showed severe disturbance of hearing function assessed on admission. FS was suspected in four of our six patients because of imaging findings or facial palsy caused by a small tumor. Total removal was performed in five cases followed by facial nerve reconstruction, and nearly total removal was performed in one case. Most patients recovered to Grade II or III palsy during the follow-up, and long-lasting palsy before surgery showed poor recovery. CONCLUSION: Imaging findings such as tumor extension to the middle fossa and clinical findings such as facial palsy caused by a small tumor strongly suggest a diagnosis of FS. Facial function can be restored satisfactorily for most patients after appropriate surgery.

Multiple cavernous angiomas of the cauda equina. Case report.

An 18-year-old male presented with multiple cavernous angiomas of the cauda equina manifesting as acute onset of severe low back pain radiating into the bilateral legs. Magnetic resonance imaging revealed a 20 mm by 15 mm nonenhanced, heterogeneous intensity intradural mass at the L-1 level, which had completely obliterated the spinal canal. After laminectomy at T12-L1 and dural incision, a 20 mm dark-bluish, mulberry-like tumor was seen, displacing the cauda equina circumferentially. After total removal of this tumor, four more small tumors were found adhering to different nerve roots, which were not resected. Histological examination revealed cavernous angioma. Although the postoperative course was uneventful, close observation of the residual tumors is required.

Snoring associated with Ondine's curse in a patient with brainstem glioma.

UNLABELLED: Ondine's curse is an uncommon type of sleep apnea syndrome characterized by failure of automatic respiration. We present an adult patient with brainstem glioma who presented with snoring and Ondine's curse as the only symptoms. CASE REPORT: A 52-year-old female was brought to the hospital by a fellow resident due to exceptionally loud snoring. During the hospitalization, Ondine's curse was diagnosed after monitoring using Apnomonitor 5 (Chest Co., Tokyo), a cheap, non-invasive respiratory monitoring procedure. MRI and MR spectroscopy revealed a brainstem glioma. After radiation therapy, clinical response was documented using repeat apnomonitoring. CONCLUSION: Exceptionally loud snoring in non-obese adult patients with sleep apnea may be an early feature of a brainstem space-occupying lesion. Overnight sleep respiratory evaluation and neuroimaging should be considered in such instances.

New technique for decompressive duraplasty using expanded polytetrafluoroethylene dura substitute--technical note.

A new technique for decompressive craniectomy with duraplasty was developed for cases in which brain swelling was present at dural closure. Expanded polytetrafluoroethylene (ePTFE) membrane is placed under the dura, covering the brain surface, without the use of sutures. The dura is then loosely sutured. The procedure was used in 13 patients. No leakage of cerebrospinal fluid into the epidural space or signs of infection were observed. Sutureless insertion of an ePTFE membrane at external decompression may increase the ease of duraplasty, decrease operating time, and avoid injury to the brain resulting from suturing the dura. The technique might be especially useful in emergency cases.

Acquired lumbar epidermoid cyst in an adult.

A 61-year-old female complained of low back pain, and had been treated by spinal anesthetic injection more than 70 times over 14 years. Magnetic resonance (MR) imaging, performed at the age of 47 years, revealed no abnormal lesion. However, she developed irritable hypesthetic pain in the left leg at 61 years of age. MR imaging revealed a round mass appearing isointense on the T1-weighted and slightly hyperintense on the T2-weighted images. Laminectomy revealed an epidermoid cyst, which was removed. This case clearly demonstrates that adults can acquire epidermoid tumor which very probably has an iatrogenic origin. The incidence of epidermoid tumor is low, but we should be aware of the potential adverse complications such as formation of epidermoid tumors after lumbar puncture.

[Intracranial hypovolemic syndrome with subdural hygroma developed massive hematoma: timing of treatment and histology of dural hypertrophy].

We report a case of a 43-year-old man treated by craniotomy for chronical subdural hematoma (CSH) due to spontaneous intracranial hypovolemia. The patient complained of sudden onset severe headache. Initial CT scan showed normal brain structure, and his headache improved with bed rest in a few days. However, MR images obtained for vertigo one month later demonstrated bilateral subdural hygroma extending to the supracerebellar space and diffuse dural enhancement after gadolinium infusion. We diagnosed bilateral subdural hygroma due to spontaneous intracranial hypovolemia, and observed him conservatively. Four months after onset, he complained of severe headache again and MR images revealed enlargement of bilateral CSH with mass effect, which had heterogenous intensity on the right convexity. We evacuated hematoma on the right by craniotomy and aspirated the left side hematoma using a burr hole. His headache improved 2 weeks after the operation with strict bed rest. The follow-up MR images showed disappearance of abnormal meningeal enhancement and improvement of brain sagging.

Cerebrospinal fluid interleukin-10 is a potentially useful biomarker in immunocompetent primary central nervous system lymphoma (PCNSL).

The diagnosis of primary central nervous system lymphoma (PCNSL) by radiographical examination is often difficult because of its similarity to other brain tumors. To test whether interleukin-10 (IL-10) and IL-6 can be used to distinguish PCNSL from other brain tumors that are radiographically similar, cerebrospinal fluid (CSF) levels of IL-10 and IL-6 were measured in 66 patients with intracranial tumors (PCNSLs: 26 cases; other brain tumors: 40 cases). In the patients with PCNSLs, the median CSF levels of IL-10 and IL-6 were 27 pg/mL and 5.4 pg/mL, respectively. The CSF IL-10 and IL-6 levels were significantly higher in PCNSLs than in the other brain tumors. To validate the diagnostic value of CSF IL-10 in PCNSL, we prospectively examined 24 patients with brain lesions that were suspected to be PCNSL. We observed that the CSF IL-10 levels were significantly higher in PCNSLs than in other brain tumors. At an IL-10 cutoff level of 9.5 pg/mL, the sensitivity and specificity were 71.0% and 100%, respectively. After therapy, the CSF IL-10 levels were decreased in all patients and were increased at relapse in most of these patients. Immunohistochemically, all PCNSLs, except for 1 unclassified PCNSL, expressed both IL-10 and IL-10 receptor-A. In the patients with high CSF IL-10, IL-10 expression levels in tumor were relatively higher, compared with low CSF IL-10; however, there was no significant difference between these groups. In addition, elevated CSF level of IL-10 was significantly associated with having a shorter progression-free survival (hazard ratio, 3.37; 95% confidence interval, 0.985-11.528; log-rank, P= .038). These results indicate that the CSF level of IL-10 may be a useful diagnostic and prognostic biomarker in patients with PCNSLs.