Arachnoid Cyst Research Articles

Computerized Tomography Texture Analysis in the Differential Diagnosis of Intracranial Epidermoid and Arachnoid Cysts.

This study evaluated the differences between arachnoid and epidermoid cysts in computerized tomography (CT) texture analysis (TA). The study included 12 patients with intracranial epidermoid cysts and 26 patients with intracranial arachnoid cysts who were diagnosed with diffusion-weighted magnetic resonance imaging (DW-MRI) and who had undergone an unenhanced CT examination before treatment. The LIFEx application software was used to obtain texture features. Eighty-two texture features from 38 lesions were automatically calculated for each lesion. The Shapiro-Wilk test was used to test the normality of the scores, and the Mann-Whitney U Test was used to test the difference between the groups. Receiver operating characteristic (ROC) curves and multivariate logistic regression modeling examined the parameters' diagnostic performances. The median age of the patients was 53 years (range: 19-88 years). Eighty-two texture parameters were evaluated in the first order: gray-level co-occurrence matrix (GLCM), gray-level run length matrix (GLRLM), neighbor gray-tone difference matrix (NGTDM), and gray-level size zone matrix (GLSZM) groups. There was a statistically significant difference between the arachnoid cyst and the epidermoid cyst in the variables of compacity, compactness 1, compactness 2, sphericity, asphericity, sum average, coarseness, and low gray-level zone (p<0.05). According to the multiple logistic regression model, it was determined that the sum average in the GLCM group (B=-0.11; p=0.015), coarseness (B= 869.5; p=0.044) in the NGTDM group, and morphological sphericity (B=24.18; p=0.047) were the radiomics variables that increased the probability of epidermoid diagnosis. According to the classification table of the model, the sensitivity rate was found to be 83%, and the specificity rate was found to be 96%. Therefore, the probability of accurate model classification was 92%. CT TA is a method that can be applied with high diagnostic accuracy in the differential diagnosis of intracranial epidermoid and arachnoid cysts, especially in patients who cannot undergo an MRI examination.

The Role of Aquaporin 1 in Water Retention Mechanism of Arachnoid Cysts: Insights from 3 Case Reports.

BACKGROUND Although arachnoid cysts are common lesions, the pathogenesis of their continuous growth remains unclear. We aimed to identify the role of aquaporins in arachnoid cyst specimens. CASE REPORT We selected 3 cases from our own facility and examined arachnoid cyst wall specimens, which were sampled intraoperatively. Patients presented with variable symptoms, a 52-year-old man with a "heavy sensation" in the head and dysesthesia on the left hand, a 68-year-old man with unsteady gait, and finally a 26-year-old woman with a history of intermittent headaches for 10 years. Intraoperative specimens were obtained and examined. Evaluation techniques were light microscopy, immunohistochemical staining for aquaporin, and electron microscopy. Light microscopy showed that cells were arranged in epithelium-like structures forming several thick lamellae, with visible connective tissue among them. Under electron microscopic examination, cells with many or few cell organelles and with spindle-like nuclei were arranged in lamellar or flattened structures. Many vacuolizations were seen in between. Interdigitation of cells and many desmosomes were observed. All 3 cases were positive for aquaporin 1. CONCLUSIONS Our study showed that water transportation through aquaporin 1 has a potential role in the formation and expansion of arachnoid cysts.

Endoscopy-assisted purely total outer wall excision for pediatric Sylvian arachnoid cysts

BackgroundTo present a novel endoscopy-assisted surgical strategy of Sylvian arachnoid cysts (ACs).Case presentationEndoscopy-assisted surgery was performed on 9 children (May 2019–December 2021). All patients were evaluated with CT and/or MRI and had regular follow-up examinations. The procedure consisted of performing a small temporal craniotomy (2 cm) behind the hairline. After dural opening, the surgery was performed with the assistance of a rigid 30-degree transcranial endoscope, self-irrigating bipolar forceps, and other standard endoscopic instruments. Steps included total excision of the AC outer wall and dissection of arachnoid adhesion around the cystic edge to communicate the residual cyst cavity with subdural space. Compared with the microscopical procedure, a 30-degree transcranial endoscope provides a wider view, especially for the lateral part exposure of the outer wall.The average age of the patients was 27.7 months (range 13–44 months). The Sylvian AC was in the right hemisphere in three patients and six in the left, respectively. 1 patient suffered transient postoperative epilepsy. There was no mortality or additional postoperative neurological deficit in this series. All of the patients achieved significant clinical improvement after surgery. Radiological examination after the operation showed a significant reduction in all cases (100%, 9/9) and disappearance in one case (11.1%, 1/9). Postoperative subdural fluid collection occurred in six cases and completely resolved spontaneously in 9 months.ConclusionThe study demonstrated the minimally invasive, safety, and effectivity of the endoscopy-assisted purely total outer wall excision.

A case study and review of the literature regardingextradural spinalarachnoid cyst

Arachnoid cysts are spaces containing cerebrospinal fluid partitioned into an arachnoid-formed sheath and are a rare cause of symptomatic spinal cord compression. This case study examined a patient with spastic paraparesis who underwent surgery to remove the cystic lesion and push back the marrow. Post-op control spinal MRI showed total excision of the cyst, and the patient has progressed well and has fully recovered from his deficit. Nabors divides extradural arachnoid cysts into three types: type 1, type 2, and type 3. Type 1 is essentially thoracic, extending over several vertebrae with a peak of greater frequency around the eighth dorsal vertebra. Symptoms are generally slowly progressive, but rapid revelation or decompensation are possible. Treatment options include marsupialization, wide resection, and total excision. For symptomatic cases, total excision is the reference treatment. For painful cases, complete excision, tied off the intradural communication pedicle, and reshaping the dura is the primary surgical goal.

An anisotropically diffusible fuzzy clustering based image segmentation methodology for intracranial cyst detection

An Intracranial cyst is an abnormal growth of mass in the brain that affects functioning of the nervous system and so an early detection of the lesion enables to avoid adverse effects. The processing unit in the Magnetic Resonance Imaging (MRI) system performs reading the images followed by primary image enhancement to suppress distortions thereby enhancing the feature quality in terms of its intensity, augmenting the resolution by image segmentation, post-processing by thresholding based on grayscale values and performing several morphological operations. With the existing methodologies, extracting the Region Of Interest (ROI) with the overlapping intensity values lead to inaccurate results. A novel method in which the input image that is anisotropically diffused and blurred is converted into a sharp image. Further, fuzzy partitioning of pixels deployed on Global Thresholding –Clustering Methodology (GT-CM) based segmentation takes 4 clusters into account hence forth seperating the exterior portion of the skull, the border region of the skull, the ventricles which may include the lesion and the noise. Statistical results based on several metrics such as sensitivity, specificity, F measure, Jaccord Index, Dice Coefficient and precision show that the proposed method is far more effective. An accuracy of 99.26% is obtained in exactly locating and extracting the lesion along with its attributes.

Incidence and Surgical Outcomes of Intracranial Arachnoid Cysts: A Systematic Review Comparing Endoscopic Fenestration, Open Craniotomy and Cystoperitoneal Shunt Approaches

ABSTRACT Background: Arachnoid cysts (ACs) are non-neoplastic collections of cerebrospinal fluid, often posing challenges in diagnosis and management due to their rarity and varied clinical presentations. This systematic review aims to investigate the frequency of ACs, analyse optimal intervention approaches and evaluate neurological complications postoperatively. Materials and Methods: A systematic search of Science Direct, PubMed and Cochrane databases was conducted using controlled vocabulary terms and keywords. Inclusion criteria encompassed studies focusing on adults with symptomatic ACs requiring surgical intervention. Data extraction involved factors influencing subdural haemorrhage, surgical techniques, drainage types and imaging approaches. Adherence to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines ensured methodological rigor and transparency. Results: The review identified multiple surgical approaches, including microsurgical fenestration, endoscopic fenestration and cystoperitoneal shunt, tailored to different cyst locations. Studies showed cystoperitoneal bypass as effective for supratentorial cysts, endoscopic fenestration for midline cysts and cystoperitoneal shunt for infratentorial cysts. Notably, endoscopic fenestration exhibited a 90% success rate, while cystoventricular drainage emerged as an alternative option. However, limitations in comparative studies and variations in follow-up durations hindered comprehensive analyses. Conclusion: Cystocysternostomy, preferably minimally invasive, showed promising outcomes in managing ACs. Wide endoscopic fenestration was recommended without causing damage to adjacent structures. Surgical adaptation for uncontrolled bleeding during procedures was suggested. Intracranial shunts were preferred due to lower infection risks. Postoperative care involving anticonvulsants and conservative antibiotic therapy exhibited low complication rates. Despite limitations in available evidence, this review highlights potential effective interventions for managing ACs, emphasising the need for further comprehensive studies.

Intradural Spinal Arachnoid Cysts in Children: A Collective Experience of 2 Centers

Pediatric intradural spinal arachnoid cysts are rare and can cause spinal cord or nerve root compression. Spinal arachnoid cysts can cause pain, motor/sensory neurological impairments, gait disturbances, spasticity, and bladder problems depending on their location. This study discusses the clinical aspects, management, surgical nuances, and postoperative clinical outcomes of symptomatic congenital intradural spinal arachnoid cysts, which are rarely seen in the pediatric population. Our study involves a retrospective evaluation of 8 pediatric patients who underwent surgery for spinal intradural arachnoid cysts at the Department of Neurosurgery, Kocaeli University School of Medicine, and the Department of Neurosurgery, Selros University School of Medicine. The demographic data of all patients, preoperative/postoperative clinical findings, surgical procedures, surgical complications, and radiological imaging were evaluated. The average age of the patients was 8.7 uated. surgicrange:1-17).The female to male ratio was 4:4. The most common complaint was weakness in the lower extremities (87.5%). Urinary problems (50%) and sensory disturbances (50%) were less frequently observed. All patients had dorsal localization of the cysts. Cyst excision was performed in 7 out of 8 patients, and cyst fenestration was performed in 1 patient. Postoperatively, 7 patients showed complete symptom resolution, while one patient had partial improvement. The success of surgical treatment depends on cyst location, neural tissue compression, and duration of symptoms. Complete removal or fenestration is determined by cyst location and accessibility. Intracystic shunts may be used in certain cases. Timely diagnosis and surgical intervention are crucial for improving neurological function in these rare cases.

How to locate the fistula orifice of spinal extradural arachnoid cyst: Surgical experience and clinical outcome

BackgroundIn clinical practice, spinal extradural arachnoid cysts (SEAC) are relatively rare. The key to the treatment of SEAC is recognize and close the dural defects (fistula orifice), but there is currently no convenient method to locate and identify the fistula. We propose a method for predicting the location of lumbar/thoracolumbar SEAC fistula based on surgical experience, subsequently closing the fistula through posterior unilateral interlaminar fenestration. Evaluating its surgical efficacy and investigated its effect on patient prognosis.MethodsA stepped approach based on clinical experience is proposed. A retrospective analysis was performed on 6 patients diagnosed with thoracolumbar SEAC disease and treated with posterior unilateral interlaminar fenestration through the position by pre-estimated fistula orifice in our hospital’s Department of Neurosurgery between January 2017 and January 2022.ResultsAll patients who received this treatment experienced significantly lower postoperative VAS pain scores and ODI index compared to their corresponding preoperative values (P < 0.01). During the ongoing follow-up after surgery, no unstable vertebral column, adverse effects, or complications were reported.ConclusionsThe use of posterior unilateral interlaminar fenestration for the treatment of large SEAC in the adult lumbar/thoracolumbar segment can reduce spinal cord manipulation and enhance spine stability. The disease can be treated by sealing the fistula orifice through a small fenestra, the position of which is assessed before surgery. This surgical method reduces trauma and improves the prognosis of patients with large SEAC.

A rare association between intracranial neuroenteric cyst and Klippel-Feil syndrome: a case report

A rare association between intracranial neuroenteric cyst and Klippel-Feil syndrome: a case report

How to understand an enlarged Meckel's cave? An anatomical study.

Dilatation of the trigeminal cavum, or Meckel's cave (MC), is usually considered a radiological sign of idiopathic intracranial hypertension. However, the normal size of the trigeminal cavum is poorly characterized. In this study, we describe the anatomy of this meningeal structure. We dissected 18 MCs and measured the length and width of the arachnoid web and its extension along the trigeminal nerve. Arachnoid cysts were clearly attached to the ophthalmic (V1) and maxillary (V2) branches until they entered the cavernous sinus and foramen rotundum, respectively, without extension to the skull base. Arachnoid cysts were close to the mandibular branch toward the foramen ovale, with a median anteromedial extension of 2.5 [2.0-3.0] mm, lateral extension of 4.5 [3.0-6.0] mm, and posterior extension of 4.0 [3.2-6.0] mm. The trigeminal cavum arachnoid had a total width of 20.0 [17.5-25.0] mm and length of 24.5 [22.5-29.0] mm. Our anatomical study revealed variable arachnoid extension, which may explain the variability in size of the trigeminal cavum in images and calls into question the value of this structure as a sign of idiopathic intracranial hypertension. The arachnoid web extends beyond the limits described previously, reaching almost double the radiological size of the cavum, particularly at the level of V3 afference of the trigeminal nerve. It is possible that strong adhesion of the arachnoid to the nerve elements prevents the formation of a true subarachnoid space that can be visualized by magnetic resonance imaging.

Thoracic Anterior Spinal Cord Herniation: Treatment and Prognosis Outcome of Seven Patients

This study aimed to investigate the diagnosis and treatment of thoracic anterior spinal cord herniation, a rare condition. Clinical data of 7 patients diagnosed with thoracic anterior spinal cord herniation were analyzed. All patients were diagnosed with a complete preoperative examination and scheduled for surgical treatment. In addition, regular follow-up was performed after the surgery, and the operation's efficacy was evaluated according to clinical symptoms, imaging findings, and improvement in neurologic function. All patients underwent spinal cord release with an anterior dural patch. Notably, no severe postoperative surgical complications were observed. All patients were followed up for 12-75months, with an average duration of approximately 46.5months. Post-operative pain symptoms were controlled, neurological dysfunction and related symptoms improved to varying degrees, and anterior spinal cord herniation did not recur. The modified Japanese Orthopedic Association score at the last follow-up was significantly higher than the preoperative score. Clinicians should avoid misdiagnosing patients with thoracic anterior spinal cord herniation with intervertebral disc herniation, arachnoid cysts, and other related diseases, and patients should undergo surgical treatment as early as possible. In addition, surgical treatment can protect the neurologic function of patients and effectively prevent the aggravation of clinical symptoms.

Prenatal Diagnosis of Costello Syndrome Using Noninvasive Prenatal Single Gene Testing With Maternal Blood

Introduction Costello syndrome (CS) is a rare disorder that affects multiple organ systems, which is usually diagnosed postnatally, except for 2 cases diagnosed prenatally from chromosome analysis by amniocentesis. We present the first case of prenatally diagnosed CS via maternal blood testing. Case Description A 38-year-old woman was referred for genetic screening at 28 weeks of gestational age (GA) due to polyhydramnios and shortened limbs seen on prenatal ultrasound. Cell-free DNA, noninvasive prenatal single gene screening was positive for G12S HRAS mutation, which is indicative of CS. The infant was delivered via elective repeat cesarean section at 36 weeks and 6 days GA, was admitted to the neonatal intensive care unit for respiratory distress. Physical examination was significant for macrocephaly, wide depressed nasal bridge, short neck, rhizomelic limb shortening, micropenis, and bilateral equinovarus deformity of the feet. Echocardiography on the first day showed severe pulmonary hypertension. Brain MRI showed a possible cavernous mass lesion and small arachnoid cyst over the left cerebellar hemisphere. Postnatal gene-targeted testing confirmed CS diagnosis with pathogenic variants. The infant was managed for respiratory distress, hypoglycemia, jaundice, and feet deformities. He was subsequently transferred to another hospital at 45 weeks of age for gastrostomy tube placement due to persistent difficulty with oral feeding. Discussion CS affects multiple organ systems. Clinical presentations includes short stature; macrocephaly; coarse facial features, loose and soft skin; hypotonia and joint laxity; cardiac involvement with congenital heart defect, feeding difficulty, and developmental delay. The phenotypic spectrum is wide and can range from mild features to early lethal complications mostly as a result of severe progressive Hypertrophic Cardiomyopathy (HCM) and respiratory compromise. CS is an autosomal dominant genetic disorder caused by mutations in the HRAS gene, but almost all cases have new mutations with no family history. Disease course depends on cardiac and predisposition to benign and malignant tumor complications. Treatment requires a multidisciplinary team directed toward the specific clinical findings. Conclusion To our knowledge, this is the first reported case of prenatally diagnosed CS via maternal blood testing. Molecular diagnosis in the prenatal period allows neonatal care providers to prepare for potential complications in the postnatal period.

Treatment of symptomatic sacral arachnoid cysts in the pediatric population.

Symptomatic sacral arachnoid cysts are extremely rare in pediatric patients, resulting in a lack of consensus regarding optimal treatment measures. The current study evaluated the clinical symptoms and surgical indications, techniques, and outcomes of pediatric patients who underwent treatment for sacral arachnoid cysts with the aim of developing recommendations for follow-up and treatment. This retrospective study included pediatric patients who underwent surgical treatment for sacral arachnoid cysts between January 2000 and December 2020 at the Department of Pediatric Neurosurgery, Acıbadem University Faculty of Medicine. Thirteen patients were included in the study, 9 of whom were girls and 4 were boys. Five patients presented with urinary incontinence, 2 of whom also exhibited constipation. Other chief complaints included recurrent urinary tract infections (UTIs) and low-back pain (n = 4 patients each). Urological evaluation was performed in all patients, followed by urodynamic examination in those with urinary symptoms. Spinal MRI showed extra- and intradural sacral cysts in 12 patients and 1 patient, respectively. The latter patient exhibited recurrence during follow-up and underwent reintervention. Samples from the excised cyst walls were sent for pathological examination. Five patients with urinary incontinence, 2 with constipation, 4 with recurrent UTIs, and 3 with low-back pain exhibited resolution of symptoms after treatment. However, 1 patient with low-back pain did not show any improvement in symptoms. No postoperative complications were observed in the current study. The patients were followed-up regularly after surgery, and the mean follow-up duration was 4 years. Sacral arachnoid cysts in pediatric patients may be associated with urinary system dysfunction and low-back pain. Surgery is the treatment of choice for symptomatic patients and those with enlarged cysts with radiological evidence of compression, and the morbidity and mortality rates associated with surgery are low.

Redo Aortic Surgery in a Patient with a Large Arachnoid Cyst and Myelodysplasia.

A 70-year-old man was referred for redo root and ascending aortic surgery. Preoperative investigations depicted a large arachnoid cyst occupying the left frontotemporal region and myelodysplasia with persistent thrombocytopenia. We describe successful operative management of this patient in the context of such rare intracranial pathology.

Surgical feasibility for arachnoid cyst resolution: an integrative literature review

Objective: To investigate the scientific collection on the cases of Arachnoid Cysts (ACs) portrayed in the literature in which surgical intervention was necessary, which approaches were used and their success. Methodology: This is an integrative literature review carried out in the Virtual Health Library (VHL), in the Latin American and Caribbean Literature in Health Sciences (LILACS) databases and the Online System for Searching and Analyzing Medical Literature (MEDLINE), with the descriptors: “Arachnoid Cyst” AND “Surgery” and filters: full text, languages: Portuguese and English, in the time frame of the last 10 years (2013-2022). Results and discussion: Of the 32 articles found, 10 were excluded due to thematic leakage, unavailability in full or due to duplication, totaling a final corpus of 10 studies. Final Considerations: There was convergence on the need for surgical intervention only in symptomatic cases and its high resolution. However, there is a divergence regarding the best surgical method, taking into account the specificities of each case.

Hyperplasia of Arachnoid Trabecular Cells: A Hitherto Undescribed Lesion Observed in the Setting of Neurofibromatosis Type 1.

Central nervous system manifestations, a variety of benign and malignant tumors as well as non-neoplastic abnormalities, are found in over 70% of neurofibromatosis type 1 (NF1) patients. Herein, we report hitherto undescribed space-occupying lesions in the setting of NF1. We aimed to clarify their characteristics, especially whether they represent neoplastic or non-neoplastic (hyperplastic) lesions. All 3 cases were preoperatively assessed as non-neoplastic; 2 and 1 cases were suspected to be arachnoid cysts and dilation of subarachnoid space, respectively. However, all lesions were revealed to be whitish jelly-like masses by operation, and the histology composed of spindle cells resembling arachnoid trabecular cells with moderate cellularity and cellular uniformity gave an impression that these lesions may be neoplastic. In contrast, electron microscopic analysis showed that the characteristics of these cells were compatible with those of normal arachnoid trabecular cells. Furthermore, whole-exome sequencing and array comparative genomic hybridization did not show any obvious alterations suggestive of their neoplastic nature. DNA methylation analysis demonstrated that these lesions were epigenetically distinct not only from meningiomas but also from normal healthy meninges. In conclusion, considering the clinicopathologic aspects of the present lesions and the results of the molecular analysis that failed to suggest their neoplastic nature, they may represent previously unrecognized rare hyperplasia of arachnoid trabecular cells, which may be associated with NF1.

A rare case of bleeding into the Sylvian arachnoid cyst: A case report

Arachnoid cysts are primarily developmental in origin and constitute rare, benign lesions. Sylvian arachnoid cysts may infrequently present with subdural and/or intracystic hemorrhage. Hemorrhage is typically of venous origin and occurs due to stretching and tearing of bridging veins, depending on minor traumas. The annual risk of bleeding associated with Sylvian arachnoid cysts, with no additional complaints other than headache and an asymptomatic course, has been reported to be 0.04%. Symptoms can range from headache to coma, depending on the mass effect after hemorrhage. If there is no clinical evidence linking the arachnoid cyst, it is sufficient to perform surgery only for the hematoma without resecting it. In this case report, we present a rare instance of hemorrhage due to a Sylvian arachnoid cyst that developed after trauma and was observed in a patient who came to our clinic with a headache. In our patient, the cyst-dependent left parietal subdural hemorrhage was evacuated through a burr-hole craniotomy, and a closed-system drainage with a Hemovac drain was applied for 48 hours. During post-operative follow-up, complete resorption of subdural and intracystic hemorrhages was observed. A case-based surgical approach is necessary for bleeding due to arachnoid cysts in the Sylvian region.

Sports Participation and Sports-Related Neurologic Injuries in Pediatric Patients With Arachnoid Cysts.

Currently, there is no consensus recommendation regarding the safety of sports participation for pediatric patients with arachnoid cysts (ACs). To prospectively survey patients with ACs to define the risk of sports-associated neurologic injury in untreated and treated patients. A prospectively administered survey was given to all patients diagnosed with an AC who presented to a single pediatric neurosurgery clinic between December 2010 and December 2021. Data were recorded on demographic information, imaging characteristics, treatment, sports participation, and presence of sports-related neurologic injury. The type and date of surgery for the AC were noted if surgery was performed. Of the 303 patients with completed surveys, 189 patients participated in sports, and 94 patients had prospective data available. There was no significant difference in cyst location or Galassi score between patients who did and did not participate in contact vs noncontact sports and those who did and did not experience a concussion. A cumulative total of 2700.5 seasons of sports were played (2499.7 in untreated and 200.8 in treated patients). There were 44 sports-related concussions among 34 patients: 43 in untreated patients and 1 in a treated patient. For all participants, the concussion rate was 16.3 per 1000 seasons of all sports and 14.8 per 1000 seasons of contact sports. The concussion rate after AC treatment was 4.9 per 1000 seasons of all sports. Three patients experienced sports-related AC rupture or hemorrhage, none of which required surgery or resulted in lasting neurologic symptoms or deficits. The rates of sports-related concussion and cyst rupture in patients with AC in both treated and untreated populations were low. We advocate for a generally permissive posture toward sports participation in this population.

Characterizing Various Posterior Fossa Tumors in Children and Adults With Diffusion-Weighted Imaging and Spectroscopy.

Background Theposterior fossa is situated between thetentorium cerebelli above and the foramen magnum below. Vital structures like the cerebellum, the pons, and the medulla are situated within it; hence, tumors within the posterior fossa are considered one of the most critical brain lesions. Children are more likely to develop posterior fossa tumors than adults. Diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) sequences along with the conventional MRI helpin providing additional information in the characterization of the various posterior fossa tumors. We hereby present a series of 30 patients with clinically suspected posterior fossa masses who underwent preoperative MRI. Objectives This study aims to differentiate the neoplastic from non-neoplastic posterior fossa mass by evaluating the diffusion restriction pattern on DWI, quantifying the apparent diffusion coefficient (ADC) map in various posterior fossa tumors, and comparing the different metabolites of various posterior fossa tumors on MRS. Results Out of the 30 patients with posterior fossa lesions, 18 were males and 12 were females. Eight of them were in the pediatric age group, while twenty-two of them were adults. Metastasis was the most common posterior fossa lesionin our study sample and was found in six patients (20%), followed by vestibular schwannomas (17%) and arachnoid cysts (13%), meningiomas, medulloblastoma, and pilocytic astrocytoma (10% each) and epidermoid, ependymoma, and hemangioblastoma (7% each). The mean ADC value of benign tumors was higher than that of malignant tumors, and this difference was found to be significant (p = 0.012). The cut-off ADC value 1.21x 10-3mm2/s had a sensitivity of 81.82% and specificity of 80.47%. MRS metabolites played an additional role in differentiating benign from malignant tumors. Conclusion A combination of conventional MRI, DWI,ADC values, and MRS metabolites showed good diagnostic accuracy to differentiate between the various posterior fossa neoplastic tumors both in adults and children.

Malignant Transformation of an Intracranial Epidermoid Cyst 25 Years After Initial Surgery: A Case Report and Systematic Review

We report a unique case of a suspected recurrent intracranial epidermoid cyst (EDC) that was found on pathology to have undergone malignant transformation to squamous cell carcinoma (SCC) approximately 25years after initial resection. Additionally, we performed a systematic review including 94 studies reporting intracranial EDC to SCC transformation. Ninety-four studies were included in our systematic review. PubMed, Scopus, Cochrane Central, and EMBASE were searched in April 2020 for studies regarding histologically confirmed SCC arising within an EDC. Kaplan-Meier estimations were used to estimate time to event including survival, and log rank tests were used to test for significance. All analyses were conducted using STATA 14.1 (StataCorp, College Station, Texas, USA); tests were two-sided, and statistical significance was defined using the alpha threshold of 0.05. The overall median time to transformation was 60months (95% confidence interval {CI}, 12-96). Transformation time was significantly shorter in the no surgery group (10months, 95% CI undefined) versus the other 2 groups (60months, 95% CI, 12-72 in surgery only and 70months, 95% CI, 9-180 in surgery+adjuvant therapy group, both P < 0.01). Overall survival was significantly longer in the surgery+adjuvant therapy group (13months, 95% CI, 9-24) versus the other 2 groups (3months, 95% CI, 1-7 in surgery only and 6months, 95% CI, 1-12 in the no surgery group, both P<0.01). We report a rare case of delayed malignant transformation of an intracranial EDC to SCC, occurring nearly 25years after initial resection. Transformation time in the no-surgery group was statistically significantly shorter as compared to the surgery only and surgery+adjuvant therapy groups. Overall survival was statistically significantly higher in the surgery+adjuvant therapy group as compared to the surgery only and no surgery groups.