Intracranial cystic lesions: a review

Reliable detection of genetic alterations in cyst fluid DNA for the diagnosis of brain tumors

PURPOSE

Liquid biopsy of cyst fluid in brain tumors has not been extensively studied to date. The present study was performed to see whether diagnostic genetic alterations found in brain tumor tissue DNA could also be detected in cell-free DNA (cfDNA) of cyst fluid in cystic brain tumors.

METHODS

Cyst fluid was obtained from 22 patients undergoing surgery for a cystic brain tumor with confirmed genetic alterations in tumor DNA. Pathological diagnoses based on WHO 2021 classification and diagnostic alterations in the tumor DNA, such as IDH1 R132H and TERT promoter mutation for oligodendrogliomas, were detected by Sanger sequencing. The same alterations were analyzed by both droplet digital PCR (ddPCR) and Sanger sequencing in cyst fluid cfDNA. Additionally, multiplex ligation-dependent probe amplification (MLPA) assays were performed to assess 1p/19q status, presence of CDKN2A loss, PTEN loss and EGFR amplification, to assess whether differentiating between astrocytomas and oligodendrogliomas and grading is possible from cyst fluid cfDNA.

RESULTS

Twenty-five genetic alterations were found in 22 tumor samples. All (100%) alterations were detected in cyst fluid cfDNA by ddPCR. Twenty of the 25 (80%) alterations were also detected by Sanger sequencing of cyst fluid cfDNA. Variant allele frequency (VAF) in cyst fluid cfDNA was comparable to that of tumor DNA (R = 0.62, Pearson's correlation). MLPA was feasible in 11 out of 17 (65%) diffuse gliomas, with close correlation of results between tumor DNA and cyst fluid cfDNA.

CONCLUSION

Cell-free DNA obtained from cyst fluid in cystic brain tumors is a reliable alternative to tumor DNA when diagnosing brain tumors.

Correlation of Brain Metastasis Genomic Alterations with Preoperative Imaging Features

BACKGROUND

The aim of this study was to examine associations between genomic alterations in brain metastases and common preoperative imaging findings including overt intratumoral hemorrhage, cystic features, and edema.

METHODS

A single-center, retrospective study was performed including patients who underwent surgical resection of brain metastasis with available preoperative magnetic resonance imaging (MRI). Next-generation sequencing of more than 500 coding genes was performed on the resected brain metastases. Preoperative MRI was reviewed to identify the presence of intratumoral hemorrhage, cystic features, and edema in the resected brain metastasis. Genomic data were then correlated with the imaging features using univariate and multivariate nominal logistic regression analyses.

RESULTS

We included 144 brain metastases from 141 patients in the study cohort. Half (72) of the metastases had an intratumoral hemorrhage, 26 (18%) had cystic features, and 130 (90%) had edema. Mutations in TP53 were associated with a reduced risk of intratumoral hemorrhage (odds ratio [OR] 0.2, 95% confidence interval [CI] 0.07-0.5, P < 0.001). Mutations in RB1 and CCND1 were associated with elevated risk of the metastasis having cystic features (OR 10.3, 95% CI 2.0-52.6, P = 0.005, OR 18.4, 95% CI 2.2-155.3, P = 0.008, respectively). PIK3CA mutations were associated with a reduced risk of peritumoral edema (OR 0.2, 95% CI 0.04-0.8, P = 0.03).

CONCLUSIONS

Several genomic alterations in brain metastases are associated with MRI features including hemorrhage, cystic features, and edema. These results provide insight into tumor biology and patients at risk of developing these imaging features.

Imaging of congenital and developmental cystic lesions of the brain: a narrative review

INTRODUCTION

Congenital and developmental intracranial cysts represent a large heterogenous group with varied presentations and etiologies. They can range from normal variants to pathologic lesions often associated with known congenital syndromes or acquired insults. While some are incidentally found, others are symptomatic or may become symptomatic over time. The preferred type of neuroimaging for timely diagnosis helps determine appropriate management and treatment, if indicated.

AREAS COVERED

In this narrative review article, authors present a comprehensive description of developmental cystic lesions. Imaging descriptions are provided for each type of cystic lesion as well as several representative images.

EXPERT OPINION

As advanced neuroimaging techniques become more ubiquitous in clinical use, more light may be shed on the natural history of certain intracranial cystic lesions throughout the lifespan. This includes prenatal imaging for early identification and prognostication to surveillance imaging into advanced age to ascertain associations of certain cystic lesions with age-related cognitive dysfunction.

Spontaneous resorption of a convexity arachnoid cyst associated with intracystic hemorrhage and subdural hematoma: A case report

Background

Intracranial arachnoid cysts (ACs) are developmental anomalies usually filled with cerebrospinal fluid (CSF), rarely resolving throughout life. Here, we present a case of an AC with intracystic hemorrhage and subdural hematoma (SDH) that developed after a minor head injury before gradually disappearing. Neuroimaging demonstrated specific changes from hematoma formation to AC disappearance over time. The mechanisms of this condition are discussed based on imaging data.

Case Description

An 18-year-old man was admitted to our hospital with a head injury caused by a traffic accident. On arrival, he was conscious with a mild headache. Computed tomography (CT) revealed no intracranial hemorrhages or skull fractures but an AC was seen in the left convexity. One month later, follow-up CT scans showed an intracystic hemorrhage. Subsequently, an SDH appeared then both the intracystic hemorrhage and SDH gradually shrank, with the AC disappearing spontaneously. The AC was considered to have disappeared, along with the spontaneous SDH resorption.

Conclusion

We present a rare case where neuroimaging demonstrated spontaneous resorption of an AC combined with intracystic hemorrhage and SDH over time, which may provide new insights into the nature of adult ACs.

An epileptogenic intracranial cystic lesion lined with fallopian tube-type epithelium: illustrative case

BACKGROUND

Intracranial cystic lesions are often a trigger for epileptic seizures. However, there has never been a report of a cystic lesion lined with fallopian tube-type epithelium.

OBSERVATIONS

A 48-year-old female presented with a cystic lesion in the right occipital lobe, which gradually grew over 8 years. Right occipital lobe epilepsy was diagnosed based on visual aura, convulsive seizures, and electroencephalogram findings and the cyst was surgically removed. Further examination revealed the cyst was lined with ciliated cells, which had morphological and immunohistochemical features similar to those of fallopian tube epithelium.

LESSONS

The characteristics of the cyst did not conform to any known types of benign cystic lesion. To the authors' knowledge, no such cyst has been reported before. The authors discuss the origins and pathogenesis of this unfamiliar cystic lesion.

Endoscopic endonasal resection of an epidermoid cyst in the cavernous sinus: A case report and literature review

Background

Epidermoid cysts of cavernous sinus (CS) are rare congenital neoplasms of the central nervous system. In previous literature reports, the treatment for CS epidermoid cysts was mainly microsurgical resection, and the surgical methods included simple microsurgery and endoscope-assisted microsurgery. The present case report demonstrates the first case of complete resection of a CS epidermoid cyst by a simple endoscopic endonasal transcavernous (EET) approach.

Case presentation

A 54-year-old woman presented with chronic persistent headaches and occasional syncope. Brain MRI demonstrated a space-occupying lesion of the left CS, and digital substruction angiography (DSA) showed a small aneurysm at the beginning of the left ophthalmic artery. Thrombotic therapy of carotid-ophthalmic aneurysms was performed first, and the patient underwent resection of the CS lesion secondary. Considering the location of the lesion and the neuroendoscopy technology and experience of the doctor, we made bold innovations and used an EET approach to achieve complete resection of the lesion. The postoperative pathological results were consistent with the characteristics of epidermoid cyst. During the 1-year follow up, the patient showed no apparent signs of recurrence on head MRI.

Conclusion

Epidermoid cyst of cavernous sinus is a rare benign occupying lesion in cavernous sinus. Reviewing the previous literature, the main treatment is microneurosurgery, and neuroendoscopy is only used as an auxiliary equipment. We present the first case of complete endoscopic resection of CS epidermoid cyst by EET approach according to CARE guidelines, aiming to share the new surgical plan for CS epidermoid cyst and provide more surgical options for this disease for neurosurgery colleagues.

Intracranial Epidermoid Cyst Mimics Musculoskeletal Shoulder Disease: Findings from a Case Report in Physiotherapy Clinical Practice

Shoulder pain is often attributable to a musculoskeletal disorder, but in some instances, it may be linked to pathologies outside the physiotherapist's area of expertise. Specifically, some intracranial problems can cause pain and disability to the shoulder complex. This case report aims to describe the clinical presentation, history taking, physical examination, and clinical decision-making procedures in a patient with an intracranial epidermoid cyst mimicking a musculoskeletal disorder of the shoulder girdle. A 42-year-old man complained of pain and disability in his left shoulder. Sudden, sharp pain was reported during overhead movements, associated with intermittent tingling of the left upper trapezius and left scapular area. Moreover, the patient reported reduced hearing in his left ear and left facial dysesthesia. The physical examination led the physiotherapist to hypothesize a pathology outside the physiotherapist's scope of practice and to refer the patient to another health professional to further investigate the patient through imaging. It is essential for the physiotherapist to recognize when the patient's clinical condition requires a referral to another healthcare professional. Therefore, the physiotherapist must be able to, in a timely manner, identify signs and symptoms suggesting the presence of medical pathology beyond his expertise, through appropriate medical history collection and physical evaluation.

Frame-based stereotactic implantation of cystoventricular shunts for treating acquired intracerebral cysts

OBJECTIVE

The treatment of symptomatic, progressive or recurrent acquired intracerebral cysts is challenging, especially when they are localized in eloquent structures. In addition to resection, endoscopic fenestration, or stereotactic puncture, the implantation of a cystoventricular shunt by stereotactic guidance (SCVS) has been reported as a minimally invasive procedure; however, only scarce data are available regarding its feasibility and efficacy. Here, the authors evaluated the feasibility and efficacy of frame-based SCVS in patients with acquired intracranial cysts.

METHODS

In this single-center retrospective analysis, the authors included all patients with acquired intracerebral cysts treated by SCVS following a standardized prospective protocol between 2012 and 2020. They analyzed clinical symptoms, complications, and radiological outcome with regard to cyst volume reduction by 3D volumetry.

RESULTS

Thirty-four patients (17 females and 17 males; median age 44 years, range 5-77 years) were identified. The median initial cyst volume was 11.5 cm3 (range 1.6-71.6 cm3), and the mean follow-up was 20 months (range 1-82 months). At the last follow-up, 27 of 34 patients (79%) showed a cyst volume reduction of more than 50%. Initial symptoms improved or resolved in 74% (n = 25) and remained stable in 24% (n = 8). No permanent clinical deterioration after treatment was observed. The total complication rate was 5.9%, comprising transient neurological deterioration (n = 1) and ventriculitis (n = 1). There were no deaths. The overall recurrence rate was 11.8%.

CONCLUSIONS

In this study, SCVS proved to be a safe, minimally invasive, and effective treatment with reliable long-term volume reduction, resulting in clinical improvement and a minor complication rate.

Choroid plexus cyst causing acute hydrocephalus and transtentorial herniation: report of a rare case and its successful neuroendoscopic treatment

Choroid plexus cysts (CPC) are a frequent incidental neuroimaging finding and completely asymptomatic in the vast majority of cases. We hereby describe a rare case of acute hydrocephalus secondary to a CPC, atypical in size, location and presentation, which required urgent neuroendoscopic management. There are very few reported cases of CPC causing obstructive hydrocephalus. The authors present the case of a previously healthy 2-year-old boy with severe symptoms of acute intracranial hypertension, triventricular hydrocephalus, and left ventricle exclusion after placement of a right external ventricular drain. Magnetic resonance imaging (MRI) showed a very subtle gadolinium enhancement in the anterior region of the third ventricle and foramen of Monro (FM). An emergency neuroendoscopic exploration was performed, where a big cyst was found in the choroid plexus near the FM. The foramen was completely unblocked by thoroughly fenestrating and coagulating the cyst, and a preventive endoscopic septum pellucidotomy was done in the same procedure. The patient completely resolved his symptoms, without neurological morbidity or requirement of a cerebrospinal fluid shunt placement. It is important to consider this infrequent presentation in cases of acute or intermittent obstructive hydrocephalus without apparent cause, bearing in mind its difficult detection in neuroimaging studies and the possibility of effective neuroendoscopic treatment.

Advanced magnetic resonance imaging and spectroscopy in a case of neurocysticercosis from North America

Neurocysticercosis (NCC) is a parasitic infection caused by Cysticercus cellulosae, the metacestode of pork tapeworm (Taenia solium). NCC is one of the most common public health problems worldwide. We present a patient harboring a bilobed ring-enhancing lesion with a presumed diagnosis of brain metastasis, who returned to the USA after traveling to an endemic region. The diagnosis of NCC was established based on a characteristic resonance of succinate on proton magnetic resonance spectroscopy. Also, higher mean diffusivity and lower fractional anisotropy along with relative cerebral blood volume were observed from the lesion compared to contralateral normal brain regions. Multiparametric analysis may improve the differential diagnosis of ring-enhancing intracranial lesions such as NCC.

Supratentorial Intraparenchymal Neurenteric Cyst Treated by Neuroendoscopic Fenestration: A Case Report and Review of Literature

Neurenteric cysts (NCs) are rare benign congenital neoplasms in the central nervous system that originate from endodermal elements. NCs are more commonly located in the spine than in the brain. Although almost all intracranial NCs are found in the posterior fossa, some have reported supratentorial NCs. The complete excision of the cyst wall is suggested as a curative treatment; however, endoscopic treatment is less discussed. We present a supratentorial intraparenchymal NC in the frontal lobe treated by neuroendoscopic fenestration and review the literature regarding supratentorial NCs. A 43-year-old woman presenting with right hemiparesis and gait disturbance who was found to have a huge cystic lesion with calcification in her left frontal lobe underwent endoscopic fenestration to the ipsilateral lateral ventricle and biopsy. The histopathological diagnosis was consistent with NC. Postoperatively, her right hemiparesis and gait disturbance disappeared. Postoperative MRI showed shrinkage of the cyst. She was discharged without neurological deficits and no recurrence was seen 1 year after surgery. To the best of our knowledge, there have been no reports of a supratentorial intraparenchymal NC treated by neuroendoscopic fenestration. Minimally invasive treatments, such as neuroendoscopic cyst fenestration, can be considered depending on the location of the cyst.

What provokes a disappearing arachnoid cyst? - Case study and literature review

OBJECTIVE

Intracranial Arachnoid cysts (AC) are stable cerebral spinal fluid (CSF)-filled sacs that can rarely undergo progressive shrinkage or disappearance throughout life. In this manuscript, we present a case of post-traumatic complete resolution of an AC, review the possible triggers of this phenomenon, and discuss the pathophysiological mechanisms behind them.

METHODS

After presenting our case, we performed a literature review using the PubMed Database of all the reported cases of AC reduction or resolution (last updated in February 2021). Spontaneous cases were excluded. An analysis of the remaining cases (1985-2021) according to their inciting event, demographical, and clinical characteristics was then presented.

RESULTS

58 patients were identified, 33 of which spontaneously resolved. The remaining 25 were included in the survey in addition to the case we presented. The mean age was 20.2 years, average time to resolution was 25.3 months, with only two third of the cases showing complete disappearance of the AC. A central nervous system infection was the inciting cause of resolution in one infant (4%), a history of head trauma in 16 (62%) patients and an intracranial procedure in 9 (35%) patients.

DISCUSSION

AC disappearance is a rare phenomenon that can occur spontaneously or after an inciting event. The cyst wall rupture and CSF flow perturbation theories seem to be the most applicable pathophysiological mechanisms in triggered AC resolution.

Ruptured Suprasellar Dermoid Cyst Treated With Lumbar Drain to Prevent Postoperative Hydrocephalus: Case Report and Focused Review of Literature

Background: Ruptured intracranial dermoid cysts are extremely rare. Standard treatment consists of endonasal decompression or craniotomy with evacuation and copious irrigation of subarachnoid spaces to remove any disseminated cystic contents. Disseminated fat particles in the subarachnoid space may be the cause of further sequalae, including the subsequent development of chemical meningitis and hydrocephalus. Here, we present a case of ruptured suprasellar dermoid cyst treated with craniotomy for emergent optic nerve decompression, followed by postoperative hydrocephalus successfully treated with lumbar drain.

Case description: We describe a 30-year-old man with a history of migraines who presented with acute onset of headache, photophobia, nausea, vomiting, and vision loss in the left eye. Head CT and brain MRI demonstrated a ruptured suprasellar dermoid cyst with associated mass effect on the optic nerves and frontal lobes as well as fat attenuation material within the subarachnoid spaces. The patient underwent left frontotemporal craniotomy for cyst resection and developed non-obstructive hydrocephalus on postoperative day 1, refractory to external ventricular drainage. Placement of a lumbar drain cleared the subarachnoid space of debris derived from the ruptured dermoid cyst, and the hydrocephalus resolved. The patient did not require permanent CSF diversion.

Conclusions: Intracranial dermoid cysts are uncommon, and rupture is a rare event. Standard surgical treatment with craniotomy for evacuation may leave disseminated dermoid contents and fat particles throughout the subarachnoid spaces. We highlight a case of ruptured suprasellar dermoid cyst with postoperative communicating hydrocephalus treated with lumbar drain when external ventricular drain (EVD) was ineffective. Review of the current literature reveals inconsistent findings on the effects of remaining fat particles. In cases with clinical evidence of increased intracranial pressure due to non-obstructive hydrocephalus attributable to chemical meningitis, temporary lumbar drainage is an option to be considered before committing the patient to permanent shunting.

Colloid cyst of the third ventricle

A colloid cyst is a malformation composed of an amorphous, gelatinous material surrounded by epithelial and connective tissue. It is typically located in the third ventricle, leading to signs of increased intracranial pressure and hydrocephalus. In this case report, we discuss a classic presentation of a patient presenting with a colloid cyst of the third ventricle. This includes the patient's symptoms before arriving at the emergency department and presentation upon arrival and during their hospital stay. We also discuss the diagnostic approach to colloid cysts, providing radiographic imaging to support the diagnosis. Finally, we discuss the approach to treatment of a colloid cyst, including temporizing measures to relieve symptoms and definitive measures for removal of the colloid cyst. The overall approach from diagnosis to management to definitive treatment of a colloid cyst requires an interdisciplinary approach but prompt recognition of the signs and symptoms in the ED can decrease both morbidity and mortality associated with this potentially fatal diagnosis.

Dissemination Patterns and Short-Term Management of Multifocal Rosette-Forming Glioneuronal Tumors

BACKGROUND

Multifocal rosette-forming glioneuronal tumors (RGNTs) are challenging to manage. Gross total resection is often impossible, and data on adjunctive therapies are limited. We reviewed cases of multifocal RGNTs in the literature with special focus on dissemination patterns and management.

METHODS

A literature review was conducted using PubMed and the key words "(multifocal OR multicentric OR satellite OR dissemination) AND glioneuronal."

RESULTS

There were 21 cases of multifocal RGNTs identified. Follow-up was available in 18 cases at a median of 17 months. Progression-free survival and overall survival at 1 year were 84% and 94%, respectively. Of all cases, 43% had cerebrospinal fluid (CSF) dissemination, 48% had intraparenchymal spread, and 10% had both. The presence of CSF dissemination led to palliative care and/or death in 20% of cases (n = 2). None of the cases with intraparenchymal spread progressed. Radiotherapy was used in 50% of cases with CSF dissemination, chemotherapy was used in 20%, and CSF shunting was used in 36%. No tumors with intraparenchymal spread required adjunctive therapy or shunting.

CONCLUSIONS

RGNTs with CSF dissemination are more likely to behave aggressively, and early adjunctive therapies should be discussed with patients. Tumors with intraparenchymal spread grow slowly, and maximal safe resection followed by observation is likely sufficient in the short term. Long-term behavior of multifocal RGNTs is still unclear.

Appearance of cerebellar cyst following microvascular decompression to treat hemifacial spasm: a report of two cases and literature review

Microvascular decompression (MVD) is an effective and safe approach for treating hemifacial spasm (HFS). Postoperative complications may include facial nerve palsy, hearing loss, intracerebral haematoma, and brainstem infarction. The occurrence of intracranial cyst following MVD is extremely rare, with few cases documented in the literature. Herein, the cases of two patients with HFS who developed ipsilateral cerebellar cyst following MVD are reported. The first patient was a 50-year-old male presenting with a 6-year history of HFS on the right side of his face. MVD was performed, and 12 days postoperatively he developed dizziness and nausea. Magnetic resonance imaging (MRI) showed a cyst in the ipsilateral cerebellum. Antibiotic treatment provided no benefit, and the cyst was drained. The second patient was a 44-year-old female presenting with a 4-year history of HFS on the right side of her face. MVD was performed, and 18 days following surgery, she developed dizziness and nausea. MRI showed an ipsilateral cerebellar cyst. Conservative treatment was applied and the cyst shrunk. At the 2-month follow-up appointment, symptoms were completely resolved in both patients. Cerebellar cyst is a rare complication following MVD. Timely diagnosis and appropriate treatment should be emphasized, and surgical treatment may be unnecessary.

Symptomatic lateral ventricular cystic lesion in a young cat

Case summary

A 1.5-year-old male neutered Persian cat was referred for acute deterioration of chronic left head tilt and ataxia. A lateral intraventricular cystic lesion, closely associated with the left choroid plexus, was identified on MRI. The intralesional signal intensity and cytological analysis of the fluid revealed a liquid similar to cerebrospinal fluid. After trepanation, an endoscopic-assisted fenestration and aspiration of the cyst were performed to temporally relieve the high intracranial pressure while waiting for surgical cystoperitoneal shunt placement. Three weeks after surgery, clinical relapse and recurrence of the lesion were noted on the pre-cystoperitoneal shunting MRI. During anaesthesia, the cat arrested. Cardiac resuscitation was successfully performed and cystoperitoneal shunting was postponed. Global brain ischaemia was then suspected, based on major forebrain clinical signs and MRI abnormalities. During a 6-month recovery period, a further three fine-needle CT-guided aspirations of the lesion were required, owing to clinical recurrence and increased cyst size. Cystoperitoneal shunting was eventually performed, allowing persistent reduction of the lesion and long-term improvement of the cat’s neurological status.

Relevance and novel information

This is the first report of a symptomatic lateral intraventricular cystic lesion in a cat. A left lateral intraventricular choroid plexus cyst was suspected based on the MRI features. Our case suggests that endoscopic fenestration and CT-guided aspiration are not adequate treatments for long-term management. Cystoperitoneal shunting may be a safe procedure, allowing significant and stable reduction of the cystic lesion, associated with improvement in the cat’s neurological status by preventing high intracranial pressure.

The (Un)Resolved Case: Blurry vision, left foot drop and brain cysts

This clinical vignette describes the interdisciplinary diagnostic approach to a patient with cystic brain lesions. The scope of this case is to develop the clinical reasoning skills of trainees in clinical neuroscience, taking into account alternative diagnoses and unusual clinical presentations.

A Mistaken Diagnosis of Secondary Glioblastoma as Parasitosis

Background: Glioblastoma is a malignant brain tumor with poor prognosis requiring early diagnosis. Secondary glioblastoma refers to cases that progressed from low-grade glioma. Evidence shows that timely resection correlates with increased survival.

Case presentation: We describe a case of a patient with secondary glioblastoma who was mistakenly diagnosed with Angiostrongylus cantonensis infection until 7 years after disease onset. The patient presented with non-specific clinical manifestations at disease onset. A conventional magnetic resonance imaging (MRI) in the primary survey provided insufficient information, and thus failed to identify the malignancy. During follow-up, unfortunately, clinicians were misled by the patient's raw food diet, a positive serum parasite antibody and a result of low glucose metabolism on Fluorodeoxyglucose-positron emission tomography-computed tomography (FDG-PET-CT). The patient was diagnosed with parasitosis. However, his condition kept getting worse under antiparasitic treatment. Preoperative magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) failed to reverse the mistaken impression. Final diagnosis was confirmed until intraoperative and postoperative pathological findings indicated glioblastoma.

Conclusion: We ascribe the incorrect diagnosis to insufficient understanding on imaging manifestations of brain neoplasm as well as clinical features of parasitosis. Thus, we review the MRI, FDG-PET-CT, MRS, and DTI data of this case according to the timeline, refer to relevant studies, and point out the pitfalls. With a long course of slowly progressing, this was a rare case of secondary glioblastoma with the absence of isocitrate dehydrogenase 1 (IDH1) gene mutation.

Genomic profile of a primary squamous cell carcinoma arising from malignant transformation of a pineal epidermoid cyst

Malignant transformation of intracranial epidermoid cysts is a rare occurrence. We present the second case of such an event occurring in the pineal region and the first case sent for detailed genomic profiling. MRI demonstrated two lesions: a cyst in a quadrigeminal cistern with restricted diffusion on DWI-weighted images and an adjacent, peripherally enhancing tumor with cerebellar infiltration. Both the lesions were completely resected with a small residual of the epidermoid cyst. The final pathology of both lesions was consistent with epidermoid cyst and squamous cell carcinoma (SCC), respectively. The tumor specimen was sent for comprehensive genomic profiling which revealed stable microsatellite status and loss of CDKN2A/B, MTAP (exons 2-8), and PTEN (exons 6-9). Although reports of primary SCC originating from the epidermoid cyst have been previously described, this is the first description of the genomic profile of such a tumor.

[Intracranial cystic lesions]

CLINICAL PROBLEM

Intracerebral cysts are common findings in imaging of the neurocranium and are not always clinically significant. The pathological spectrum of intracerebral cysts is, however, very broad and in addition to incidental findings includes developmental disorders, malformation tumors, primary and secondary neoplasms and infectious etiologies, such as cerebral abscess formation, cysticercosis or residuals after congenital cytomegalovirus infections. Intracerebral cystic defects may be caused by inflammatory central nervous system (CNS) diseases, such as multiple sclerosis as well as by mitochondriopathies, leukodystrophy, electrolyte disturbances or osmotic demyelination syndrome or brain infarctions, e.g. after lacunar infarctions or as encephalomalacic changes after severe traumatic brain injury.

RADIOLOGICAL STANDARD PROCEDURES

In addition to the radiological findings of cysts in magnetic resonance imaging (MRI) or in computed tomography (CT), the localization, patient age, patient medical history and laboratory diagnostics are helpful for the differential diagnostics.

METHODICAL INNOVATION

In addition to the morphological assessment, advanced MRI techniques, such as diffusion-weighted imaging for epidermoids or the use of MR spectroscopy, can provide valuable information for the differential diagnosis.

PERFORMANCE/ASSESSMENT

Intracranial cysts can be subdivided into intraventricular and periventricular cysts, intra-axial cysts and cysts in the external fluid-filled spaces. Associated tumor nodules and the contrast medium behavior of the cyst walls and/or associated soft tissue components as well as the reaction of the adjacent parenchyma are helpful for the diagnosis and assessment.

Acute triventricular hydrocephalus caused by choroid plexus cysts: a diagnostic and neurosurgical challenge

OBJECTIVE

Intraventricular choroid plexus cysts are unusual causes of acute hydrocephalus in children. Radiological diagnosis of intraventricular choroid plexus cysts is difficult because they have very thin walls and fluid contents similar to CSF and can go undetected on routine CT studies.

METHODS

This study reports the authors' experience with 5 patients affected by intraventricular cysts originating from the choroid plexus. All patients experienced acute presentation with rapid neurological deterioration, sometimes associated with hypothalamic dysfunction, and required urgent surgery. In 2 cases the symptoms were intermittent, with spontaneous remission and sudden clinical deteriorations, reflecting an intermittent obstruction of the CSF pathway.

RESULTS

Radiological diagnosis was difficult in these cases because a nonenhanced CT scan revealed only triventricular hydrocephalus, with slight lateral ventricle asymmetry in all cases. MRI with driven-equilibrium sequences and CT ventriculography (in 1 case) allowed the authors to accurately diagnose the intraventricular cysts that typically occupied the posterior part of the third ventricle, occluding the aqueduct and at least 1 foramen of Monro. The patients were managed by urgent implantation of an external ventricular drain in 1 case (followed by endoscopic surgery, after completing a diagnostic workup) and by urgent endoscopic surgery in 4 cases. Endoscopic surgery allowed the shrinkage and near-complete removal of the cysts in all cases. Use of neuronavigation and a laser were indispensable. All procedures were uneventful, resulting in restoration of normal neurological conditions. Long-term follow-up (> 2 years) was available for 2 patients, and no complications or recurrences occurred.

CONCLUSIONS

This case series emphasizes the necessity of an accurate and precise identification of the possible causes of triventricular hydrocephalus. Endoscopic surgery can be considered the ideal treatment of choroid plexus cysts in children.

Surgery for intracranial arachnoid cysts in children-a prospective long-term study

PURPOSE

Intracranial arachnoid cysts are cystic malformations found in both adults and children. While many are asymptomatic, some cause symptoms and warrant surgical treatment. In this prospective population-based study, we aimed to study the short- and long-term outcome after surgical intervention in children with arachnoid cysts referred to our centre.

METHODS

Twenty-seven pediatric patients (13 f. 14 m, mean age 9.4 years) with de novo cysts were consecutively included during a 5-year period. The presenting symptoms were headache (n = 12), balance disturbance and dizziness (n = 6), seizures (n = 6), hydrocephalus (n = 5), and macrocephaly (n = 1). Twenty-two patients underwent surgical treatment with either microsurgical (n = 17) or endoscopic fenestration (n = 5) of the cyst wall. Cyst volume was measured with OsiriX® software pre- and postoperatively. Short-term and long-term follow-up of all patients was conducted 3 months and 8.6 years (7-10.5 years) postoperatively.

RESULTS

Three months after surgery, 59 % of the patients were improved regarding at least one major complaint, and average cyst volume was reduced to 33.3 ml (0-145 ml). At the long-term follow-up of 8.6 years, 77 % of the patients were improved regarding at least one symptom but subjective symptoms remained in 59 %. There was no permanent postoperative morbidity. We found no association between radiological reduction of cyst volume and clinical improvement.

CONCLUSION

Our findings support a restrictive attitude to surgery for intracranial arachnoid cysts, in the absence of objectively verified symptoms and signs or obstruction of CSF pathways.