Imaging of posterior fossa epidermoid tumors

Intracranial Epidermoid Cyst: A Volumetric Study of a Surgically Challenging Benign Lesion

BACKGROUND

Intracranial epidermoid cysts are rare, benign tumors. Nevertheless, the microsurgical removal of these cysts is challenging. This is due to their capacity to adhere to the neurovascular tissue, as well as the associated difficulties in microsurgically peeling off their capsular wall hidden in dead angles. To better understand the rate of recurrence after surgical intervention, we have performed preoperative and postoperative volumetric analysis of epidermoid cysts, allowing the estimation of their growth rate after resection.

METHODS

Imaging data from 22 patients diagnosed and surgically treated for an intracranial epidermoid cyst between 2000 and 2022 were retrospectively collected from 2 European neurosurgical centers with microsurgical expertise. Volumetric analysis was performed on magnetic resonance imaging data.

RESULTS

Average cyst volume at diagnosis, before any surgery, measured in 12 patients was 28,877.6 ± 10,250.4 mm3 (standard error of the mean [SEM]). Estimated growth rate of incompletely resected epidermoids after surgery was 1,630.05 mm3 ± 729.95 (SEM). Assuming linear growth dynamics and normalizing to postoperative residual volume, the average postoperative growth rate corresponded to 61.5% ± 34.3% (SEM) of the postoperative residual volume per year. We observed signs of recurrence during a radiologic follow-up period of 6.0 ± 2.8 years (standard deviation) in more than 50% of our patients.

CONCLUSIONS

Due to their slow-growing nature, epidermoid cysts can often reach a complex multicompartmental size before resection, even in young patients, thus requiring complex approaches with challenging capsular resection, which implies a high risk of nerve and vascular injury per se. Tumor recurrence may be predicted on the basis of postoperative volumetry.

Compressive lesions of the head and neck: Common and uncommon must-know entities

There are many lesions that cause compression of nerves and vessels in the head and neck, and they can often be overlooked in the absence of adequate history or if not suspected by the radiologist. Many of these lesions require a high index of suspicion and optimal positioning for imaging. While a multimodality approach is critical in the evaluation of compressive lesions, an MRI utilizing high-resolution (heavily weighted) T2-weighted sequence is extremely useful as a starting point. In this review, we aim to discuss the radiological features of the common and uncommon compressive lesions of the head and neck which are broadly categorized into vascular, osseous, and miscellaneous etiologies.

The cerebellum plays more than one role in the dysregulation of appetite: Review of structural evidence from typical and eating disorder populations

OBJECTIVE

Dysregulated appetite control is characteristic of anorexia nervosa (AN), bulimia nervosa (BN), and obesity (OB). Studies using a broad range of methods suggest the cerebellum plays an important role in aspects of weight and appetite control, and is implicated in both AN and OB by reports of aberrant gray matter volume (GMV) compared to nonclinical populations. As functions of the cerebellum are anatomically segregated, specific localization of aberrant anatomy may indicate the mechanisms of its relationship with weight and appetite in different states. We sought to determine if there were consistencies in regions of cerebellar GMV changes in AN/BN and OB, as well as across normative (NOR) variation.

METHOD

Systematic review and meta-analysis using GingerALE.

RESULTS

Twenty-six publications were identified as either case-control studies (nOB  = 277; nAN/BN  = 510) or regressed weight from NOR data against brain volume (total n = 3830). AN/BN and OB analyses both showed consistently decreased GMV within Crus I and Lobule VI, but volume reduction was bilateral for AN/BN and unilateral for OB. Analysis of the NOR data set identified a cluster in right posterior lobe that overlapped with AN/BN cerebellar reduction. Sensitivity analyses indicated robust repeatability for NOR and AN/BN cohorts, but found OB-specific heterogeneity.

DISCUSSION

Findings suggest that more than one area of the cerebellum is involved in control of eating behavior and may be differentially affected in normal variation and pathological conditions. Specifically, we hypothesize an association with sensorimotor and emotional learning via Lobule VI in AN/BN, and executive function via Crus I in OB.

Correlation of radiological features of white epidermoid cysts with histopathological findings

Epidermoid cysts are benign congenital extra-axial lesions commonly found in the posterior fossa. These lesions have a characteristic imaging appearance on computed tomography (CT) scan and magnetic resonance imaging (MRI), but occasionally they may exhibit atypical radiological features, showing unusual hyperintensity on T1-weighted images (T1WI). Currently, such atypical appearance is referred to as white epidermoid. We present the imaging features of 5 cases of white epidermoid cyst and discuss the possible underlying etiology of this unusual radiological appearance. We retrospectively searched our electronic radiology database from January 2005 to December 2015 for all intracranial epidermoid cysts, which were confirmed either by typical MRI appearance or histopathological examination. All white epidermoid cases were evaluated with non-enhanced CT scan and multisequential MRI. Histopathological correlation was carried out in four white epidermoid cases. A total of 61 patients with epidermoid cyst were found, of those 5 (8%) were considered white epidermoids. These consisted of 3 females and 2 males, ranging in age between 31–63 years (average age was 51.8 years). Three patients had lesions located in the posterior fossa. The 2 other patients had lesions in the suprasellar region, with extension to the right middle cranial fossa in one. All 5 lesions were hyperdense on CT scan and hyperintense on T1WI. One patient demonstrated evidence of transformation of a classic epidermoid to a white epidermoid after partial resection. Histopathologically, cholesterol clefts were seen in 3 epidermoid cysts, each which also showed microcalcifications, proteinaceous material or melanin. Hemorrhage was demonstrated in one additional lesion. White epidermoid cyst is an unusual intracranial lesion that should be considered when encountered with an extra-axial T1 hyperintense lesion. The cause of this hyperintensity is not clearly understood, but the presence of cholesterol, microcalcifications, proteinaceous content and rarely hemorrhage or melanin may be contributing factors.

CT cisternography to visualize epidermoid tumors for stereotactic radiosurgery treatment planning

The visualization of intracranial epidermoid tumors is often limited by difficulties associated with distinguishing the tumor from the surrounding cerebrospinal fluid using traditional computed tomography (CT) or magnetic resonance imaging (MRI) modalities. This report describes our experience using CT cisternography to visualize intracranial epidermoid tumors in three illustrative cases. CT cisternography of the epidermoid tumor provides more clarity and precision compared to traditional neuroimaging modalities. We demonstrate the feasibility of using CT cisternography to produce high-resolution images with well-defined tumor margins that can be used effectively for precise SRS treatment planning.

Role of diffusion-weighted imaging in differentiation between posterior fossa brain tumors

Background

Diffusion-weighted imaging (DWI) is an imaging modality using multi-section single-shot spin echo planar imaging (EPI) sequence which is extremely sensitive for detection of water motion within intra, extra, and transcellular regions. This character is important to differentiate between brain tumors either low (benign) or highly (malignant) cellular tumors.

Objective

To evaluate the role of DWI and apparent diffusion coefficient (ADC) in evaluation and differentiation between different brain posterior fossa tumors in children and adults.

Patients and methods

The study included 34 patients with different brain posterior fossa tumors for evaluation by conventional MRI (using 1.5 T MRI PHILIPS Achieva 2.1 Best Netherland) and DWI.

Results

Our study showed that mean ADC values were significantly different between the four groups of posterior fossa tumors in children: juvenile pilocytic astrocytoma (JPA), medulloblastoma, ependymoma, and brain stem glioma while mean ADC values were not significantly different between posterior fossa tumors in the adult group. Regions of interest were manually positioned, and all values were automatically calculated and expressed in 10−3 mm2/s.

Conclusion

DWI is an ideal additional imaging technique, which is a rapid, easy, non-invasive imaging modality, with no contrast injection needed. It has been widely applied in the differentiation between posterior fossa brain tumors and in the diagnosis of various intracranial diseases.

Diffusion MR Imaging in the Head and Neck: Principles and Applications

Diffusion imaging is a functional MR imaging tool that creates tissue contrast representative of the random, microscopic translational motion of water molecules within human body tissues. Long considered a cornerstone MR imaging sequence for brain imaging, diffusion-weighted imaging (DWI) increasingly is used for head and neck imaging. This review reports the current state of diffusion techniques for head and neck imaging, including conventional DWI, DWI trace with apparent diffusion coefficient map, diffusion tensor imaging, intravoxel incoherent motion, and diffusion kurtosis imaging. This article describes background physics, reports supportive evidence and potential pitfalls, highlights technical advances, and details practical clinical applications.

Conservative management of a fourth ventricular epidermoid in a patient with Gardner syndrome

Gardner Syndrome is a rare disease with clinical manifestations of familial intestinal polyposis with osteomas. Cutaneous and subcutaneous lesions are common and epidermoid cyst is a characteristic dermatologic finding. This case report presents a novel finding of an intracranial epidermoid situated in the fourth ventricle in a patient with Gardner Syndrome. This intracranial epidermoid has been followed with sequential magnetic resonance imaging (MRI) for 10 years with progressive growth of the lesion. This suggests the conservative management is an option in patients with an enlarging epidermoid cyst in the fourth ventricle.

Plain language summary

Non-operative treatment of a cyst in the brain in a syndrome called Gardner syndrome. What is Gardner syndrome? Gardner syndrome is a rare disease and form of familial adenomatous polyposis (FAP) that is characterized by multiple small growths of cells (polyps) in the colon and various types of tumors, both noncancerous (benign) and cancerous (malignant). It is caused by changes (mutations) in the APC gene. Abnormal changes on the skin and under the skin are common as well as growths called epidermoid cysts. The cysts develop when cells that are meant to become skin, hair, and nails (epithelial cells) are trapped among the cells that form the brain. Epidermoid brain cysts may be diagnosed by magnetic resonance imaging (MRI) and computerized tomography (CT) scans. Typical treatment usually involves surgery. What was the aim of this case report? To present a different management strategy for patients with Gardner Syndrome with epidermoid brain cysts. How was this patient treated? This patient is the first patient with Gardner Syndrome with a very rare epidermoid brain cyst reported to be treated in a conservative manner.The patient was monitored for 10 years with regular MRI scans and the cyst continued to grow over this time.Despite this growth the patient has shown no signs of a buildup of fluid in the cavities deep within the brain (called hydrocephalus).The patient experienced nonfocal headaches, which were relieved with medication so doctors decided not to surgically remove the cyst. Why is this case important? Conservative management of epidermoid brain cysts in Gardner patients has not been reported before. This case report shows that conservative management may be an alternative option for patients with a growing epidermoid cyst in the fourth ventricle of the brain. Conservative treatment is designed to avoid invasive treatments or surgery and provides a different option for patients who are unable to have surgery.

Mixed Signal Intensity on Preoperative T1 MRI Might be Associated with Delayed Postoperative Hemorrhage in Patients with Intracranial Epidermoid Cyst

OBJECTIVE

Delayed postoperative hemorrhage (DPOH) was a severe postoperative complication after intracranial epidermoid cyst (EC) surgery. This study was designed to investigate possible clinical data and image features related to DPOH in patients with EC.

METHODS

We retrospectively investigated 186 cases of EC, and 8 cases presented an appearance of DPOH. Preoperative magnetic resonance imaging (MRI) and clinical data (age, sex, chief surgeon, tumor size, tumor location, and degree of resection) were reviewed and analyzed. The Student t test and the χ² test were used, and statistical significance was defined as P < 0.05.

RESULTS

A total of 8 patients suffered from DPOH. Seven patients (87.5%) with DPOH showed atypical mixed signal intensity on preoperative T1 MRI compared with typical low intensity in another DPOH case. Only 1 case of mixed signal intensity on T1 MRI was found in 178 patients without DPOH. The mixed signal intensity on preoperative T1 MRI was highly related to DPOH and mortality (both P < 0.001). There was no significant difference in other relative clinical data between patients with or without DPOH.

CONCLUSIONS

Mixed signal intensity on preoperative T1 MRI might be associated with DPOH in patients with EC. The surgeon should pay more attention to this rarely atypical imaging before surgery. Further observations are necessary to illustrate the relationship between mixed signal intensity and DPOH in EC and to guide reasonable therapy.

Surgical Management of Intracranial Giant Epidermoid Cysts in Adult: A Case-Based Update

Epidermoid cysts (ECs) are benign and slow-growing lesions that account for about 0.2%-2% of all intracranial tumors. Symptoms appear slowly and tumors may have already grown to giant proportions when patients receive their first diagnosis. The optimal treatment for ECs is surgical removal, which includes the total resection of the entire capsule of the lesion in order to minimize the risk of malignant transformation associated with partial removal. However, considering the giant size that the ECs can reach at the time of the diagnosis, and their adherence to the surrounding structures, the risks and benefits of total versus subtotal resections in the short- and long-term patients' outcome are still under debate. Here, we report a case of an extensive giant EC and offer a discussion of its characteristics, surgical management, and postoperative outcome, taking a cue to argue about the recent literature based in the latest case studies.

Cerebellar Vermian Epidermoid Tumor: A Report of 2 Cases

BACKGROUND

Epidermoid tumors are rare, benign slow-growing congenital tumors, most frequently located in the cerebellopontine angle of the intracranial cavity. They usually grow to a large size before patients become symptomatic. Although these tumors are amenable to surgery, their adherence to neurovascular structures poses a surgical challenge that results in subtotal resection, thus increasing the risk of recurrence.

CASE DESCRIPTION

We report 2 adult patients whose imaging studies revealed epidermoid tumors located in the cerebellar vermis, an uncommon site for such tumors. The patients presented with variable symptomatology. We highlight the imaging features and challenges of surgery. Both patients had good outcomes, with resolution of symptoms and neurologic deficits.

CONCLUSIONS

A safe complete excision of epidermoid tumor and its capsule is possible with a good understanding of their clinical and radiologic features and a high index of suspicion. To the best of our knowledge, this is the first report of cerebellar vermian epidermoid tumors from sub-Saharan Africa.

A Frontal Giant Intradiploic Giant Pearl (Epidermoid Cyst) With Intracranial and Extracranial Extension: A Rare Entity

Craniofacial epidermoid cysts are rare tumors representing 0.2%-1% of all the intracranial tumors. Intradiploic variants account for 25% of these cysts. These cysts are benign, slow-growing, congenital tumors derived from ectodermal remnants misplaced during embryogenesis. Mean age at presentation of these lesions is 40 years; epidermoid cysts are typically asymptomatic (Toglia JU, Netsky MG, Alexander E Jr. Epithelial (epidermoid) tumors of the cranium. Their common nature and pathogenesis. J Neurosurg 1965;23:384-93). Giant extradural epidermoid cysts with profound deformation of the brain and extensive lytic skull lesions may allow a normal life without any significant neurological deficits. Computed tomography scan and magnetic resonance imaging play an important role in the diagnosis of the lesion and management protocol. Histologically, epidermoid cysts are lined by stratified squamous epithelium and are filled with anucleatic keratin (Hao S, Tang J, Wu Z, Zhang L, Zhang J, Wang Z. Natural malignant transformation of an intracranial epidermoid cyst. J Formos Med Assoc 2010;109:390-6). Complete removal of the cyst along with its capsule is the treatment of choice. Recurrences of intradiploic epidermoid cyst have been reported. Here, we report a case of 14-year-old girl presenting with a giant frontal intradiploic epidermoid cyst with an intracranial and extracranial extension without any neurological deficits. Bifrontal craniotomy was performed and cyst was excised in toto.

Epidermoid cyst with unusual magnetic resonance characteristics and spinal extension

Intracranial epidermoid cysts are generally located in the cerebellopontine and parasellar areas and appear hypo-dense on computed tomography and hypo-intense on T1-weighted magnetic resonance imaging. We report a case of an unusual epidermoid cyst of the cerebellopontine angle extending into the upper cervical canal that appeared hyper-dense on computed tomography scanning, hyper-intense on T1-weighted magnetic resonance (MR) images, and hypo-intense on T2-weighted MR images.

Giant intracranial epidermoids: is total removal feasible?

OBJECT

Epidermoid tumors arise from misplaced squamous epithelium and enlarge through the accumulation of desquamated cell debris. Optimal treatment consists of total removal of the capsule; therefore, giant and multicompartmental tumors are particularly challenging. A conservative attitude in handling the tumor capsule is common given concerns about capsule adherence to neurovascular structures, and thus the possibility of recurrence is accepted with the intent of minimizing complications. This study focuses on the outcome of surgery in patients with giant epidermoid tumors for which total capsule removal was the aim.

METHODS

The authors conducted a retrospective analysis of all patients with giant epidermoid tumors treated by the senior author (O.A.), who pursued total removal of the capsule through skull base approaches. Patients were divided into 2 groups: one including patients with de novo tumors and the other consisting of patients who presented with recurrent tumors.

RESULTS

Thirty-four patients had undergone 46 operations, and the senior author performed 38 of these operations in the study period. The average tumor dimensions were 55 × 36 mm, and 25 tumors had multicompartmental extensions. Total removal of the tumor and capsule was achieved with the aid of the microscope in 73% of the 26 de novo cases but in only 17% of the 12 recurrent tumor cases. The average follow-up among all patients was 111 months (range 10–480 months), and the average postsurgical follow-up was 56.8 months (range 6–137 months). There were 4 recurrences in the de novo group, and every case had had a small piece of tumor capsule left behind. One patient died after delayed rupture of a pseudoaneurysm. In the de novo group, the average preoperative Karnofsky Performance Scale (KPS) score was 71.42%, which improved to 87.14% on long-term follow-up. In the group with recurrences, the KPS score also improved on long-term follow-up, from 64.54% to 84.54%. In the de novo group, 3 cases (11.5%) had permanent cranial nerve deficits, and 4 cases (15.4%) had a CSF leak. In the recurrence group, 3 cases (25%) had new, permanent cranial nerve deficits, and 1 (8.3%) had a CSF leak. Two patients in this group developed hydrocephalus and required a shunt.

CONCLUSIONS

Total removal of the capsule of giant epidermoid tumors was achieved in 73% of patients with de novo tumors and was associated with improved function, low morbidity and mortality, and a lower risk of recurrence. Surgery in patients with recurrent tumors was associated with higher morbidity and persistence of the disease.

Transpterygoid stent placement for management of a recurrent infratemporal fossa epidermoid cyst: a technical note

Epidermoid cysts (ECs) are benign congenital cysts that typically develop from misplaced stratified squamous epithelium during neural tube closure. They are most commonly encountered in the cerebellopontine angle, the fourth ventricle, and the region of the sella turcica. Recurrence of an EC or regrowth of residual components following surgery is known to occur, but the exact incidence is not defined. Repeat surgical removal is generally considered but may be complicated by significant morbidity. We present a novel endoscopic method by which to manage a recurrent EC of the infratemporal fossa using a silastic stent through a transpterygoid approach that permits periodic drainage of recurrent cyst material in the outpatient setting with minimal morbidity.

Intracranial epidermoid tumor; microneurosurgical management: An experience of 23 cases

OBJECTIVES

An intracranial epidermoid tumor is relatively a rare tumor, accounting for approximately 0.1% of all intracranial space occupying lesions. These are also known as pearly tumor due to their pearl like appearance. In this series, the localization of the tumor, presenting age and symptoms, imaging criteria for diagnosis, surgical management strategy with completeness of excision and overall outcome were studied prospectively. Here, we report our short experience of intracranial epidermoid as a whole.

MATERIALS AND METHODS

Between January 2006 to December 2010, 23 cases of intracranial epidermoid were diagnosed preoperatively with almost certainty by computed tomography (CT) and magnetic resonance imaging (MRI) of brain in plain, contrast and other relevant studies. All of them underwent operation in Dhaka Medical College Hospital and in some Private Hospital in Dhaka, Bangladesh. All patients were followed-up routinely by clinical examination and neuroimaging. Average follow-up was 39 (range-71-11months) months. Patients of the series were prospectively studied.

RESULTS

Supratentorial epidermoids were 04 cases and infratemporal epidermoids were 19 cases. Clinical features and surgical strategy varies according to the location and extension of the tumors. Age range was 19-71 years (37.46 years). Common clinical features were headache, cerebellar features, seizure, vertigo, hearing impairment and features of raised intracranial pressure (ICP). Investigation was CT scan or/+ MRI of brain in all cases. Pre-operative complete excision was 20 cases, but post-operative images showed complete excision in 17 cases. Content of tumor was pearly white/white material in all cases except one, where content was putty material. Re-operation for residual/recurrent tumor was nil. Complications included pre-operative mortality one case, persisted sixth nerve palsy in one case, transient memory disturbance one case, and extra dural hematoma one case. One senior patient expired three months after the operation from spontaneous intracerebral hemorrhage. Rest of the patients were stable and symptom/s free till last follow-up.

CONCLUSION

In the management of such tumors, one should keep in mind that an aggressive radical surgery carrying a high morbidity and mortality and a conservative subtotal tumor excision is associated with a higher rate of recurrence, but earlier diagnosis and complete excision or near total excision of this benign tumor can cure the patient with the expectation of normal life.

Unusual complications of a benign tumour - our experience with midline posterior fossa epidermoids

Epidermoids of the brain are uncommon benign tumours. Their midline posterior fossa location is exceedingly rare. Fifteen patients with this condition were operated during a 14-year period. Majority of the patients presented in their middle age with mean duration of symptoms of 10 months. Gait imbalance was the commonest symptom observed. Seven patients had features suggestive of raised intracranial tension. Computed tomography scanning showed typical hypodense lesions. On MRI, tumours were hypo-intense on T1 weighted images and hyper-intense on T2 weighted images. All patients underwent microsurgical excision. We encountered certain complications in the post-operative period. This prompted us for a review of our case material and literature and is the basis of the present article. Implications of these findings are discussed.

[Epidermoid cyst of the cisterna magna and the fourth ventricle: Report of four cases]

INTRODUCTION

Epidermoid cyst is a congenital and benign tumor, developed from ectodermal inclusion. These cysts occur very rarely in the cisterna magna and the fourth ventricle.

OBJECTIVE

To report four cases of epidermoid cyst of the cisterna magna and the fourth ventricle in the light of the data of literature.

PATIENTS AND METHODS

We report a retrospective study of four cases of epidermoid cysts of the cisterna magna and the fourth ventricle. The data was collected from January 2000 to December 2006 from to series of 18 cases of epidermoid cysts of posterior cranial fossa (14 cases were localised at the cerebellopontine angle). All the patients had a physical examination and a complete neuroradiological imagery. The treatment was surgical. The follow-up was at least 9 months.

RESULTS

There were two men and two women. The mean age was 47.75 years. All patients presented with cerebellar syndrome. Three patients had intracranial hypertension. Neuroradiological explorations showed a cystic lesion developed in the cisterna magna in two cases, in the fourth ventricle in one case and in the two locations in one case. Two patients had hydrocephalus. All patients had surgery with a posterior approach and one patient had first ventriculoperitoneal shunt. The diagnosis was confirmed by histological examination. Postoperatory outcome was favourable in all cases. One patient developed bilateral chronic subdural hematoma, which was surgically removed. A long time follow-up was good in all cases.

CONCLUSION

Epidermoid cysts are characterized by a long evolution. The diagnosis is relatively characteristic in the imagery. The prognosis was favourable with a complete surgical resection.

Clinical characteristics and diagnostic imaging of epidermoid tumors

Epidermoid tumors are rare, benign congenital lesions which typically present between the third and fifth decades of life. They are thought to originate from ectodermal cells misplaced during neural tube formation and separation. While epidermoids may present anywhere in the cranial vault, they are characteristically located intradurally and in a paramedian position within the cerebellopontine angle and parasellar regions. Although imaging results may vary depending upon cystic content, CT scanning generally reveals a well-circumscribed, nonenhancing, lobulated, hypodense mass. They are hypointense on T1-weighted MRI, and hyperintense on T2-weighted MRI, diffusion-weighted imaging and fluid-attenuated inversion recovery sequences. The use of appropriate neuroimaging should be utilized to differentiate epidermoids from other intracranial lesions. While gross total resection of these tumors is the definitive treatment to prevent recurrence and aseptic meningitis, a subtotal resection may be necessary to preserve neurological function.

Posterior fossa epidermoid cysts presenting with unusual radiological appearances--two case reports

Intracranial epidermoid cysts generally appear as hypodense on computed tomography (CT), hypointense on T(1)-weighted magnetic resonance (MR) imaging, and hyperintense on diffusion-weighted MR imaging. We report two cases of posterior fossa epidermoid cysts with unusual radiological features. A 49-year-old male presented with facial dysesthesia and a 12-year-old male presented with diplopia and internuclear ophthalmoplegia. CT of both cases revealed hyperdense lesions. MR imaging showed the first case as hypointense in the posterior part and hyperintense in the anterior part of the tumor on diffusion-weighted imaging, and the second case as hyperintense on diffusion-weighted and T(1)-weighted MR imaging. Surgical exploration revealed that the tumors consisted of creamy materials, instead of the usual semi-solid or flaky texture in epidermoid cysts. Xanthochromic serous fluid was also contained in the superoposterior half of the cyst of the first case. These unusual contents of the cyst may be responsible for the unusual neuroimaging findings. Histological examination showed both cysts were lined with stratified squamous epithelium and contained keratinaceous materials. Therefore, epidermoid cysts can occasionally present with unusual radiological characteristics giving rise to a diagnostic pitfall.

Multiple fractures involving the orbit and incidental finding of large fourth ventricular epidermoid

Epidermoid tumors located in the fourth ventricle are exceedingly rare, and the patients usually present with headaches, vertigo, and/or disequilibrium. We discuss the management of orbital floor and lateral wall fracture in a patient who was also incidentally diagnosed to have a large fourth ventricular epidermoid cyst. Although because of their availability and ease of use many allografts have been described, when available, the use of similar membranous bone of equivalent thickness makes the bone graft ideally suited for reconstruction of the orbital floor.

Adjacent epidermoid cyst and primary central nervous system lymphoma: case report

BACKGROUND

Except for cases with radiotherapy or phacomatosis, multiple primary brain tumors of different histologic types are rare. The authors report the association of an epidermoid cyst and a primary CNS lymphoma.

CASE DESCRIPTION

A 66-year-old man with a 20-year history of gait disturbance was admitted because of recently worsening symptoms. Magnetic resonance imaging showed an abnormal mass in the posterior fossa. The mass lesion had the appearance of a cystic tumor with a large mural nodule. Gross total removal of the tumor was performed. Histologic examination disclosed the cystic portion to be an epidermoid, whereas the nodular portion exhibited the histologic and immunohistochemical features of a malignant lymphoma. The lymphoma cells were shown to harbor EBV by in situ hybridization.

CONCLUSIONS

To our knowledge, this is the first report of the coexistence of an epidermoid cyst and primary CNS lymphoma. When the lesions are adjacent, a definite preoperative diagnosis can be difficult. Epstein-Barr virus-associated CNS lymphoma is rare among the immunologically normal population. The possible pathogenesis for the coexistence of these 2 tumors is discussed.

Infratentorielle Tumoren

This article gives an overview concerning the typical infratentorial tumors of adults.

Epidermoid cysts of the cerebellopontine angle with extension into the middle and anterior cranial fossae: surgical strategy and review of the literature

Epidermoid cysts are tumours, which contain keratin, cellular debris and cholesterol, and lined with stratified squamous epithelium. Clinically, epidermoid cysts behave like benign, slow-growing lesions. We present a 63 year-old man with a 6-month history of right periorbital pain and hypaesthesia in the area of the first and second branch of the trigeminal nerve. MRI revealed an epidermoid cyst of the cerebellopontine angle extending into the middle and anterior cranial fossae. Radical surgical removal of epidermoid cysts should be attempted, but a less aggressive surgical strategy should be considered if there is strong adherence to the surrounding brain tissue, particularly in eloquent areas. In this case, complete tumour removal was achieved via a suboccipital retrosigmoid approach.

Hyperdense intracranial epidermoid cysts: a study of 15 cases

BACKGROUND

Although intracranial epidermoid cysts generally appear as hypodense lesions on CT scans, occasionally, they may appear hyperdense, making diagnosis difficult. The aim was to study clinical features and possible pathogenesis of hyperdense intracranial epidermoid cysts (HIECs).

METHODS

Fifteen patients with HIECs were surgically treated in our department during a 21-year period (1985 up to 2005). We reviewed each patient's clinical records, radiological findings, operative reports, and pathological examinations, along with a review of the literature.

FINDINGS

The incidence of HIECs in our series was approximately 3.02%, with female predominance. The average age was 32 years and the average duration of complaints was nine months. The most common location was the parasellar area (6 cases), followed by cerebellum (4 cases), clival region (3 cases), cerebello-pontine angle (1 case) and lateral ventricle (1 case). Gross-total excision of the tumor was achieved in ten patients (66.7%). Four (26.7%) patients underwent subtotal resection; and one (6.6%) patient underwent partial resection. Aseptic meningitis that occurred postoperatively in two cases was controlled by lumbar drainage.

CONCLUSIONS

Recurrent leakage of the irritating cyst contents and subsequent chemical inflammatory response may be responsible for the high-density on CT scans and the cystic nature. A correct histological diagnosis is important because, in contrast to typical ECs and other lesions, HIECs are more prone to spread intra-operatively and result in severe aseptic meningitis.