Epithelial (epidermoid) tumors of the cranium. Their common nature and pathogenesis

Beyond the otoscope: an imaging review of congenital cholesteatoma

Congenital cholesteatoma (CC) is a non-neoplastic lesion of keratin debris lined by epithelium found in the temporal bone. It is the lesser-known sibling of the acquired cholesteatoma and may be classified as congenital middle ear cholesteatoma and congenital petrous bone cholesteatoma. The incidence is rising, probably owing to increased recognition and advances in imaging modalities. Cone beam CT provides detailed anatomical information, highlighting quadrant location, ossicular involvement, and mastoid extension. MRI aids in lesion characterization and detection of complications. The classification systems for congenital middle ear and petrous bone cholesteatoma are helpful in the preoperative workup and have a role in predicting postoperative recurrence rates. Management almost invariably involves surgical intervention aimed at preserving middle and inner ear function. Follow-up of CC is mainly based on MRI together with otoscopic examination. Non-echo planar diffusion-weighted imaging, especially, has proven essential for detecting residual disease. This review article emphasizes the significance of imaging in the timely diagnosis and management of CCs. CLINICAL RELEVANCE STATEMENT: This article underscores the crucial role of imaging for prompt detection, preoperative assessment, and postoperative follow-up of CCs, a condition with rising incidence associated with potentially severe complications. KEY POINTS: Timely diagnosis of CCs is imperative for avoiding complications. Imaging is key in detection, preoperative evaluation, and postoperative management. Cone Beam CT and non-echo planar DWI represent state-of-the-art imaging techniques.

Epidermoid Cyst of the Brainstem in 3-Year-Old Child: A Rare Case Report

Epidermoid cysts are infrequent lesions occupying the intracranial space, comprising approximately 1-2% of all intracranial tumors. Brainstem epidermoids are exceptionally uncommon in children; up until now, only a few scattered case reports have been documented in the literature regarding this unique location. These cysts commonly arise from the inclusion of ectodermal elements during neural tube closure. Complete excision of these cysts is challenging due to their close proximity and adherence to the brainstem, which makes it difficult to achieve. As a result, recurrence of the cysts is not uncommon. We have reported a rare case of a 3-year-old with a 5-month history of progressive headache, imbalance while walking and progressive weakness in his right upper limb and lower limb along with difficulty in swallowing. On MRI Brain imaging study he had a pre-pontine epidermoid with intra-axial extension in the pons. The patient underwent retro-sigmoid/suboccipital craniotomy and microsurgical excision of the tumor, including the tumor capsule. After completing the surgery, the cavity was irrigated using a solution containing hydrocortisone and Ringer lactate to prevent the occurrence of aseptic meningitis. In the postoperative, the patient recovered without any complications, as all symptoms showed immediate improvement, and the lower cranial nerves returned to normal functioning.

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

OBJECTIVE

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 25 years after initial resection. Additionally, we performed a systematic review including 94 studies reporting intracranial EDC to SCC transformation.

METHODS

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.

RESULTS

The overall median time to transformation was 60 months (95% confidence interval {CI}, 12-96). Transformation time was significantly shorter in the no surgery group (10 months, 95% CI undefined) versus the other 2 groups (60 months, 95% CI, 12-72 in surgery only and 70 months, 95% CI, 9-180 in surgery + adjuvant therapy group, both P < 0.01). Overall survival was significantly longer in the surgery + adjuvant therapy group (13 months, 95% CI, 9-24) versus the other 2 groups (3 months, 95% CI, 1-7 in surgery only and 6 months, 95% CI, 1-12 in the no surgery group, both P < 0.01).

CONCLUSIONS

We report a rare case of delayed malignant transformation of an intracranial EDC to SCC, occurring nearly 25 years 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.

Posterior Fossa Midline Epidermoid Tumors: Role of the Inferior Medullary Velum and a Proposed New Imaging Classification

BACKGROUND

Posterior fossa midline epidermoid tumors (PFMETs) include the epidermoid tumors of the cisterna magna (CM) and fourth ventricle (FV).

OBJECTIVE

To report tumor epicenter-based classification of PFMETs and its clinical and surgical implications with outcome.

METHODS

On retrospective analysis of operated cases of intracranial epidermoid tumors, 19 (N = 19) patients having tumor epicenter within FV, CM, or both were included. Cerebellopontine and prepontine cistern epidermoid were excluded. Tumor location was decided based on preoperative MRI and intraoperative findings. Major complication was defined as new onset or worsening of cranial nerve (CN) deficit, sensory motor impairment, or tracheostomy.

RESULTS

The mean (±SD) age of the patients was 42.0 ± 11.6 years (range 25-61 years), with no sex predilection (male:female: 1:0.9). The most common symptoms were cerebellar dysfunction, headache, vomiting, and diplopia. Common CNs affected were VII, V, lower cranial nerve, and VI. The PFMETs were classified based on tumor epicenter as type 1 (tumor epicenter in CM, n = 4/21.1%), type 2 (FV, n = 5/26.3%), and type 3 (involved CM and FV, n = 10/52.6%). Type 2 tumors had a higher incidence of raised intracranial pressure and only facial nerve palsy as preoperative CN deficit. Type 1 tumors had the least incidence of postoperative major complications. Type 3 tumors were the largest and had a greater incidence of brainstem adhesion and postoperative complications. The tumor size, duration of symptoms, and patient age were higher in patients with brainstem adhesion (5.3 ± 1.0 cm, 21 ± 16 months, 44.1 ± 9.2 years) as against its absence (4.8 ± 1.3 cm, 11.2 ± 7.3 months, 38.2 ± 11.7 years). Inferior medullary velum and tela choroidea have a critical role in tumorogenesis, tumor extension, and brainstem adhesion.

CONCLUSION

PFMETs can be classified into 3 subtypes based on tumor epicenter having clinical and surgical implications. Less aggressive dissection and near total excision in the presence of brainstem adhesion yield favorable outcomes.

Radio-pathological characteristics of malignant transformation of an epidermoid cyst in the cerebellopontine angle: A case report

Background

Intracranial epidermoid cysts are rare congenital neoplasms that are clinically indolent and histologically benign. They rarely show malignant transformation, and several such cases have been reported. Some radiological features that suggest malignant transformation have been reported. However, histopathological features that indicate a high risk of malignant transformation have not been reported to date.

Case Description

We report a 59-year-old woman with a benign epidermoid cyst in the cerebellopontine angle that showed malignant transformation after 6 years. Magnetic resonance imaging (MRI) at the time of initial onset displayed a high-intensity signal on diffusion-weighted imaging (DWI), no peritumoral edema, and no enhancement on contrast-enhanced T1-weighted imaging. On the other hand, MRI at the time of malignant transformation showed a low-intensity signal on DWI, peritumoral edema, and enhancement of the tumor capsule on contrast-enhanced T1-weighted imaging. Pathological findings at the time of the first surgery differed from normal benign epidermoid cysts, in that stratified squamous epithelial metaplasia was observed, and immunohistochemical (IHC) analysis showed positive p53 staining. In addition, IHC analysis at the time of malignant transformation demonstrated positive p16 staining.

Conclusion

In benign epidermoid cysts, it is considered to cause malignant transformation when squamous metaplasia or p53 mutation is observed. Therefore, strict follow-up is required while paying attention to the characteristic changes in MRI for early detection and timely treatment of malignant transformation.

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.

Sudden Death Due to a Cerebellopontine Angle Epidermoid Cyst: Case Report

Epidermoid cyst of the brain is a rare benign embryonal tumor. It has an excellent prognosis because of its slow-growing nature. Clinically, symptoms are variable and depend on the location of the cyst. Sudden death may occur as a result of lethal complications because of the tumor growth, but it is still rare. In this article, we present a rare case of sudden unexpected death of a 58-year-old man, with no neurologic history, due to an epidermoid cyst of the brain diagnosed at autopsy.

Extent of resection of epidermoid tumors and risk of recurrence: case report and meta-analysis

OBJECTIVE

Intracranial epidermoid tumors are slow-growing, histologically benign tumors of epithelial cellular origin that can be symptomatic because of their size and mass effect. Neurosurgical resection, while the treatment of choice, can be quite challenging due to locations where these lesions commonly occur and their association with critical neurovascular structures. As such, subtotal resection (STR) rather than gross-total resection (GTR) can often be performed, rendering residual and recurrent tumor potentially problematic. The authors present a case of a 28-year-old man who underwent STR followed by aggressive repeat resection for regrowth, and they report the results of the largest meta-analysis to date of epidermoid tumors to compare recurrence rates for STR and GTR.

METHODS

The authors conducted a systemic review of PubMed, Web of Science, and the Cochrane Collaboration following the PRISMA guidelines. They then conducted a proportional meta-analysis to compare the pooled recurrence rates between STR and GTR in the included studies. The authors developed fixed- and mixed-effect models to estimate the pooled proportions of recurrence among patients undergoing STR or GTR. They also investigated the relationship between recurrence rate and follow-up time in the previous studies using linear regression and natural cubic spline models.

RESULTS

Overall, 27 studies with 691 patients met the inclusion criteria; of these, 293 (42%) underwent STR and 398 (58%) received GTR. The average recurrence rate for all procedures was 11%. The proportional meta-analysis showed that the pooled recurrence rate after STR (21%) was 7 times greater than the rate after GTR (3%). The average recurrence rate for studies with longer follow-up durations (≥ 4.4 years) (17.4%) was significantly higher than the average recurrence rate for studies with shorter follow-up durations (< 4.4 years) (5.7%). The cutoff point of 4.4 years was selected based on the significant relationship between the recurrence rate of both STR and GTR and follow-up durations in the included studies (p = 0.008).

CONCLUSIONS

STR is associated with a significantly higher rate of epidermoid tumor recurrence compared to GTR. Attempts at GTR should be made during the initial surgery with efforts to optimize success. Surgical expertise, as well as the use of adjuncts, such as intraoperative MRI and neuromonitoring, may increase the likelihood of completing a safe GTR and decreasing the long-term risk of recurrence. The most common surgical complications were transient cranial nerve palsies, occurring equally in STR and GTR cases when reported. In all postoperative epidermoid tumor cases, but particularly following STR, close follow-up with serial MRI, even years after surgery, is recommended.

Epidermoid cyst in temple area with skull perforation

Epidermoid cysts are benign tumors that account for approximately 1% of intracranial tumors. In very rare cases, temporally located extradural intradiploic epidermoid cysts can cause neurological symptoms and skull perforation. Herein, we report the case of a 34-year-old woman who underwent successful treatment of an epidermoid cyst in the temporal region accompanied by neurological symptoms. Accurate radiological evaluation and complete removal of the tumor and capsule play a vital role in ensuring favorable long-term outcomes. Computed tomography and magnetic resonance imaging scans can provide an accurate assessment of the extent of intracranial expansion and invasion of the cerebral parenchyma, as well as enabling the precise localization and characterization of the bone defect and mass. In addition, collaborative surgery with a neurosurgeon is required for cases involving intracranial expansion and dural invasion.

Endoscopic Removal of an Epithelial Cyst of the Zygoma

This study elaborates a brief overview of epithelial cysts in the bones of the skull and describes an unusual patient with an epidermoid cyst of the zygoma. This report focuses on an endoscopic preauricular infratemporal fossa approach for resection of a left epidermoid cyst of the zygoma. Preoperative magnetic resonance imaging and computed tomography imaging as well as intraoperative endoscopic images and movie were demonstrated. The epithelial cyst was successfully removed from the patient using a minimally invasive approach utilizing endoscopes. No complications were encountered. The possible causes of this rare presentation and minimal surgical removal utilizing endoscopes were discussed in this study. According to the authors, this is the first reported study of endoscopic removal of an epidermoid cyst from the zygomatic root. The patient's previous surgical history of a tympanoplasty could have contributed to the unusual location of the lesion.

Suprasellar keratinous cyst: A case report and review on its radiological features and treatment outcome

BACKGROUND

Keratinous or epidermoid cysts (ECs) are encapsulated lesions lined by squamous cell epithelium. They comprise approximately 1% of intracranial lesions. Contrary to dermoid cysts, they lack dermal elements such as sebaceous or apocrine glands and hair follicles. The sellar region is the second most common intracranial site following the cerebellopontine angle. Here, we report a case of EC in a patient who complained of endocrine disturbances. We also performed a systematic review on previously published cases to analyze clinical and radiological characteristics and report the treatment outcomes of suprasellar ECs.

CASE DESCRIPTION

A 42-year-old woman presented with a one-year history of amenorrhea, weight gain, severe headache, and visual disturbances for 6 months. Work-up identified an elevated prolactin level and a temporal field defect of the right eye. Magnetic resonance imaging (MRI) showed a cystic suprasellar lesion pushing on the optic chiasm. She underwent endoscopic trans-sphenoidal surgery, which confirmed a keratinous cyst on histology. Postoperatively, complete resection was confirmed on imaging. She did well although her hospital stay was prolonged due to diabetes insipidus and hypocortisolism.

CONCLUSION

Chronic endocrine disturbances can be the presenting complaints of a suprasellar EC, whose T1-weighted MRI appearance can be non-specific, mimicking other differential diagnoses, such as a Rathke's cleft cyst. However, the T2-weighted MRI appearances of ECs are generally hyper-intense and lesions show diffusion restriction. Treatment is surgical and yields good outcomes in most cases reported.

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.

Intracranial squamous cell carcinoma arising in a cerebellopontine angle epidermoid cyst: A case report and literature review

RATIONALE

Most of the intracranial epidermoid cysts are benign, but malignant lesions are occasionally reported. These lesions appear as squamous cell carcinoma and carry a dismal prognosis. Here, we report a case of a primary intracranial squamous cell carcinoma arising in a cerebellopontine epidermoid cyst. The relevant literatures were also reviewed.

PATIENT CONCERNS

A 53-year-old woman presented with dizziness and diplopia 9 months in duration. Magnetic resonance imaging revealed an epidermoid cyst in the left cerebellopontine angle and prepontine region with a focal enhancing lesion on T1-weighted gadolinium-enhanced images.

DIAGNOSES

Histopathologic diagnosis revealed squamous cell carcinoma on a background of epidermoid cyst. Imaging studies excluded metastases.

INTERVENTIONS

The tumor was removed subtotally through a lateral suboccipital approach. The patient received intensity modulated radiation therapy (6720 cGy total) postoperatively.

OUTCOMES

The patient was free from recurrence of the tumor until 3 years after surgery, at which point she was lost to follow-up. The patient died 4 years after the surgery.

LESSONS

The epidermoid cyst may occasionally become malignant. Finding an area of enhancement through preoperative magnetic resonance imaging can help to make a correct diagnosis. Based on the review of previous reports, surgical removal followed by radiotherapy shows the best result to treat malignant epidermoid cysts.

Surgical Resection of Cerebellopontine Epidermoid Cysts: Limitations and Outcome

Objective  Epidermoid cysts are benign slowly growing tumors commonly involving the cerebellopontine angle (CPA). The aim of this study was to analyze the surgical limitations, surgical strategies, complications, and outcome of resection of these lesions. Material and Methods  The clinical data and outcome of 32 cases operated for CPA epidermoid between 2007 and 2015 were retrospectively analyzed. The mean follow-up period was 42.6 months, and all patients were followed up at least for a whole year. Results  There were 15 males and 17 females. The median age was 37.6 years. Headache and cranial nerves dysfunction were the most common presenting symptoms. Surgery was performed in all patients using the standard lateral suboccipital retrosigmoid approach. In three cases, microvascular decompression of an arterial loop was performed in addition to tumor excision. Total resection was accomplished in 19 out of 32 cases (59.4%), subtotal resection in 7 cases (21.9%), and only partial excision was achieved in 6 cases (18.7%). There was no recurrence or regrowth of residual tumor during the follow-up period. We had a single postoperative mortality due to postoperative pneumonia and septic shock. New cranial nerves deficits occurred in 15.6% of cases but were transient in most of them. Conclusion  The favorable outcome of total resection of CPA epidermoids should always be weighed against the critical risks that accompany it especially in the presence of tight adhesions to vital neurovascular structures. The retrosigmoid approach is suitable for the resection of these tumors even if they were large in size.

Predictors of Outcomes in Fourth Ventricular Epidermoid Cysts: A Case Report and a Review of Literature

OBJECTIVE

To present an illustrative case of fourth ventricular epidermoid cyst and review the literature to identify predictors of surgical outcomes.

METHODS

A case of fourth ventricular epidermoid cyst is presented and a systematic review of 5 popular databases was performed by independent authors. Stepwise logistic regression was performed to identify clinical predictors of outcomes.

RESULTS

A 21-year-old woman presented with 3 months of headaches and visual obscurations and was diagnosed with a multilobulated mass in the fourth ventricle. The patient underwent suboccipital craniotomy. Complete removal of the mass was achieved and the final diagnosis was consistent with an epidermoid cyst. The systematic review identified 23 studies that reported 37 patients. Mean age was 42.8 years. Mean length of time between symptom onset and diagnosis was 4.43 years. Age (P = 0.049) and duration of symptoms (P < 0.001) were significantly different between patients who experienced symptom improvement and those who did not. Duration of symptom onset to diagnosis was a significant predictor of poor outcomes (odds ratio, 1.19, 95% confidence interval, 1.003-4.785).

CONCLUSIONS

Our review found that in patients with fourth ventricular epidermoid cysts, unfavorable outcomes were predicted by older age and by longer intervals from symptom onset to diagnosis. Clinicians should maintain a high index of suspicion for fourth ventricular epidermoid cysts in patients presenting with cerebellar signs and visual disturbances.

Unusual Intraparenchymal Pontomedullary Epidermoid Cyst in a 2-Year-Old Child: A Case Report and Review of the Literature

BACKGROUND

Intrinsic brainstem epidermoid cysts are rare, benign, slow-growing lesions. Their eloquence precludes complete excision; however, subtotal resection often will result in prolonged or sometimes permanent relief of presenting symptoms and signs. We describe an unusual case and review the literature of this pathology in the pediatric population.

CASE DESCRIPTION

We report an intra-axial pontine epidermoid cyst in a 2-year-old girl who presented with developmental delay, multiple cranial nerve palsies, and pneumonia. Magnetic resonance imaging demonstrated an intrinsic pontine lesion with partial restricted diffusion and an enhancing plaque, the latter not typically seen in congenital lesions like epidermoid. However, gross surgical inspection and histopathology confirmed an epidermoid.

CONCLUSIONS

Our case, supported by the literature, shows that brain stem epidermoid cysts may have atypical radiologic characteristics and that near-total resection remains safe and can improve outcome.

Brainstem epidermoid cyst: An update

The incidence of epidermoid tumors is between 1% and 2% of all intracranial tumors. The usual locations of epidermoid tumor are the parasellar region and cerebellopontine angle, and it is less commonly located in sylvian fissure, suprasellar region, cerebral and cerebellar hemispheres, and lateral and fourth ventricles. Epidermoid cysts located in the posterior fossa usually arise in the lateral subarachnoid cisterns, and those located in the brain stem are rare. These epidermoids contain cheesy and flaky white soft putty like contents. Epidermoid cysts are very slow growing tumors having a similar growth pattern of the epidermal cells of the skin and develop from remnants of epidermal elements during closure of the neural groove and disjunction of the surface ectoderm with neural ectoderm between the third and fifth weeks of embryonic life. We are presenting an interesting case of intrinsic brainstem epidermoid cyst containing milky white liquefied material with flakes in a 5-year-old girl. Diffusion-weighted imaging is definitive for the diagnosis. Ideal treatment of choice is removal of cystic components with complete resection of capsule. Although radical resection will prevent recurrence, in view of very thin firmly adherent capsule to brainstem, it is not always possible to do complete resection of capsule without any neurological deficits.

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.

Malignant transformation of an intramedullary epidermoid cyst in the thoracic region of the spinal cord

Malignant transformation of epidermoid cysts (ECs) to squamous cell carcinomas (SCCs) in the CNS is exceedingly rare and has only been described in intracranial ECs. In this article, the authors describe a 53-year-old man with a history of a previously resected T3–4 EC, who presented with a 2-month history of progressively worsening weakness in the left side of his body. Magnetic resonance imaging revealed an enhancing mass in the T3–4 region, the exact location of the previous cyst. The mass was resected in gross-total fashion, and pathological analysis revealed an SCC. Postoperatively, the patient regained full strength in his lower extremities. After the resection, he received radiotherapy administered at an isodose of 50 Gy. To the authors' knowledge, this is the first reported case of malignant transformation of an intramedullary spinal EC in the literature.

An analysis of intracranial epidermoid tumors with malignant transformation: treatment and outcomes

OBJECTIVE

While typically benign, epidermoid tumors upon rare occasion can undergo malignant transformation, which carries a poor prognosis. Here, we reviewed treatment strategies and analyzed outcomes for every case of malignant epidermoid tumor reported since its original description in 1912.

METHODS

A comprehensive literature review identified all reported cases of malignant transformation of intracranial epidermoid tumor. Treatments were categorized as follows: palliative management, stereotactic radiosurgery (SRS), chemotherapy, and surgery plus multiple (2+) adjuvant therapies. Survival data of these groups were compared to treatment outcomes for patients receiving only surgical resection, as reported in our previous study.

RESULTS

We identified 58 cases of intracranial epidermoid tumor with malignant degeneration. Average survival regardless of therapy was 11.8 months. Mean survival outcomes for groups treated with palliative management, chemotherapy, SRS, and multiple postoperative adjuvant therapies were 5.3 months, 25.7 months, 29.2 months, and 36.3 months, respectively. Outcomes for the groups including SRS, chemotherapy, and multiple post-operative adjuvant therapies were statistically significant compared to surgical resection alone.

CONCLUSION

While there remains a lack of consensus regarding the best approach to the management of patients with malignant epidermoid tumors, our systematic analysis characterizes and confirms the added benefit of SRS, chemotherapy, and multimodal adjuvant therapies.

Survival outcomes for radiotherapy treatment of epidermoid tumors with malignant transformation

Epidermoid tumors are intracranial lesions that may occasionally undergo malignant transformation. Although surgical resection is the first-line treatment for malignant epidermoids, postoperative radiotherapy has been intermittently reported with favorable findings. Our analysis identified all previously reported patients with malignant epidermoids treated with surgical resection alone or surgery plus radiotherapy to examine the potential role for this adjuvant therapy. Whereas patients treated with surgery only had an overall survival of 6.6 months, those treated with postoperative radiotherapy demonstrated a statistically significant increase in survival to 12.7 months (log-rank test, p<0.003). Furthermore, the mean dosage of radiation given to this patient population was 52.2 Gy, with no appreciable survival benefit for the utilization of levels of radiation greater than 50 Gy. When determining the management for malignant transformation of epidermoid tumors, the combination of surgical resection and radiotherapy may be associated with improved short-term survival.

Posttraumatic giant extradural intradiploic epidermoid cysts of posterior cranial fossa : case report and review of the literature

We reported a unique case of posttraumatic giant infratentorial extradural intradiploic epidermoid cyst. A 54-year-old male, with a previous history of an open scalp injury and underlying linear skull fracture in the left occipital region in childhood, presented with a painful subcutaneous swelling, which had been developed gradually in the same region and moderate headache, nausea, vomiting and cerebellar ataxia. The duration of symptoms on admission was 3 months. Imaging studies revealed occipital bone destruction and giant extradural intradiploic lesion. The preoperative diagnosis was giant infratentorial extradural intradiploic epidermoid cyst. Surgery achieved total removal of the lesion, which was histologically confirmed and the postoperative course was uneventful. To our knowledge, this is the first case of giant infratentorial extradural intradiploic epidermoid cyst with a traumatic etiology described in the literature.

Intradiploic epidermoid causing spontaneous extradural hematoma: case report

OBJECTIVE

A case of an intradiploic epidermoid tumor leading to spontaneous extradural hematoma is reported. Intradiploic epidermoids are not common intracranial tumors. This is the first reported case of intradiploic epidermoid presenting as a spontaneous extradural hematoma.

CLINICAL PRESENTATION

The patient presented with sudden onset of headache and deterioration in the sensorium. A computed tomographic scan revealed a lesion causing erosion of both tables of the calvarium and a mixed intensity extradural hematoma.

INTERVENTION

The patient underwent immediate operation, and evacuation of the hematoma and excision of the tumor were performed.

CONCLUSION

Intradiploic epidermoid tumors so rarely present with extradural hemorrhage that prophylactic removal cannot be recommended in all such cases. However, in view of the seriousness of the hemorrhage, prophylactic removal may be recommended, especially if the patient, such as a sportsman, child, or elderly person, is prone to injuries.

Malignant transformation of posterior fossa epidermoid cyst

The authors report the case of a 45-year-old man who presented with a short duration of a painful ophthalmoparesis. Initial magnetic resonance imaging revealed an extraaxial petroclival mass characteristic of an epidermoid cyst, with the exception of a contiguous contrast-enhancing lobule. A subtotal resection was performed with the histopathological diagnosis revealing malignant transformation of an epidermoid cyst. Despite aggressive postoperative adjuvant therapy, the patient developed leptomeningeal metastasis and died shortly thereafter. The presence of contrast enhancement at the site of an epidermoid cyst combined with an acute, progressive neurological deficit should alert the treating physician to the possibility of a malignant transformation. When transformation does occur, the clinical and radiological course is quite aggressive as compared with the indolent growth of epidermoid cysts. Treatment options include surgery with adjuvant chemotherapy or radiotherapy. We review the pertinent features of this case along with the relevant literature regarding primary intracranial squamous cell carcinomas.

Unusual magnetic resonance characteristics of a cerebellopontine angle epidermoid cyst with upper cervical spinal canal extension

We present a 27-year-old woman with an epidermoid cyst at the cerebellopontine (CP) angle with caudal extension into the upper cervical spinal canal. The lesion showed unusual hyperintensity on T1-weighted images, and hypointensity on T2-weighted images. We used microneurosurgical techniques for tumour dissection and excision. To our knowledge, this is the fifth example in Index Medicus/MEDLINE of histopathologically proven CP angle epidermoid with cervical spine extension.

Intrinsic brainstem epidermoid cyst. Case report and review of the literature

Brainstem epidermoid cysts are rare lesions, with only 18 reported cases in the literature and only five purely intrinsic epidermoid cysts within this group. The authors present the case of a 3-year-old girl with a history of chronic headaches, progressive diplopia, and relapsing and remitting mild right hemiparesis who was found to harbor an intrinsic brainstem epidermoid cyst at the pontomedullary junction. Initial working diagnoses included intrinsic brainstem astrocytoma and cavernoma. After tumor enlargement and progressive symptoms, a diffusion-weighted (DW) magnetic resonance (MR) imaging sequence was performed and a definitive diagnosis of an intrinsic brainstem epidermoid cyst was made in the patient. The patient underwent a suboccipital craniotomy and complete resection of the cyst with the aid of intraoperative neurophysiological monitoring. Three years after the operation, the patient is neurologically intact and no evidence of tumor recurrence has been found. The rarity of brainstem epidermoid cysts can make their diagnosis difficult; thus a DW MR imaging sequence of the brain is a useful diagnostic modality. Intrinsic brainstem epidermoid cysts can be removed safely, in a manner similar to that used for the surgical treatment of focal tumors.

Malignant transformation eight years after removal of a benign epidermoid cyst: a case report

Malignant transformation of benign epidermoid cysts is rare and their prognosis remains poor. A 56-year-old woman presented with left facial hypoesthesia and photophobia in the left eye. She had undergone removal of a benign epidermoid cyst in the cerebellopontine angle 8 years previously. Magnetic resonance imaging of the brain revealed a cystic lesion in the left cerebellopontine angle. The cyst wall was enhanced by gadolinium-DTPA. She underwent removal again and the histopathologic diagnosis was squamous cell carcinoma. Gamma knife radiosurgery was performed on the remnant lesion with a marginal dose of 15 Gy. The tumor shrank rapidly for 2 months after radiosurgery, but recurred 9 months later. She underwent radiosurgery again with a marginal dose of 12 Gy. A gradual increase in the size of the enhanced lesion was seen during the 4-month follow-up period subsequent to the second radiosurgery. Careful observation, employing serial magnetic resonance images, is necessary for incompletely resected epidermoid cysts because intervals before malignant transformation reportedly range from 3 months to 33 years. Newly identified contrast enhancement strongly indicates malignant change in epidermoid cysts. Gamma knife radiosurgery may be useful for short-term control of intracranial squamous cell carcinomas, but long-term effects are presently unknown.

Malignant transformation of intra-cranial epithelial cysts: systematic article review

INTRODUCTION

Epidermoid and dermoid cysts are among the most benign intra cranial tumors. Their malignant transformation into squamous cell carcinoma is rare. The authors reviewed the literature.

MATERIALS AND METHODS

MEDLINE and SCIENCE DIRECT searches, and examination of the references in the selected articles yielded 74 patients, 52 of whom fulfilled Garcia's criteria and were selected for the study. Survival analyses were performed to determine whether survival differences were of statistical significance, and P < 0.05 was considered as significant.

RESULTS

Malignant transformation is characterized by a rapid onset of symptoms, recurrence, leptomeningeal carcinomatosis (LC), and tumor enhancement at Computed Tomography Scan or Magnetic Resonance Imaging (87.8 showed this radiological feature). In this review, the SCCs were classified in five groups: (1) Initial malignant transformation of a benign cyst; (2) malignant transformation from a remnant cyst; (3) malignant transformation of a dermoid and epithelial cyst; (4) malignant transformation with leptomeningeal carcinomatosis; (5) other malignancies arising from benign cysts. The median survival was 9 months. Statistics show that LC was of poor prognosis and radiotherapy, although not statistically significant, seems effective against such lesions, with a median survival of 26 months as opposed to 3 months (P=0.077).

CONCLUSION

Although rare, malignant transformation of intracranial epithelial cysts has a poor prognosis and surgery followed by radiotherapy seems to be the best therapeutic modality.

Intradiploic epidermoid cysts of the skull: a report of four cases

Epidermoid cysts are uncommon, benign and slow-growing lesions. They may often reach an enormous size without producing neurological symptoms. Intradiploic epidermoid cysts are nearly 25% of all epidermoids. They are derived from ectodermal remnants that stay within the cranial bones during embryonic development. Intradiploic epidermoid cysts can be located in any part of the skull. Two of our four cases were located in left occipital bone and the others were in the frontal bone. These tumours can occur at any age from the first to the seventh decade of life. Our cases had a mean age of 38.75 years (19-55 years). They may reach great sizes before the initial diagnosis and may produce major neurological signs. For good long-term prognosis, correct radiological assessment and complete removal of the tumour with its capsule are essential. We report four cases of intradiploic epidermoid cysts of the skull and analyse the clinical, radiological features and treatment of these lesions in the light of relevant literature.

Endoscope-assisted microsurgical resection of epidermoid tumors of the cerebellopontine angle

Object. Epidermoid tumors located in the cerebellopontine angle (CPA) are challenging lesions because they grow along the subarachnoid spaces around delicate neurovascular structures and often extend into the middle cranial fossa. The purpose of this study was to determine the value of endoscopic assistance in the microsurgical resection of these lesions, in which total removal is the therapy of choice.

Methods. Eight patients harboring an epidermoid tumor of the CPA were treated using an endoscope-assisted microsurgical technique. A retrosigmoid suboccipital approach was used in five patients and a pterional transsylvian approach was chosen in the other three. In four patients the lesion was resected microsurgically and the endoscope was used repeatedly to verify complete tumor removal, whereas most of the tumor mass was removed with the aid of an operating microscope in the other four. Tumor parts extending into other cranial compartments that were not visible through the microscope were removed under endoscopic view by using rigid rod-lens scopes with 30 and 70° angles of view.

All epidermoids were completely evacuated and the membranes were widely resected. Large tumors occupying both the middle and posterior cranial fossa were removed through a single small opening without enlarging the craniotomy. Permanent hearing loss and permanent hypacusis were observed in one patient each. One patient with facial and one with abducent nerve palsy recovered within 6 and 4 months, respectively. A transient weakness of the chewing muscles was encountered in one patient. Postoperative magnetic resonance imaging revealed no residual tumor in any patient. To date no recurrences have been observed (follow up range 12–98 months).

Conclusions. The endoscope-assisted microsurgical technique enables safe removal even when tumor parts are not visible in a straight line. Tumor extensions into adjacent cranial compartments can be removed with the same approach without retracting neurovascular structures or enlarging the craniotomy.

Swelling on the head—a forgotten lesson: a case report of an intradiploic epidermal cyst with an iatrogenic complication

Swellings on the head are common, but all require appropriate investigation and caution must be exercised during surgical intervention. We report a patient in whom an attempt at biopsy of a swelling in the scalp was made without any radiological imaging and led to an intracranial complication that caused a neurological deficit. The lesion was an intradiploic epidermal cyst. Though appropriate precautions are usually taken, lessons previously learnt are sometimes forgotten. We would therefore like to remind readers that swellings of the scalp that seem to be attached to the skull on clinical examination should be investigated by radiographs and preferably by computed tomography before surgical intervention because of the possibility of intracranial extension.

Congenital Dermoid Cyst of the Anterior Fontanelle in Turkish Children-Four Case Reports-

Four cases of congenital inclusion dermoid cysts located over the anterior fontanelle occurred in male Turkish children aged 6 months to 5 years. These rare cysts presented as slow-growing soft masses over the anterior fontanelle. The cysts were totally removed without recurrence. Dermoid cysts can be easily cured because of the absence of intracranial extension.

Reversible bilateral vestibular impairment caused by fourth ventricle epidermoid tumor

A 26-year-old man presented with an epidermoid tumor of the fourth ventricle manifesting as headache with nausea and vertigo. Neurological examination revealed no cerebellar signs, except nystagmus. Bilateral vestibular impairment was identified by the caloric test. The tumor was removed via the midline suboccipital approach. The bilateral peripheral vestibular function recovered remarkably postoperatively. This marked improvement suggests that the bilateral vestibular impairment was caused by compression of the vestibular nuclei by the tumor.

Malignant squamous degeneration of a cerebellopontine angle epidermoid tumor. Case report

The authors present the case of a woman with a cerebellopontine angle (CPA) epidermoid cyst that degenerated into a squamous cell carcinoma. Malignant degeneration of an epidermoid cyst is an extremely rare occurrence. Malignant transformation must be considered in the differential diagnosis when new contrast enhancement on imaging studies and progressive neurological deficit are seen in a patient harboring an epidermoid cyst. The patient initially presented with a 10-year history of left trigeminal neuralgia, subacute left-sided hearing loss, and with facial weakness of 3 weeks' duration. Initial magnetic resonance (MR) imaging revealed a left CPA mass, consistent with an epidermoid. There was faint contrast enhancement where the tumor was in contact with the lateral brainstem. A subtotal resection was performed. Histopathological findings were consistent with an epidermoid tumor. One year after initial presentation, the patient's neurological deficit had increased, and follow-up MR imaging demonstrated a large contrast-enhancing tumor filling the left CPA and compressing the brainstem. At repeated surgery a squamous cell carcinoma arising from the previous epidermoid was found. The patient was subsequently treated with external-beam radiotherapy and stereotactic radiosurgery. Her tumor stabilized. Three years and 8 months after the patient's initial presentation, a new area of tumor developed at the torcular Herophili. The patient died shortly thereafter. Malignant squamous degeneration is a rare cause of enhancement on MR images, as is progressive neurological deficit in a patient with an epidermoid. The combination of subtotal resection, external-beam radiotherapy, and stereotactic radiosurgery may be useful for local tumor control but the long-term prognosis is guarded.

Congenital inclusion cysts of the anterior fontanelle

BACKGROUND

Congenital inclusion cysts of the anterior fontanelle are rare lesions. Both dermoid and epidermoid cysts are located in the midline of the scalp and occupy the subgaleal space.

METHODS

We report 7 cases, 4 boys (57.1%), and 3 girls (42.9%), with ages ranging from 3 months to 16 years (mean 40.85 +/- 68.56 months; median 10 months). Four patients (57.1%) were white and 3 (42.9%) were Afro-Brazilian.

RESULTS

The cysts had manifested soon after birth in all patients. They gradually enlarged, with no intracranial extensions. Four patients had dermoid cysts and the others had epidermoid cysts. All of them underwent surgery with complete excision of the cyst and no capsular rupture. There were no complications and no deaths.

CONCLUSIONS

Congenital inclusion cysts of the anterior fontanelle are rare lesions that usually manifest at birth. The diagnosis is usually easy and surgery is mandatory, with a good prognosis. Recurrence is rare.

Intra-axial dermoid/epidermoid tumors of the brainstem in children

BACKGROUND

Epidermoid and dermoid cysts are rare intracranial space-occupying lesions, which account for about 1% of all intracranial tumors; they are even rarer in the pediatric age group. Among the various locations, that inside the brain stem is quite exceptional (only 12 cases reported to date in the literature). We report two additional cases occurring in children, underlining their clinical characteristics, the difficulties faced in the diagnostic work-up, and the surgical treatment adopted (which consisted of removal of the cyst contents and partial resection of the cyst membrane, because of its adherence to the surrounding nervous and vascular structures).

METHODS

We report two cases of intraaxial dermoid/epidermoid cysts observed within the last 5 years. Both patients complained of cervico-nuchal pain, with a remittent/intermittent character in one of them; this patient also exhibited transient 6th and 7th cranial nerve deficit. One lesion was approached through the floor of the fourth ventricle, the second one through the ventrolateral aspect of the brainstem.

RESULTS

Subtotal tumor resection was achieved in both cases. Both patients had a smooth postoperative course without permanent neurological deficits. In the first patient residual tumor remains stable on follow-up MRI. In the second one, early tumor regrowth necessitated a second operation, after which the residual tumor has remained stable.

CONCLUSIONS

Based on our experience we suggest that a cautious surgical approach ("conservative" resection) to these lesions is the best choice. In fact, attempts at radical removal carry unacceptably high morbidity and mortality rates.

Assessment and surgical management of posterior fossa epidermoid tumors: report of 28 cases

OBJECTIVE

The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series.

METHODS

We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated.

RESULTS

Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed.

CONCLUSION

By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.

Epidermoid tumor of the interhemispheric fissure

In this report, we present a case of an interhemispheric epidermoid presenting with generalized seizure. The tumor was demonstrated radiologically and discussed with the pertinent literature.

Cranial cystic epidermoid: report of two cases and review of the literature

Intercranial epidermoid tumours are benign lesions of congenital origin that are potentially curable. Although computerized axial tomography (CT) and magnetic resonance imaging (MRI) are usually diagnostic, a few atypical features sometimes make pre-operative diagnosis difficult. Two cases of cystic epidermoids with peripheral ring enhancement are reported. Relevant literature has been reviewed.

The long history of a cerebello-pontine angle epidermoid tumour--a case report and lessons learned

The authors present the case of a patient accurately diagnosed and operated on for an epidermoid cyst in the CPA region, 30 years after the clinical onset with the initial symptom of hypoacusis. At the time of the operation, the patient presented with advanced CPA syndrome, and the tumour had grown to an enormous size. Complete capsule removal was not attempted due to its tenacious adherence to vital neurovascular structures. Thirteen years after surgery, the patient underwent a second operation due to tumour regrowth. The case provides supporting evidence that the clinical findings of a CPA epidermoid cyst may be minimal, and remain so for extended periods of time until the tumour has spread widely. Epidermoids tend to insinuate in the cisterns around cranial nerves, blood vessels, and the brainstem, rather than compressing these structures. The importance of early detection and radical removal, presently facilitated by Magnetic Resonance Imaging, is emphasized.

Traumatic brain injury associated with an intradiploic epidermoid cyst: case report

We present a case of an intradiploic epidermoid cyst with an unusual complication. After a minor fall, a patient with a large right parietal epidermoid suffered a traumatic brain injury caused by the transfer of the force of the fall through the cyst contents to the brain and by transdural herniation of the cyst contents into brain parenchyma. Elective resection of intradiploic epidermoids associated with large bony defects is recommended to avoid this apparently rare but potentially dangerous complication of an otherwise benign condition.