T1 Hyperintense Prepontine Mass with Restricted Diffusion--A White Epidermoid or a Neuroenteric Cyst?

Bilobed Prepontine White Epidermoid Cyst Camouflaged as Tubercular Abscess: A Case Report

Epidermoid cysts are ectodermally derived benign extra-axial lesions that have typical imaging characteristics following cerebrospinal fluid (CSF) signal intensity, but occasionally show unusual hyperintensity on T1-weighted images (T1WI), known as white epidermoid, thus posing a diagnostic challenge. We report an unusual case of bilobed prepontine white epidermoid masquerading as tuberculous abscess in a known case of tubercular meningitis.

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.

Combined endoscopic endonasal transtubercular and transclival approaches for large neurenteric cyst in posterior cranial fossa: A case report and literature review

Background:

Intracranial neurenteric cysts (NCs) are extremely rare tumors that more commonly involve the posterior fossa than any other cranial part. While transcranial skull base surgery has been the mainstay of treatment, the utility of endoscopic transnasal surgery (ETS) remains to be established.

Case Description:

We report a case of a large posterior fossa NC extensively involving the suprasellar region, cerebellopontine angle, and prepontine cistern, which we successfully resected with ETS through a combination of transtubercular and transclival routes. Before surgery, the patient presented with abducens nerve and pseudobulbar palsies, which resolved within 2 weeks postoperatively. The patient remained free from recurrence for 3 years postoperatively.

Conclusion:

Extended ETS may offer a minimally invasive option for the posterior fossa NC, extensively occupying the ventral space of the brainstem.

Predictors for complete surgical resection of posterior fossa neurenteric cysts: A case report and meta-analysis

Background

Incomplete resection of neurenteric cysts (NCs) has been associated with increased recurrence rates in patients compared to complete resection (CR) and information on intracranial NCs appearance on diagnostic imaging is scarce. We sought to identify factors associated with CR and provide the largest up-to-date review of NCs appearances on various diagnostic images.

Methods

Data from Medline, EMBASE, and Web of Science were extracted. Univariate and multivariate logistic regression models were used to analyze factors associated with CR.

Results

A total of 120 publications reporting 162 original cases on posterior fossa NCs met the inclusion criteria for analysis. Eighty-nine (55.6%) of the patients were female, the mean (SD) age of the patients' during operation was 34.3 (16.9) years, and CR was achieved in 98 (60%) of patients. Univariate analysis identified male sex as a statistically significant predictor for complete reaction (OR 2.13, 95% Cl 1.10-4.11, P = 0.02). The retrosigmoid approach (OR 1.89, 95% Cl 0.98-3.63, P = 0.06), far lateral approach (OR 0.46, 95% Cl 0.21-1.02, P = 0.06), and pediatric patient (OR 2.45, 95% Cl 0.94-6.56, P = 0.07) may be possible predictors for CR, however, they were not statistically significant. NCs are mainly hypodense on CT (32 [61.5%]), varied greatly in intensity on T1WI, hyperintense on T2WI magnetic resonance imaging (98 [67.1%]), and hyperintense on fluid-attenuated inversion recovery (17 [63.0%]).

Conclusion

We recommend utilizing various diagnostic imaging tests to help reduce misdiagnoses when identifying intracranial NCs. For patient safety, CR should be achieved when possible, to reduce risk of additional operations due to recurrence.

Microsurgical Treatment of Epidermoids. Case Report and Literature Review

The aim of the research: study the features of surgical treatment of epidermoids.

Materials and methods. We present a literature review and the clinical case of surgical treatment of a patient with epidermoid. We have searched medical databases: Medline, Russian Science Citation Index, EMedicine, United Medical Knowledge Base. We considered the features of the clinic, diagnosis, and surgical intervention. The article presents a clinical example of successful surgical treatment of a patient with an epidermoid cyst of the posterior cranial fossa. The result of the literature review was the writing of a clinical lecture; the current state of the issue of etiopathogenesis, diagnosis and management of patients with epidermoids was studied.

Results. The authors found that total microsurgical removal is the method of choice, and the operative technique should be aimed at preventing postoperative aseptic meningitis. Although it was not possible to establish the cause of the development of aseptic meningitis, the authors assume that the mechanism of its formation lies in the self-breaking of the capsule of the epidermoid cyst, probability of which was confirmed by a number of studies. Further study of this pathology is a promising direction in neurosurgery.

Conclusion. Difficulties in the diagnosis and choice of surgical tactics point at the need for detailed preoperative planning of surgical intervention, performing a precise total removal of a lesion with compliance with preventive measures for aseptic meningitis to improve clinical results and reduce the incidence of perioperative complications.

Neuroendodermal cyst in the fourth ventricle of a dog

CASE REPORT

We describe the MRI appearance and surgical outcome of a rare neuroendodermal cyst in the fourth ventricle of a German Shorthaired Pointer. The dog presented with uncoordinated gait and occasional falling that increased when she became excited. The MRI appearance is shown and the surgical treatment described. Recurrence occurred on two occasions and the dog was euthanased.

CONCLUSION

Recurrence of these cysts is highly likely unless there is complete surgical resection.