White Epidermoid of the Sylvian Fissure Masquerading as a Dermoid Cyst: An Extremely Rare Occurrence

White Epidermoid Cyst: An Illustrative Case

White epidermoid cysts are a rare type of epidermoid cyst that appears hyperintense on T1 weighted magnetic resonance imaging (MRI) and are known for their characteristic pearly white outer appearance on gross pathology. White epidermoid cysts are not common findings; therefore, this illustrative case report was written to highlight the characteristics, progression, radiological evaluation, and management of a patient who presented to our center. This case report emphasizes the importance of determining the proper diagnosis to treat and manage the condition appropriately and avoid potential future complications.

Quantitative analysis of a posterior fossa teratomas with unusual CT and MR Characteristics--illustrative case

BACKGROUND

Intracranial teratomas or other cystic lesions with atypical imaging manifestations can still be frequently seen clinically. The specific reasons for unusual imaging manifestations need to be further explored.

OBSERVATIONS

A case of adult teratoma in the posterior fossa with unusual imaging manifestations was reported. The chemical composition of its cystic fluid was quantitatively detected, and in vitro imaging simulation experiments were performed on some fluid substances with similar cystic fluid properties to explore the reasons for special imaging manifestations. The content of inorganic substances and protein in the cystic fluid were both low, with no melanin detected. In vitro experiments revealed that MR T1 signals could increase with protein content rising and changes in MR T2 signals presented no obvious correlation with it. CT values increased gradually with protein concentration rising. The substances with similar viscosity had similar CT values, whereas substance viscosity showed no significant correlation with changes in MR signals.

CONCLUSION

The abnormality of imaging manifestations cannot be confirmed as the result of "high protein content", nor can it be simply attributed to bleeding. Further research is required for the impact of the combination of paramagnetic particles and biofluid on imaging.

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.

Surgical Nuances of Intramedullary White Epidermoid Cyst in the Conus Medullaris: A Rare Entity

Spinal epidermoid cysts (ECs) are benign slow-growing spinal tumors. The account for <1% of spinal tumors and are usually found intradural extramedullary. This report is regarding two rare cases of intramedullary white ECs present at the conus medullaris. In the first case, a 32-year-old male presented with a complaint of lower backache for 5 years, which progressively increased in intensity, radiating to the left leg. The patient had left lower limb weakness in the form of difficulty in walking. On examination, power of left knee and ankle was 4/5. Left extensor hallucis longus power was 3/5. Left Babinski sign was extensor. In the second case, a 42-year-old male, presented with a complaint of numbness over the left foot for 5–6 months. On examination, the power of the left ankle was 3/5, left extensor hallucis longus was 3/5. Both patients had EC in conus medullaris, which was hyperintense on T1-weighted magnetic resonance imaging and underwent laminectomy with the evacuation of the cyst with electrocoagulation of cyst epithelial lining. White ECs are extremely rare in the conus medullaris. Electrocoagulation of the cyst wall is like walking on a tight rope. Liberal electrocoagulation can lead to the neurological deficit but decreases the chances of recurrence. On the other hand, conservative electrocoagulation can lead to recurrence but decreases the chance of a new deficit. Recurrence should also lead to suspicion of atypical changes in the cyst wall, which may require adjuvant treatment such as radiotherapy and chemotherapy.

The Dilemma of Multifocality in Insular Tumors: Multicentricity versus Metastasis

Background and Purpose:

Multifocality and metastasis from insular glioma are extremely rare. Pathological insights and elaboration of the clinical course of this condition will contribute to their better understanding.

Materials and Methods:

Among 123 consecutively operated insular gliomas, 5 patients (4.2%) presented with a multifocal tumor. The clinico-radiological, histo-molecular, and treatment outcomes were noted and compared with the unifocal insular glioma cohort.

Results:

Among the five patients, all were males and involved the right insular lobe. Three patients presented with synchronous tumors, while two patients developed metachronous multifocal tumors. The histology of the insular tumor was Grade I glioma in 1, Grade II astrocytoma with p53 mutation in 2, and anaplastic astrocytoma and glioblastoma in one patient each. Histological confirmation of the second lesion was performed in two patients, showing the same histology of the insular tumor. Interconnection between the tumors was apparent through cerebrospinal fluid pathways in four patients, while no such connection could be established in one patient. Barring the patient of Grade I glioma, the rest of the patients died within months of the diagnosis.

Conclusion:

Multifocal insular glioma is rare and probably represents a biologically more aggressive tumor. Insular glioma that touches the ventricle appears a common denominator for multifocality. True multicentricity is rare. The prognosis in insular glioma with multifocality is poor in non-Grade I gliomas.

A Single-Center Surgical Experience of Interhemispheric Epidermoids and Proposal of a New Radiological Classification

BACKGROUND

Epidermoids account for <1.5% of all intracranial tumors. Overall, the cerebellopontine angle has been the most commonly reported location. In the supratentorial compartment, epidermoids will usually be found in the suprasellar area, sylvian fissure, and intraventricular area. The interhemispheric fissure represents an extremely rare location for supratentorial epidermoids, with limited cases reported previously. Surgery of an interhemispheric epidermoid can be challenging because of its adherence to the anterior cerebral artery branches or the brain parenchyma itself. In the present study, we have reported the largest Series of interhemispheric epidermoid tumors to better understand the clinical behavior, radiological features, and surgical outcomes.

METHODS

In the present study, we retrospectively evaluated the data from 22 consecutive patients with interhemispheric epidermoids treated surgically during the past 10 years (2009-2019) at our center. During the same study period, we had treated 2355 patients with brain tumors (both primary and secondary), including 262 patients with intracranial epidermoids. Therefore, interhemispheric epidermoids comprised 0.009% of all brain tumors and 8.4% of all intracranial epidermoids in our experience. These patients all had newly diagnosed tumors and had undergone surgery for the first time at our center. All surgical specimens had been confirmed histopathologically.

RESULTS

The mean age of the patients was 31 years (range, 17-61 years), with a male predilection. Seizures and headache were the most common mode of presentation. The average tumor size was 5.2 cm (range, 3.5-10 cm). Of the 22 tumors, 21 were in the anterior two thirds of the fissure. Anatomical distortion of the corpus callosum was seen in 13 patients (59%). The extent of excision was total in 17 (77.3%), near total in 3 (13.6%), and subtotal in 2 (9%) patients. The near or subtotal excisions had been necessary because of either tumor adherence to the pericallosal artery (n = 3) or a missed tumor lobule (n = 2). The mean follow-up time was 32 months, with no tumor recurrence.

CONCLUSION

Interhemispheric epidermoids can often reach a large size with substantial lateral extension found at diagnosis. The position of the anterior cerebral Artery branches can help to differentiate interhemispheric epidermoids from radiologically similar corpus callosum, velum interpositum, and cavum septum pellucidum epidermoids. Complete surgical excision with minimal complications is feasible, with good long-term outcomes.