Atypical CT and MRI aspects of an epidermoid cyst

Parasellar epidermoid cyst with unique radiological features: A case report and review of the literature

Intracranial epidermoid cysts (ECs) are encapsulated lesions lined by squamous cell epithelium and the most location is the cerebellopontine angle and appears with cerebrospinal fluid-like irregular mass. Occasionally, ECs present as high-density masses on computed tomography and atypical features in magnetic resonance images in the unusual area, which makes the diagnosis difficult. Here, we report a case of a female subject who complained of episodic left facial convulsions for more than 3 months. Computed tomography plain scan revealed a large hyperdense parasellar mass with atypical magnetic resonance findings. In this report, we analyzed retrospectively the radiological characteristics and histopathology of the parasellar EC, thus increasing awareness about this unusual image features.

A Case of Trigeminal Neuralgia Due to Cerebellopontine Epidermoid Cyst: Discrepancy between Intraoperative and Radiological Findings of Constructive Interference in Steady State (CISS)

Trigeminal neuralgia (TN) is characterized by lightning pain paroxysms in the somatosensory distribution of the trigeminal nerve accompanied by hypersensitivity to non-nociceptive stimuli. Epidermoid cysts sometimes cause TN. To plan the surgery, constructive interference in steady state (CISS) image is useful for understanding the tumor’s location, extent, and relationship against the cranial nerves, and epidermoid cysts are shown as hypointense compared to cerebrospinal fluid (CSF). However, we herein describe a case with TN due to epidermoid cysts, whose intraoperative findings are different from the preoperative and postoperative CISS image. A 49-year-old woman has suffered from TN. CISS images revealed the prolonged trigeminal nerve and the hypointense tumor compared to the CSF at the right cerebellopontine angle. CISS image suggested that the tumor would surround the trigeminal nerve, reach into the Meckel cavity, and offend and compress the trigeminal nerve’s root entry zone (REZ). However, contrary to our expectation, the trigeminal nerve was not surrounded by the tumor. Neuroendoscope revealed that the tumor compressed the REZ, but the tumor was not present in the Meckel cavity. We performed partial tumor removal around the trigeminal nerve, and her symptoms improved. However, the postoperative CISS image was similar to the preoperative one, and so we could not evaluate the remaining tumor. The pathological diagnosis was epidermoid cysts. Intraoperative findings are sometimes different from the pre- and postoperative CISS images, making it difficult to follow up the remaining part of the epidermoid cyst.

Epidermoid cysts of the cavernous sinus: clinical features, surgical outcomes, and literature review

OBJECTIVE

Epidermoid cysts of the cavernous sinus (CS) are rare, and no large case series of these lesions has been reported. In this study, the authors retrospectively reviewed the outcomes of the surgical management of CS epidermoid cysts undertaken at their center and performed a review of any such cysts reported in the literature over the past 40 years.

METHODS

Clinical data were obtained on 31 patients with CS epidermoid cysts that had been surgically treated at the authors' hospital between 2001 and 2016. The patients' medical records, imaging data, and follow-up outcomes were retrospectively analyzed. The related literature from the past 40 years (18 articles, 20 patients) was also evaluated.

RESULTS

The most common chief complaints were facial numbness or hypesthesia (64.5%), absent corneal reflex (45.2%), and abducens or oculomotor nerve deficit (35.5%). On MRI, 51.6% of the epidermoid cysts showed low T1 signals and equal or high T2 signals. In the other lesions, the radiological findings varied considerably given differences in the composition of the cysts. Surgery was performed via the extradural approach (58.1%), intradural approach (32.3%), or a combined approach (9.7%). After the operation, symptoms remained similar or improved in 90.3% of patients and new oculomotor paralysis developed after the operation in 9.7% of patients. Seven patients (22.6%) developed meningitis postoperatively (5 aseptic and 2 septic), and all of them recovered. All patients achieved good recovery before discharge (Karnofsky Performance Status score ≥ 70). Over an average follow-up of 4.6 ± 3.0 years in 25 patients (80.6%), no recurrence or reoperation occurred, regardless of whether total or subtotal resection of the capsule had been achieved.

CONCLUSIONS

Both the extradural and intradural approaches can enable satisfactory lesion resection. A favorable prognosis and symptomatic improvement can be expected after both total and subtotal capsule resections. Total capsule resection is encouraged to minimize the possibility of recurrence provided that the resection can be safely performed.

Cholesteatoma in the Sellar Region Presenting as Hypopituitarism and Diabetes Insipidus

Clinically significant sellar cysts unrelated to pituitary adenomas are uncommon. Intracranial cholesteatomas are also rare and are most common in the middle ear and mastoid region. We report an even rarer case of cholesteatoma in the sellar region-a challenging diagnosis guided by clinical presentations, radiological signs, and biopsy, aiming at emphasize the importance of considering cholesteatoma when making differential diagnoses of sellar lesions.We present a case of cholesteatoma in the sellar region in a 56-year-old man with hypopituitarism, diabetes insipidus, and cystic imaging findings. It was difficult to make an accurate diagnosis before surgery. We present detailed analysis of the patient's disease course and review pertinent literature.The patient underwent a surgical exploration and tumor resection through a transsphenoidal approach. Pathologic results revealed a cholesteatoma. The patient's symptoms improved a lot after surgery, and the postoperative period was uneventful. Taken together, the lesion's imaging appearance, pathological characteristics, and clinical features were all unique features that lead to a diagnosis of cholesteatoma.As we did not see such reports by Pubmed and EMBASE, we believe this is the first reported case of sellar cholesteatoma presenting in this manner. This article emphasized that cholesteatomas, although rare, should be considered part of the differential diagnosis of sellar lesions.

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.

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.

Pathology of the vestibulocochlear nerve

Imaging of the vestibulocochlear nerve has evolved dramatically over the past few decades. The imaging specialist now is involved in the diagnosis of far more diagnostic entities than ever before. With this increased involvement comes the responsibility to increase collective knowledge regarding the pathophysiology of these diagnostic entities. This article is organized in a conventional way and covers congenital deformity of the internal auditory canal, neoplastic and pseudoneoplastic lesions, with special detailed emphasis on schwannoma of the eight cranial nerves (acoustic neuroma), nonneoplastic IAC/CPA pathology, including vascular loops, and numerous additional differential diagnostic entities, with particular emphasis on non-neoplastic meningeal disease. Lesions of the auditory pathway and an overview of cochlear implant surgery are also included in this discussion.