Cerebellopontine angle lipoma: a rare differential diagnosis

Acoustic Neurinoma with Synchronous Ipsilateral Cerebellopontine Angle Lipoma: A Case Report and Review of the Literature

Lipomas of the cerebellopontine angle (CPA) and internal auditory canal (IAC) are relatively rare tumors. Acoustic neurinoma is the most common tumor in this location, which often causes hearing loss, vertigo, and tinnitus. Occasionally, this tumor compresses the brainstem, prompting surgical resection. Lipomas in this area may cause symptoms similar to neurinoma. However, they are not considered for surgical treatment because their removal may result in several additional deficits. Conservative therapy and repeated magnetic resonance imaging examinations for CPA/IAC lipomas are standard measures for preserving cranial nerve function. Herein, we report a case of acoustic neurinoma and CPA lipoma occurring in close proximity to each other ipsilaterally. The main symptom was hearing loss without facial nerve paralysis. Therefore, facial nerve injury had to be avoided. Considering the anatomical relationships among the tumors, cranial nerves, and CPA/IAC lipoma, we performed total surgical removal of the acoustic neurinoma. We intentionally left the lipoma untreated, which enabled facial nerve preservation. This report may be a useful reference for the differential diagnosis of similar cases in the future.

Internal Auditory Canal Lipoma: An Unusual Intracranial Lesion

BACKGROUND

Internal auditory canal (IAC) lipomas are rare intracranial lesions. Consequently, preoperative imaging is essential in differentiating IAC lipomas from more common tumors such as vestibular schwannomas. The hallmark of lipomas on magnetic resonance imaging (MRI) is hyperintensity on T1-weighted images that suppresses on fat-suppressed sequences and does not enhance with gadolinium administration.

CASE DESCRIPTION

The present case describes a 53-year-old woman who was misdiagnosed with a vestibular schwannoma because of the lack of appropriate MRI sequences.

CONCLUSIONS

This case demonstrates the importance of ensuring that both fat-suppressed and non-fat-suppressed T1-weighted pregadolinium images are obtained in the diagnostic process of IAC lesions. It is therefore recommended that imaging centers ensure that such sequences are included in their MRI protocols.

Diagnostic Dilemma: Cerebellopontine Angle Lipoma Versus Dermoid Cyst

Both lipomas and dermoid cysts of the cerebellopontine angle are rare tumors. These tumors differ in their embryological origin but share similar features on imaging. Both of these congenital lesions can be found in the cerebellopontine angle (CPA), and symptomatic clinical presentation is dictated by the location of the lesion. This paper demonstrates a unique case in which a CPA lipoma was misidentified as a dermoid cyst, leading to surgical intervention. Further, the paper provides a literature review of CPA lipomas and dermoid cysts to aid readers in further differentiating between these two unique tumors.

Evaluating the utility of a scoring system for lipomas of the cerebellopontine angle

BACKGROUND

Cerebellopontine angle (CPA) lipomas are rare, benign, slow-growing masses. Resections are considered in symptomatic patients who are refractory to targeted medical therapies, but at those stages the lipomas have often reached considerable sizes and encompass critical neurovascular structures. The objective of this study is to develop and to evaluate the utility of a scoring system for CPA lipomas. The hypothesis is that CPA lipomas with lower scores are probably best managed with early surgery.

METHODS

The PubMed database was searched using relevant terms. Data on patient and lipoma characteristics were extracted and used to design a scoring system. CPA lipomas were stratified by scores with corresponding managements and outcomes analyzed.

RESULTS

One hundred and seventeen patients with CPA lipomas were identified and 40 CPA lipomas were scored. The remaining CPA lipomas were deficient in data and not scored. No lipomas were scored as 1. Score 2 lipomas (n = 12; 30%) most often underwent serial surveillances (n = 5; 41.6%), with the majority of symptoms remaining unimproved (n = 2; 40%). Patients with score 2 CPA lipomas treated with medical therapies (n = 3; 25%) often experienced symptom resolution (n = 2; 66.6%) (p = 0.0499). Patients with score 2 CPA lipomas undergoing surgical resections (n = 3; 25%) all experienced symptom resolution (n = 3; 100%) (p = 0.0499). Score 3 was most common (n = 16; 40%) and these lipomas were often surgically resected (n = 10; 62.5%). The majority of patients with score 3 CPA lipomas having undergone surgical resections (n = 10; 62.5%) experienced symptom improvement (n = 1; 10%) or resolution (n = 4; 40%).

CONCLUSIONS

Score 2 CPA lipomas are smaller and would be deemed non-surgical in general practice. However, our data suggest that these lipomas may benefit from either medical therapies or early surgical resections. The advantages of early surgery are maximal resection, decreased surgical morbidity, and improved symptom relief.

Lipomatosis of the trigeminal nerve causing trigeminal neuralgia: case report and literature review

Cerebellopontine angle lipomas are rare and attempts at surgical excision are associated with significant morbidity. Lipomatosis of nerve, the fatty infiltration of nerves, is a distinct entity. We present a case of intractible trigeminal neuralgia caused by lipomatosis of the trigeminal nerve.

CLINICAL CASE

A 25-year-old male presented with severe right-sided trigeminal neuralgia. Imaging showed a lesion involving the trigeminal nerve with signal characteristics of fat. At surgery the lesion was found to be a fatty infiltration of the nerve itself. Surgery was therefore limited to arachnoid adhesiolysis. The patient remains symptom-free and neurologically intact to date. Correctly identifying these lesions as lipomatosis of nerve rather than lipoma of the cerebellopontine angle make it clear that even partial surgical excision will inevitably result in neurological deficit and should not be attempted. However, in the case of intractable trigeminal neuralgia we demonstrate that surgery can still play a role.

Rare Bilateral Lipoma of the Internal Auditory Canals

About 10% of all intracranial tumors are localized in the cerebellopontine angle and in the internal auditory canal. Less than 2% of these are lipomas. Furthermore, it can be expected that lipomas in this position with a bilateral localization are exceedingly rare. We describe a 70-year-old-woman with lipomas in both internal auditory canals presented in the literature for the first time and include a detailed literature research.

Infratentorielle Tumoren

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

Cerebellopontine Angle Lipomas: Report of Four Cases and Review of the Literature

OBJECTIVE:

To define the management of internal acoustic meatus and cerebellopontine angle (CPA) lipomas according to their clinical, histological, and surgical characteristics.

METHODS:

We report four new cases of CPA lipomas diagnosed in the Department of Otorhinolaryngology–Head and Neck Surgery of Hôpital Pitié-Salpêtrière and review 94 cases reported previously in the literature.

RESULTS:

Lipomas represented 0.14% of CPA and internal acoustic meatus tumors. Localization was on the left side in 59.9%, on the right side in 37%, and bilateral in 3.1% of the patients. The diagnosis was confirmed radiologically in 33 of 98 patients, surgically in 60 patients, and by autopsy in 5 patients. The most frequent associated symptoms were of cochleovestibular origin, such as hearing loss (62.2%), dizziness (43.3%), and unilateral tinnitus (42.2%). Other associated symptoms involved the facial nerve (9%) or the trigeminal nerve (14.4%). Complete resection was performed in only 32.8% of the patients with frequent cranial nerve involvement. Frequent cranial nerve involvement was seen in 95.4% of all patients. After surgery, patient symptomatology was unchanged in 9.2% of the patients, and 50% were improved; however, new postoperative deficits occurred in two-thirds of the patients. Overall, 72.2% of the patients experienced new postoperative deficits such as hearing loss (64.8%). Preservation of hearing was possible in only 26% of the patients. Only 18% of patients were improved after surgery without any new postoperative deficits.

CONCLUSION:

Preoperative diagnosis of internal acoustic meatus/CPA lipomas is based on magnetic resonance imaging. The aim of surgery in these cases is not tumor removal but cranial nerve decompression or vestibular transection, and surgery is performed only in patients with disabling and uncontrolled symptoms.

[Cerebellopontine angle lipoma: clinical case]

Lipomas of the cerebellopontine angle are extremely rare. These tumors are probably maldevelopment lesions which can cause slowly progressive neurological symptoms. Including the present case, 90 lipomas in this localization have been described in the literature. The authors report a case of cerebellopontine angle lipoma in a 44-year-old male patient who suffered right hearing loss and tinnitus during seven months. The literature concerning this rare cerebellopontine angle tumor is review. The symptoms, radiological features and surgical management are discussed.

Lipomas of the internal auditory canal and cerebellopontine angle

OBJECTIVE

To evaluate lipomas of the internal auditory canal (IAC) and cerebellopontine angle (CPA).

STUDY DESIGN

Retrospective review.

METHODS

Review of a multi-institutional series of 17 lipomas of the IAC/CPA, combined with a Medline review of the 67 cases reported in the world literature.

RESULTS

This series of 17 IAC/CPA lipomas is the largest reported series to date, bringing the total number of documented cases to 84. There appears to be a nearly 2:1 male to female predominance. Sixty percent were left-sided lesions, and three were bilateral. Hearing loss, dizziness, and tinnitus were the most common presenting symptoms. Surgical resection was performed in 52 (62%) of these lesions; however, total tumor removal was accomplished in only 17 (33%), which is most likely because of the fact that these tumors tend to have a poorly defined matrix and a dense adherence to neurovascular structures. Sixty-eight percent of patients experienced a new deficit postoperatively, 11% were unchanged, and only 19% improved with no new deficit. Only one documented case of tumor growth was identified; however, the reported follow-up was short (average, less than 3 years).

CONCLUSION

With the magnetic resonance imaging techniques now available, lipomas can be reliably differentiated from other masses within the CPA and IAC, so histopathologic diagnosis is rarely necessary. Because of the potential for significant morbidity with resection of these lesions, we believe that conservative follow-up is the best treatment option for patients with these rare lesions. Surgery is indicated only when significant progressive or disabling symptoms are present.