Lipomas of the cerebellopontine angle and internal auditory canal

Lipoma Of The Internal Auditory Canal: An Uncommon Cause Of Unilateral Deafness And Dizziness

Lipomas inside the internal auditory canal are infrequent. We describe a 43 years old woman who complains about sudden unilateral deafness, tinnitus and dizziness. With CT and RMN we make a certain diagnosis of lipoma inside the internal auditory canal. Due to the absence of limitations, we offer an annual follow up for assessing the patient's clinical situation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-022-03351-3.

A case report of a Cerebellopontine angle lipoma revealed by vertigo

Cerebellopontine angle (CPA) lipoma is an extremely rare lesion representing only 0.1% of all the CPA tumors. We present a case of a 56-year-old woman with a 6-month history of vertigo. Cerebral MRI showed a left CPA lipoma. The patient was managed conservatively.

Cerebellopontine Angle and Internal Auditory Canal Lipomas: Case Series and Systematic Review

OBJECTIVES/HYPOTHESIS

Cerebellopontine angle (CPA) and internal auditory canal (IAC) lipomas are rare, benign tumors comprising 0.08% of all intracranial tumors and can be mistaken for other, more common lesions of the CPA/IAC such as vestibular schwannoma. The purpose of this study was to review the literature and assess the evolution of CPA/IAC lipoma diagnosis and management. In addition, we present 17 new lipomas, matching the largest known case series of this rare tumor.

STUDY DESIGN

Retrospective case series and systematic review.

METHODS

Systematic review of the literature was performed using PubMed and Google Scholar. References from identified articles were also reviewed to identify potential additional manuscripts. Manuscripts and abstracts were reviewed to identify unique cases. For the case series, the charts of all CPA/IAC lipoma patients seen at a single institution from 2006-2019 were manually reviewed. Logistic regression and chi-squared analysis were performed where appropriate.

RESULTS

A total of 219 unique lipomas have been reported in the literature, including 17 presented in this study. Surgical management has been performed in 46% of cases and has been conducted less often in recent decades, likely due to improved radiographic diagnostic capabilities and understanding of surgical outcomes. Surgical management is associated with worse neurologic outcomes (P = .002) and has become less common in recent decades. Although growth is unlikely, it has been demonstrated in patients into their 30s.

CONCLUSIONS

Accurate radiographic diagnosis is imperative for appropriate patient management, as CPA/IAC lipomas should typically be managed through observation and serial imaging whereas vestibular schwannomas and other CPA/IAC lesions may require microsurgical or radiosurgical intervention depending on growth and symptomatology. Laryngoscope, 131:2081-2087, 2021.

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.

Middle ear lipoma mimicking a congenital cholesteatoma: A case report and review of the literature

OBJECTIVE

To describe a case of middle ear lipoma, review the current literature, and discuss the surgical approach.

METHODS

Published case reports in the English literature of lipomas restricted to the middle ear were reviewed. The presentation, location, and management of the middle ear lipomas were analyzed.

RESULTS

Histological examination of the resected middle ear lesion was compatible with lipoma. Review of the literature suggests middle ear lipomas are rare and involve the epitympanum.

CONCLUSION

Lipomas should be included in the differential diagnosis for middle ear lesions. Adequate surgical exposure can be achieved through a transcanal approach, with particular attention to carefully elevate the tympanic membrane off the malleus, preserving the integrity of the ossicular chain.

Lesions Mimicking Small Vestibular Schwannomas

Objective  Most tumors of the internal auditory canal and cerebellopontine angle (CPA) are vestibular schwannomas (VSs). Preoperative diagnosis is based on typical clinical symptoms and radiological findings. In rare cases, histopathology can, however, show different results. Design  This is a retrospective chart and database review. Setting  The study was conducted at a tertiary skull base referral center at a university hospital. Participants  A total of 207 consecutive cases of VS surgery via the middle cranial fossa approach performed between December 2005 and January 2015 were reviewed. Main Outcome Measures  The main outcome measures were definitive histologic findings in 198 specimens, analysis of preoperative magnetic resonance imaging (MRI) and computed tomography. Results  Histopathology revealed three meningiomas and two cases of lipochoristomas. Clinical presentation was typical for VS in all five cases. In preoperative MRI, all tumors were suspected to be VSs. Retrospective analysis of the preoperative imaging did not lead to a modification of the diagnosis. Intraoperative findings showed increased adherence of the tumor to the adjacent tissue in two of the five cases. Conclusion  CPA lesions other than VSs are unusual but have to be taken into account. In very small tumors, imaging still remains difficult.

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.

Lipochoristoma of the Internal Auditory Canal

Objective Lipochoristomas comprise 0.1% of all cerebellopontine angle tumors and may be misdiagnosed as vestibular schwannomas. We describe a lipochoristoma of the internal auditory canal (IAC) and present the salient features of the evaluation, diagnosis, and management.

Study Design and Methods Retrospective case review.

Results (Case Report) A 51-year-old woman presented with left-sided severe hearing loss, tinnitus, mild episodic vertigo, and facial paresthesias progressive over 1 year. Magnetic resonance imaging (MRI) demonstrated a small (5 × 4 mm) T1 hyperintense lobulated lesion in the distal internal auditory canal. With fat-suppressed images, there was no enhancement of the lesion. A diagnosis of IAC lipochoristoma was made. Conservative management was recommended, and on 17-month follow-up there was no interval growth. The patient remains symptomatically stable with improved equilibrium but persistent left-sided hearing loss.

Conclusions Differential diagnosis of an enhancing lesion in the IAC includes acoustic neuroma, meningioma, epidermoid and arachnoid cysts, lipochoristoma, and metastatic tumors. Fat-suppressed MRI sequences aid in a definitive diagnosis of lipochoristomas. Because lipochoristomas may have a tendency for more indolent growth and intimate involvement of the auditory nerve, conservative management with interval imaging is recommended. Surgical treatment is reserved for growing lesions or those with disabling vestibular symptoms.

Cerebellopontine angle and intracanalicular masses mimicking vestibular schwannomas

OBJECTIVE

To describe the clinical and radiographic characteristics in a series of patients with non-vestibular schwannoma cerebellopontine angle (CPA) and intracanalicular (IAC) masses, who underwent microsurgery for presumed vestibular schwannoma (VS).

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary neurotologic referral center.

PATIENTS

One thousand five hundred ninety-three patients underwent microsurgery for apparent VS from 2002 to 2013. Of these, 53 patients (3%) were discovered to have a diagnosis other than VS.

INTERVENTIONS

Middle fossa, translabyrinthine, and retrosigmoid craniotomy.

MAIN OUTCOME MEASURES

Clinical presentation, radiologic analysis, and histopathology examination.

RESULTS

There were 17 facial schwannomas, 15 meningiomas, 9 hemangiomas, 6 lipochoristomas, 3 inflammatory reactions, and one each of lymphoma, glial heterotopia, solitary fibrous tumor, ependymoma, and a non-diagnostic mass. Excluding facial schwannomas, 23 cases were misdiagnosed as VS in the first half of the study period, compared to only 15 cases in the latter half (p = 0.09). Ninety-six percent of patients presented with some combination of sensorineural hearing loss, balance disturbance, and tinnitus. In the subset of patients with available preoperative MRI scans for retrospective review, only 4 of 28 patients had radiologic findings suggestive of pathology other than VS. The most common missed radiologic diagnoses were facial schwannoma, lipochoristoma, and meningioma.

CONCLUSION

A subgroup of patients with CPA and IAC masses who present with radiologic findings diagnostic of VS will have an alternative histopathologic diagnosis. Optimal radiologic imaging and experienced interpretation can improve diagnostic accuracy. The most common tumors that mimic VS despite ideal radiologic imaging are facial schwannomas, meningiomas, and hemangiomas.

Lipoma causing glossopharyngeal neuralgia: a case report and review of literature

The cerebello-pontine angle lipomas causing trigeminal neuralgia or hemifacial spasm are rare. A lipoma causing glossopharyngel neuralgia is also very rare. A 46-year-old woman complained of 2-year history of severe right throat pain, with ipsilateral episodic otalgic pain. The throat pain was described as an episodic lancinating character confined to the throat. Computed tomography and magnetic resonance imaging revealed a suspicious offending posterior inferior cerebellar artery (PICA) compressing lower cranial nerves including glossopharyngeal nerve. At surgery, a soft, yellowish mass (2×3×3 mm in size) was found incorporating the lateral aspect of proximal portion of 9th and 10th cranial nerves. Only microvascular decompression of the offending PICA was performed. Additional procedure was not performed. Her severe lancinating pain remained unchanged, immediate postoperatively. The neuralgic pain disappeared over a period of several weeks. In this particular patient with a fatty neurovascular lump causing glossopharyngeal neuralgia, microvascular decompression of offending vessel alone was enough to control the neuralgic pain.

Symptomatic Lipoma of the Internal Auditory Canal: CT and MRI Findings. A Case Report

We describe the case of a 39-year-old man in whom diagnostic work-up for combined right-sided hearing loss revealed a lipoma of the internal auditory canal (IAC). This very rare diagnosis has significant implications for therapeutic management because lipomas, unlike other lesions in the IAC, should not be surgically removed in most cases. We emphasize the importance of the combined use of magnetic resonance imaging and computed tomography to reliably establish the diagnosis of a lipoma, differentiate it from other potential lesions of the internal auditory canal, and exclude additional pathologies in the petrosal bone.

CT and MR Imaging Characteristics of Intravestibular and Cerebellopontine Angle Lipoma

Intracranial lipoma is an uncommon entity. A rare type of tumor in the internal auditory canal (IAC) and the cerebellopontine angle (CPA) is lipoma. There are a few case reports in the literature related to intravestibular lipoma. Herein, we report a case of lipomas within the cerebellopontine angle and vestibule of the inner ear in a patient with tinnitus and dizziness. The patient was evaluated with a 1.5 T magnetic resonance imaging (MRI) system. MRI and CT showed the masses in the left CPA and the left IAC. These lesions were hyperintense on both T1- and T2 weighted images and showed no enhancement after gadolinium administration. Conservative management was suggested. Histopathological diagnosis is rarely necessary with the widespread use of magnetic resonance imaging. Considering significant morbidity during resection, conservative follow-up is the best approach for CPA and IAC lipoma.

Management of cerebellopontine angle lipomas: need for long-term radiologic surveillance?

OBJECTIVE

To date, only a very limited number of lipomas of the cerebellopontine angle (CPA) have been reported. Our objective was to examine clinical and radiologic features of CPA lipomas and determine the most appropriate management plan.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

Patients with CPA lipomas were identified through the skull base multidisciplinary meeting database.

INTERVENTIONS

Radiologic surveillance and clinical assessment.

MAIN OUTCOME MEASURES

Tumor growth, assessed through radiologic measurements on serial magnetic resonance imaging, demographics, presenting symptoms, and any correlation between weight gain and lipoma growth were among the examined factors.

RESULTS

Of the 15 patients with CPA lipomas, six were female and nine were male, with an average age at presentation of 50.2 years (range, 31.7-76.4 yr) and an average follow-up time of 51.7 months (range, 6-216 mo). The lipomas were unilateral in all cases, nine on the right (60%) and six on the left (40%) side. None of the lipomas increased in size. All patients were treated conservatively. Sensorineural hearing loss was the main presenting symptom (80%) followed by tinnitus (46.7%) and vertigo (20%). None of the patients suffered from facial nerve dysfunction. There was no correlation between weight gain and tumor growth.

CONCLUSION

CPA lipomas can be diagnosed accurately with appropriate magnetic resonance imaging techniques and be managed conservatively with safety. Cochleovestibular are the most common presenting symptoms, whereas facial nerve involvement is rare. CPA lipomas do not tend to grow and can be monitored on a less regular basis.