Intraparotid facial nerve schwannoma: literature review and classification proposal

Ancient schwannoma in the parotid gland: A case report and review of the literature

Schwannomas are uncommon neoplasms of neurologic origin that are rare in the salivary glands. A schwannoma that persists for a long time is referred to as an ancient schwannoma if it is accompanied by degenerative changes on histology. The case described herein involved a 37-year-old man with an ancient schwannoma that had persisted for 20 years in his right parotid gland. Clinically, the lesion presented with swelling and pain. Computed tomography revealed a well-defined, multilocular enhanced lesion. T2-weighted magnetic resonance images displayed multilocular hyperintensity, while T1-weighted images showed a high signal at the lobulated margin and a homogeneous low signal internally. The preoperative diagnosis, based on the lesion's location and imaging diagnosis, was Warthin's tumor. However, a biopsy conducted after surgical excision identified the lesion as a schwannoma with cystic degeneration. This report also presents a summary of the characteristics of rare cases of schwannoma in the major salivary gland based on this case and a literature review.

Extracranial Facial Nerve Schwannoma-Histological Surprise or Therapeutic Planning?

Schwannomas (neurilemomas) are benign, slow-growing, encapsulated, white, yellow, or pink tumors originating in Schwann cells in the sheaths of cranial nerves or myelinated peripheral nerves. Facial nerve schwannomas (FNS) can form anywhere along the course of the nerve, from the pontocerebellar angle to the terminal branches of the facial nerve. In this article, we propose a review of the specialized literature regarding the diagnostic and therapeutic management of schwannomas of the extracranial segment of the facial nerve, also presenting our experience in this type of rare neurogenic tumor. The clinical exam reveals pretragial swelling or retromandibular swelling, the extrinsic compression of the lateral oropharyngeal wall like a parapharyngeal tumor. The function of the facial nerve is generally preserved due to the eccentric growth of the tumor pushing on the nerve fibers, and the incidence of peripheral facial paralysis in FNSs is described in 20-27% of cases. Magnetic Resonance Imaging (MRI) examination is the gold standard and describes a mass with iso signal to muscle on T1 and hyper signal to muscle on T2 and a characteristic "darts sign." The most practical differential diagnoses are pleomorphic adenoma of the parotid gland and glossopharyngeal schwannoma. The surgical approach to FNSs requires an experienced surgeon, and radical ablation by extracapsular dissection with preservation of the facial nerve is the gold standard for the cure. The patient's informed consent is important regarding the diagnosis of schwannoma and the possibility of facial nerve resection with reconstruction. Frozen section intraoperative examination is necessary to rule out malignancy or when sectioning of the facial nerve fibers is necessary. Alternative therapeutic strategies are imaging monitoring or stereotactic radiosurgery. The main factors which are considered during the management are the extension of the tumor, the presence or not of facial palsy, the experience of the surgeon, and the patient's options.

Systematic Review of Intra Parotid Facial Nerve Schwannoma and a Case Report

To evaluate the clinico-epidemiological aspects, pathological features, diagnostic methods, management protocol and functional outcome of the intra-parotid facial nerve schwannoma (IFNS) and to present a case report on intra parotid facial nerve schwannoma. PubMed, ProQuest, Google scholar, Science direct and Scopus were screened for studies. Article selection and data extraction was done by one investigator and other investigator confirmed its accuracy. After abstract and text screening a total of 69 articles were finally selected for the study with the inclusion and exclusion criteria of the systematic review as per PRISMA guidelines. With addition of one case reported to our department. The mean age of diagnosis was 43 ± 16 years with a slight female predominance. The mean duration of the tumour was 29.5 months and the mean size of the tumour on initial diagnosis was 3.6 ± 1.67 cm. Pleomorphic adenoma was the primary diagnosis in 44 cases. Superficial parotidectomy was done in 64 cases followed by resection in 47 cases. Reconstructive treatment was carried out by an end-to-end anastomosis in 3 patients and by facial-hypoglossal anastomosis in 16 patients, GAN cable grafting in 5 patients, a greater auricular nerve graft was done in18 patients and end-to-side interposed sural nerve graft in 8 patients. The type D tumours are treated by extended resection of the facial nerve, which is difficult to reconstruct and also employs a nerve graft that does not often give acceptable recovery of facial function. Facial nerve schwannomas being a rare entity poses a dilemma in diagnosis and management. Managing the lesions is also difficult as intraoperative adherence to the nerve makes a tumour free margin difficult without sacrificing the nerve. At present there is no consensus regarding the management of various types of intra-parotid facial nerve shwannoma.

Rare Schwannomas of Head and Neck and Review of Literature

Benign schwannoma is a slow growing encapsulated tumor arising from the sheath of Schwann, The majority had extra-cranial localization. We report in this review three cases of a rare extra cranial localization of benign schwannoma in the trachea, frontal sinus and intraparotid facial nerve. The first case diagnosed in a 10-years-old boy, presented with a painless, slow growing mass evolving for three years in the left parotidic region, total conservative parotidectomy was done. The second case concerned a 38-years-old, was admitted to the emergency department with acute inspiratory dyspnea, endoscopic exploration revealed a polylobed tracheal tumor, complete tumor excision was done endoscopically. The third case was about a 33 years old patient, presented a gradually enlarging frontal swelling associated with headache and left nasal obstruction, the endoscopic examination revealed a gray pinkish, smooth and firm soft tissue mass occupying the entire left nasal cavity, CT scan and MRI were requested to assess the characteristics and extent of the tumor, The surgical intervention combined two approaches: trans facial through a mid-frontal incision, and endonasal one. Histopathological examination confirmed the diagnosis of benign schwannoma in all these cases.

Preauricular Intraparotid Schwannoma: A Rare Presentation with Literature Review

Schwannoma is a benign tumor rarely found in the intraparotid facial nerve region. It clinically presents as a slow-growing, asymptomatic mass. Due to its rare presentation, preoperative diagnosis is often unclear before surgical removal and histopathological examination. Imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) play an important role in suggesting the nature of mass and narrowing down the differentials. The CT scan offers the advantage to detect the relationship of the facial nerve and osseous changes within the bone, however MRI shows a mass relative to brain type of tissue. We report a rare case of intraparotid facial nerve schwannoma in a 17-year-old female who had sustained swelling in her left preauricular area for 5 years. Ultrasonography and CT findings revealed the impression of pleomorphic adenoma. However, MRI and histopathological findings were characteristic of schwannoma. Thus, this article provides an insight into a rare presentation of schwannoma with literature review.

Extratemporal intraparotid facial nerve schwannoma

Schwannomas of the eighth nerve are common, usually found in syndromic association with neurofibromatosis-2. The occurrence of seventh nerve schwannoma, especially in its extratemporal course, is very rare. Here, we present a case report of an extratemporal facial nerve schwannoma diagnosed preoperatively with cytopathology and postoperative histopathologic confirmation. Histopathology provides the confirmatory diagnosis in such cases. An atypical diagnosis of neural schwannomas should be kept in mind when facial palsy is clinically encountered in the absence of any other aetiological factors.

Intraparotid facial nerve schwannoma: a 17-year, single-institution experience of diagnosis and management

BACKGROUND

Intraparotid facial nerve schwannoma (IFNS) is rare and its definite preoperative diagnosis is challenging.

OBJECTIVE

To improve available knowledge regarding the diagnosis of IFNS and to suggest an appropriate treatment plan.

MATERIAL AND METHODS

We retrospectively analyzed medical records of IFNS patients at our hospital. Inclusion criteria were surgery (from January 2000, to December 2016) for a parotid mass, pathologically diagnosed as a schwannoma.

RESULTS

The study included 42 eligible patients who had undergone tumor resection from 5977 parotid tumor patients. Mostly presented hard-textured (18/39) or medium-textured (15/39), with limited mobility (21/39) mass (three tumors were not palpable). Their facial nerve function outcomes were House-Brackmann Grade I (n = 14), Grade II (n = 7), Grade III (n = 11), Grade IV (n = 5), Grade V (n = 3), and Grade VI (n = 2). Significant differences were noted in results based on different surgical methods used (p = .000) and tumor involvement (p = .002).

CONCLUSIONS AND SIGNIFICANCE

A hard-textured tumor with limited mobility mass in the parotid gland should prompt the diagnosis of a schwannoma. Tumors involving main trunk usually lead to unsatisfactory facial nerve outcomes. Facial nerve preservation should always be essential, and stripping surgery or intracapsular enucleation could be the preferred surgical methods of choice.

Intraparotid facial nerve schwannoma: two case reports and a review of the literature

SUMMARY

Schwannomas are rare benign tumours that arise from Schwann cells. The most known and studied is the intracranial vestibular schwannoma, even if it is not the most frequent. More often schwannomas arise from peripheral sensitive nerves, and the vagous is most involved among the cranial nerves. Intraparotid schwannomas account for just 10% of all facial involvement, so they are an extremely rare localisation. At present, there are less than 100 cases described in the literature. We performed a retrospective analysis of parotidectomy in two Italian hospitals and present two cases of intraparotid schwannoma and a review of the literature. In the first case, we performed a parotidectomy with a stripping of tumour from the nerve. In the other case, a hypoglossal-facial neurorrhaphy was performed. Follow-up was 24 months in the first (House-Brackmann II degree in temporal-ocular and III in facial-cervical branches) and 30 months in the second case (House-Brackmann III degree in both temporal-ocular and facial-cervical branches). Preoperative diagnosis of facial nerve schwannoma is a challenge; however, it is extremely important since post-operative palsy is common and often higher grade. Unfortunately, schwannoma has similar radiologic finding as more common pleomorphic adenoma and often FNAC is not helpful. Due to its rarity and benign nature, there is debate in the literature on the need for surgical removal. Wait-and-see is a valid option, but may could give problems in secondary surgery. Stripping or near-total removal can be useful in cases of limited involvement of the nerve. Neurorrhaphy can provide good functional results when facial sacrifice is needed.

Intraparotid facial nerve schwannomas

Schwannoma is a benign tumor rarely found in the head and neck and much less commonly found in the intraparotid facial nerve. It is a slow-growing encapsulated tumor originating from the Schwann cells or axonal nerve sheath. It can occur anywhere along the course of the facial nerve. Patients may present with symptoms of facial palsy, but the most common presenting symptom is an asymptomatic swelling. Diagnosis is usually difficult before surgical removal and histopathological examination. We report a rare case of intraparotid facial nerve schwannoma in a 57-year-old female who had sustained a mass of the right preauricular area for 3 years. She reported no pain or facial muscle weakness. Enhanced computed tomography findings revealed the impression of pleomorphic adenoma. However, intraoperative gross findings were not characteristic of pleomorphic adenoma, and a frozen biopsy was performed resulting in the impression of a nerve sheath tumor. We performed an extracapsular surgical excision without parotidectomy. Permanent histopathology and immunohistochemistry reports diagnosed the mass as schwannoma. There were no complications including facial palsy after surgery. No recurrence was found at 6 months after surgery.

Facial Paralysis Following Core Needle Biopsy of a Deep Lobe Parotid Tumor: A Case Report

Objectives:

To report a case of total facial paralysis as the result of a core needle biopsy.

Methods:

Case report and literature review.

Results:

A 70-year-old man was diagnosed with a deep lobe parotid tumor on computed tomography. During a core needle biopsy, he developed complete facial paralysis. The cause was discovered to be a direct stab injury to the main trunk of the facial nerve.

Conclusions:

When biopsying parotid lesions adjacent to the main trunk of the facial nerve, the use of smaller-gauge needles and additional patient counseling should be considered.

Intraparotid Facial Nerve Schwannoma in a Nine-Year-Old Patient: Diagnosis, Classification, and Surgical Approach Stages

Intraparotid facial nerve schwannoma (IFNS) is rarely observed in children compared with adults. Only a few cases have been reported in the literature. After radiological imaging and fine needle aspiration biopsy, an IFNS diagnosis may be skipped and confused with pleomorphic adenoma, which has a high prevalence among patients who have a mass in the parotid gland. The probability of IFNS can be recognized by a close relation between the mass and the facial nerve during the application of parotidectomy and by the frozen biopsy of the mass. The surgeon evaluates the mass and faces with surgical mass excison and facial nerve reconstruction according to the relation between the mass and the facial nerve because there is no diagnostic method for the presurgery diagnosis of IFNS. Therefore, the surgeon should be prepared for the possibility of functional lossin the facial nerve during parotidectomy. This article presents the case of a 9-year-old patient with an IFNS diagnosis who had a surgical operation in our clinic, and the algorithm designed according to the literature for the diagnosis and surgical classification of IFNS, as well as the approaches to facial nerve reconstruction.

Pediatric Intraparotid Neurofibroma: Rare Entity

Aim: This case report provide an awareness of intraparotid facial nerve neurofibroma as a cause of parotid masses and to describe their characteristics and management considerations. Material: It is a case report of a pediatric patients with intraparotid facial nerve neurofibromas which is a rare entity. Method: It was preoperatively diagnosed as intraparotid benign tumor likely to be pleopmorphic features on fine needle aspiration cytology.Tumors arising from the extratemporal course of the facial nerve are quite rare. The tumors arise from Schwann cells and include the schwannoma and the neurofibroma. Conclusion: The overwhelming benign nature of these lesions necessitates a conservative course of treatment. Histological diagnosis should be followed by a limited tumor excision with emphasis on retaining normal facial nerve function. Malignant lesions require wide excision with facial nerve grafting or facial nerve reanimation.

Clinical Retrospective Analysis of 9 Cases of Intraparotid Facial Nerve Schwannoma

PURPOSE

The management of intraparotid facial nerve schwannoma (IFNS) is challenging because it is extremely rare and often misdiagnosed as pleomorphic adenoma or another parotid tumor. The purpose of this study was to report on the authors' experience in the treatment of IFNS and to review the literature regarding the diagnosis and management of IFNS.

MATERIALS AND METHODS

From January 1997 through October 2015, 916 consecutive parotidectomies were performed at Shenzhen People's Hospital (Shenzhen, China). Of 916 parotid tumors samples, 9 cases of IFNS confirmed by histopathology were identified and analyzed retrospectively. In addition, 161 published cases from 1956 through 2015 were systematically reviewed.

RESULTS

Nine cases of IFNS were identified from 916 parotid tumors samples and accounted for 0.98% of all parotid tumors. All these patients with IFNS underwent tumor removal and parotidectomy with preservation of facial nerve (FN) continuity. The mean follow-up period was 6.2 years (range, 1 to 16 yr). Facial function improved gradually from House-Brackmann grade (HBG) II to III immediately postoperatively to HBG I during the subsequent 3 to 9 months in all cases. Tumor recurrence with stylomastoid foramen involvement was observed in 1 case 3 years after surgery. The others remained free of recurrence. Of 161 IFNS cases reported in the literature, 17 cases with facial paresis were found to have intra-temporal involvement, but no facial paresis was found in patients with intraparotid involvement only.

CONCLUSIONS

An IFNS is easily misdiagnosed as pleomorphic adenoma or Warthin tumor preoperatively; the correct diagnosis for IFNS depends mainly on intraoperative observation of the gross relation between the tumor and the FN or excision frozen biopsy examination. The integrity of the FN should be preserved for patients with IFNS and without facial paresis, whenever possible.

Facial Nerve Schwannoma of Parotid Gland: Difficulties in Diagnosis and Management

Facial nerve schwannomas (FNS) are encapsulated benign tumors arising from Schwann cells of seventh cranial nerve. Most of the facial nerve schwannomas are localized in intratemporal region; only 9% of cases involve a portion of the extratemporal segment. Preoperative diagnosis is often unclear; diagnosis is often made intraoperatively. Management of intraparotid FNS is troublesome because of the facial nerve paralysis. In this report we presented a case of intraparotid schwannoma in a 55-year-old male patient complaining of a painless mass without peripheral facial nerve palsy in left parotid gland. Clinical features, preoperative and intraoperative diagnosis, and difficulties during management are discussed with the review of the literature.

Intraparotid schwannoma

Diagnoses most commonly associated with a unilateral parotid mass include sialadenitis, pleomorphic adenoma, Warthin tumor, and mucoepidermoid carcinoma. However, rare entities, such as intraparotid schwannoma, must be considered in the differential diagnosis. We present a brief literature review that is illustrative of the current difficulty of preoperative diagnosis of intraparotid schwannoma, which is an exceptionally rare entity, with approximately 80 cases described to date. It may mimic common neoplasms and inflammatory salivary gland conditions on fine-needle aspiration and imaging, but is more likely to be associated with the facial nerve. Depending upon the tumor's spatial relationship to the facial nerve and the extent of neurologic dysfunction, the decision may be made to observe the tumor rather than attempt resection. This potential implication for patient management is a critical consideration that highlights the need for timely, appropriate biopsy and diagnosis.

Intraparotid Facial Nerve Schwannoma

Intraparotid facial nerve schwannoma is a rare benign neoplasm. Due to its rarity, it is not usually a prioritized diagnosis before surgery and may therefore lead to an unintentional treatment error. In this article, we report a single case of intraparotid facial nerve schwannoma. We were able to make a diagnosis with frozen biopsy. A complete resection of the mass while preserving the facial nerve was performed. Herein we present our clinical experience with regards to the treatment process of intraparotid facial nerve schwannoma.

Management options for intraparotid facial nerve schwannoma

CONCLUSION

Limited intraparotid facial nerve schwannoma (IFNS) and IFNS with intratemporal involvement should be managed separately because of their different characteristics. Limited IFNS with House-Brackman (HB) grade ≤ II should undergo tumor removal only if it can be resected easily off the nerve. For IFNS with intratemporal involvement and a HB grade ≤ II, a conservative treatment (i.e. wait-and-see alone, or bone decompression) is recommended.

OBJECTIVE

To provide management options for IFNS.

METHODS

From 1996 to 2011, seven cases of IFNS underwent surgical treatment. Clinical and radiologic findings, surgical approach, and preoperative and postoperative facial nerve function were analyzed retrospectively.

RESULTS

Three IFNSs extended into the mastoid (43%). Two of the three patients with mastoid extension progressed to HB grade IV after the operation because the facial nerve was sacrificed, whereas the other one who underwent biopsy and decompression remained at HB grade II. Four limited IFNSs (57%) presented with grades I-II, three of which were removed while preserving facial nerve function and the other was removed by cystic decompression. No recurrence or significant growth of the non-resected schwannoma was observed.

The intraparotid facial nerve schwannoma: a diagnostic and management conundrum

OBJECTIVES

The aims of the study were (1) to review the management strategy and clinical outcomes of all intraparotid facial nerve (FN) schwannomas (PFNSs) treated at a single tertiary academic center from 1975 to 2010 and (2) to summarize all previously reported cases of PFNS in the international literature.

STUDY DESIGN

A retrospective cohort study and literature review.

METHODS

Fifteen patients were diagnosed and treated at the authors' institution from 1975 to 2010. In addition, 124 published cases were systematically reviewed.

RESULTS

The most common presentation of PFNS was a painless parotid mass with normal FN function. Eccentric, loosely attached intraparotid tumors underwent gross total resection with nerve preservation granting satisfactory postoperative FN function, whereas "inseparable" intraparotid tumors were observed in 8 cases with stable long-term size. Lesions that extended into the fallopian canal underwent complete resection with FN sacrifice and nerve grafting in 10 cases, whereas 1 patient received subtotal resection of the intraparotid portion with stereotactic radiotherapy targeting the intratemporal component.

CONCLUSIONS

Intraparotid FN schwannomas present similar to other primary salivary gland neoplasms, making an early diagnosis challenging. Intraoperative recognition of gross tumor characteristics and early histologic diagnosis with strategic biopsy are critical. Information including tumor location and extent, preoperative FN function, and the gross relationship between the tumor and the FN may guide the surgeon toward an optimal treatment plan emphasizing long-term neurologic preservation.

Management of facial nerve schwannoma: A single institution experience

CONCLUSION

Difficulties in diagnosis, conservative initial steps in the management algorithm and intraoperative risks for facial nerve (FN) injury are divisive features for this tumour entity.

OBJECTIVE

The aim of the present study was to investigate the management and outcome of FN schwannomas (FNSs) at a tertiary referral centre and academic institution in a 30-year material.

METHODS

Data on age, sex, symptoms, tumour location, histopathological characteristics, imaging, management and outcome were retrospectively recorded.

RESULTS

Ten cases (six males, 60%), with a median age of 34.5 years (range 19-75 years) were identified. Five of the patients had intact FN function at the time of diagnosis. Five of the tumours were intraparotid and five were located in the temporal bone. Preoperative fine needle aspirations were non-diagnostic in all of the four patients presenting with a parotid mass. Nine patients were managed surgically. One patient is currently under conservative follow-up for a parotid schwannoma (diagnosed with magnetic resonance imaging) with intact FN function. No malignant schwannomas were encountered. The clinical outcome and histology will be discussed.