Diagnostic Challenges and Imaging Considerations for Intraparotid Facial Nerve Schwannoma: A Case Report and Literature Review

BACKGROUND A mass in the parotid gland usually indicates parotid gland neoplasia. Warthin tumors or pleomorphic adenomas are common differential diagnoses. Less frequently, other differential diagnoses and sites of origin are considered. Schwannomas are rare, benign tumors in the head and neck region. Even more rarely, these tumors occur in the intraparotid course of the facial nerve. In the following, we report about 2 patients in whom a mass in the right parotid gland was found incidentally during magnetic resonance imaging (MRI). CASE REPORT We reviewed data from the literature on intraparotid facial nerve schwannomas (IPFNS) and compared them with those from our cases. The focus was on data such as clinical history, clinical symptoms, electroneurography, and various imaging modalities, such as ultrasonography and MRI combined with diffusion-weighted imaging. CONCLUSIONS It is challenging to distinguish facial nerve schwannomas from other neoplasms. Patient's history, clinical symptoms, MRI examination with diffusion-weighted imaging, and high-resolution ultrasound imaging are decisive factors for diagnosis and should be performed when IPFNS is suspected. Diagnosis and therapy for IPFNS remain challenging. A wait-and-scan approach could be an option for patients with small tumors and good facial nerve function. On the other hand, patients with advanced tumors associated with limited facial nerve function can benefit from surgical approaches or stereotactic radiosurgery.

A rare case of intraoral schwannoma in gingiva

BACKGROUND

Schwannomas are benign, slow-growing encapsulated nodular lesions. As for the most benign encapsulated lesions, the treatment of choice is complete removal of the entire tissue with preservation of surrounding tissue.

METHODS AND RESULTS

The case presented is that of a 35-year-old female with the chief complaint of swelling on her gums in the lower left posterior region. Through intraoral and extraoral examinations the benign nature of the lesion was established. The excisional biopsy was carried out under local anesthesia, and the specimen was sent for histological examination, which gave a definite diagnosis of oral schwannoma. The patient was recalled at regular intervals so as to check for any recurrence of the lesion or occurrence of new lesions elsewhere in the body.

CONCLUSION

The present case reemphasizes the importance of thorough clinical examination along with appropriate investigations, especially histopathological and immunohistochemical, for establishing a definitive diagnosis, which eventually plays an important role in the choice and execution of appropriate treatment at the earliest for the best prognosis and outcomes.

KEY POINTS

Why is this case new information? To the best of the author's knowledge, this the first case report of oral schwannoma diagnosed in gingiva in Indian population. This case presented a diagnostic dilemma due to its unusual location. What are the keys to successful management of this case? Schwannomas when completely excised have low rate of recurrence. Accurate diagnosis of the lesion along with complete physical examination and follow-up at regular interval to rule out any recurrences are the keys to successful management of this case. What are the primary limitations to success in this case? Lack of data regarding residual tumor postoperative is a primary limitations to success of the case, as recurrence is associated with subtotal tumor removal.

Hybrid peripheral nerve sheath tumours: MRI features with pathological correlation in 24 cases

OBJECTIVES

To describe the MRI features of histologically proven hybrid peripheral nerve sheath tumours (HPNST).

METHODS

A retrospective analysis of the MRI features of 24 histologically proven cases of HPNST over 7 years. Demographic data obtained from clinical records included age, gender, and date of diagnosis. Two readers independently assessed MRI studies and assessed the following features: involvement of a major nerve, intramuscular location, lesion morphology, entering nerve sign, exiting nerve sign, target sign, fascicular sign, split fat sign, and ancient change (cystic change). Inter-observer agreement was assessed with Cohen's kappa coefficient. Histological diagnosis was based on either image-guided needle biopsy or resection histology.

RESULTS

The study included 9 males and 15 females with mean age 50 years (range: 24-78 years). Nine tumours (35%) involved a major nerve including spinal roots (5), radial (1), median (1), tibial (1), and axillary (1), while 5 (21%) tumours were intramuscular. The mean tumour size was 4.2 cm (standard deviation of 2.4 cm). The frequency of MRI features was as follows: lobular contour (71%; 17/24), ancient change (38%; 9/24), fascicular sign (17%; 4/24), entering nerve sign (21%; 5/24), exiting nerve sign (13%; 3/24), target sign (13%; 3/24), and split fat sign (8%; 2/24). Inter-observer agreement was high, ranging from 0.7 to 0.83.

CONCLUSIONS

HPNST infrequently demonstrate the classical MRI signs of benign peripheral nerve sheath tumours, but commonly have a lobular morphology and can show ancient/cystic change.

ADVANCES IN KNOWLEDGE

This is the first study in the literature analysing the MRI features of histologically proven HPNST. HPNST infrequently shows the classical MRI signs that would be expected with benign peripheral nerve sheath tumours although commonly have a lobular morphology and show cystic change.

Cytological features of cranial and paraspinal nerve Tumours

The 2021 World Health Organization Classification of Central Nervous System Tumours introduced significant revisions to the categorization of paraspinal and nerve sheath tumours. This updated system encompasses seven tumour types: schwannoma, neurofibroma, perineurioma, hybrid nerve sheath tumours, malignant melanotic nerve sheath tumour, malignant peripheral nerve sheath tumour and cauda equina neuroendocrine tumour. This review provides an image-rich cytologic reference of these tumours, with particular emphasis on intraoperative smear preparations. Knowledge of the key cytological features of these tumours and their differential diagnoses will help guide classification of these challenging entities.

Perineurioma Diagnosed After Endoscopic Treatment of Suspected Gastric Adenocarcinoma of the Fundic Gland

Perineurioma is a relatively rare tumor with an occasionally difficult differential diagnosis. A 63-year-old woman underwent esophagogastroduodenoscopy, which revealed a 15 mm, slightly faded, flat, and elevated lesion in the gastric body. Biopsy revealed a bundle-like proliferation of spindle-shaped cells; however, the diagnosis was unconfirmed. Endoscopic submucosal dissection was performed for diagnosis and treatment. Histopathological examination of the lesion revealed cell proliferation with short spindle-shaped and oval nuclei and little atypia in the lamina propria. Immunohistochemical examination indicated a perineurioma. Thus, when spindle-shaped cells are found on biopsy, it is necessary to consider the possibility of perineurioma.

Mobile cauda equina schwannomas: How to deal with this rare event and avoid surgical complications

Background:

Mobile schwannomas of the cauda equina are rare. Preoperative planning should take into consideration the possibility of tumor migration, avoiding unnecessary additional laminectomy or second operation.

Case Description:

A patient with a previously known lumbar schwannoma was being managed conservatively until symptoms exacerbated and led to a new MR. When this study revealed caudal migration of the schwannoma from L3 to the L4–L5 levels, a right hemilaminectomy was performed for tumor resection.

Conclusion:

Great care must be taken in the surgical resection of schwannomas as they may migrate from their initial location.

Left Supraclavicular Swelling: Sclerosing Perineurioma

A sclerosing perineurioma presents as a single asymptomatic papule or nodule located on the hands of adult patients; approximately 60 cases have been reported in medical literature since 1997. Histologically, it originates from the perineural cells of the peripheral nerves and presents epithelial membrane antigen (EMA) positivity and S100 protein negativity. Here, we present the case of a 58-year-old male admitted to our surgery unit complaining of left supraclavicular swelling of 1-cm in size, having no significant past medical history. A lymph node neck tumor was suspected, and the patient underwent surgery under local anesthesia in outpatient care. The intraoperative finding was a whitish mass, wooden-fibrous in consistency, strictly adhering to the skin and apparently fixed to the deep planes. Upon histological examination, a sclerosing perineurioma was diagnosed: neoplastic cells were immunoreactive for CD34, CD99, and EMA, and negative for S100 protein, smooth-muscle actin, pancytokeratin (AE1-AE3), CD31, neurofilaments, and beta-catenin. According to the benign biological tumor behavior, radical resection was considered an adequate treatment. Our case presents as peculiarity the unusual non-acral location (first reported as supraclavicular swelling) and the rare immunopositivity for CD34 and CD99.

Total sacrectomy for low-grade malignant peripheral nerve sheath tumour: a case report

We report on a 58-year-old woman who underwent total sacrectomy and spinopelvic reconstruction for a low-grade malignant peripheral nerve sheath tumour involving the sacrum. One week later, she developed deep wound infection, and the entire spinopelvic reconstruction was removed. At the 36-month followup, the patient had no pain and was able to walk with a walking frame. There was no sign of recurrence or metastasis.

Mediastinal neurothekeoma: a rare tumor

Neurothekeoma, also known as nerve sheath myxoma, is a benign nerve sheath tumor that usually arises in the cutaneous nerves of the head, neck, or upper extremities. Extracutaneous placement is very rare. Mediastinal neurothekeoma has not previously been reported in the English literature. A 30-year-old woman was admitted to our clinic with back pain. A smooth-edged mass found in her paravertebral region, and a neurogenic tumor was suspected. The tumor was completely excised. Final pathology revealed it to be a mediastinal neurothekeoma.

Soft tissue perineurioma with peripheral lymphoid cuff of the tongue: a case report and literature review

Perineurioma are rare tumors, derived from nerve sheath perineurial cells. Soft tissue perineurioma are extraordinarily rare in the tongue, with only one previous report in a child to our knowledge. Herein, we describe the first case of an adult patient who had a soft tissue perineurioma localized to the tongue, with emphasis on the clinic pathologic and immunohistochemical features of this tumor, and review the previously reported soft tissue cases. Besides, we first describe the histologic feature of peripheral lymphoid cuff in perineurioma.

Ileal perineurioma as a cause of intussusception

CONTEXT

Perineuriomas are rare tumors composed of cells resembling those of the normal perineurium. It usually occurs in subcutaneous, soft-tissue or intraneural locations. Very few reports in the literature have described perineuriomas in the gastrointestinal tract, including the stomach, colon and jejunum.

CASE REPORT

We report the clinicopathological and immunohistochemical features of a case of ileal perineurioma that was manifested clinically as intestinal obstruction due to intussusception. Ileal perineurioma has not previously been reported at this anatomical location.