PRESENTATION OF A RARE CASE OF LARYNGEAL SCHWANNOMA WITH SHORT LITERATURE REVIEW

Introduction. Laryngeal schwannomas are rare benign neurogenic tumors. They are usually localized in the supraglottic portion of the larynx. Case report. We report a rare case of laryngeal schwannoma with a focus on clinical presentation, diagnosis and management. A 61-year old male patient with a 3-year history of hoarseness underwent telescopic examination which revealed an oval submucosal tumefaction of the left ventricular fold extending over the left vocal fold toward the right ventricular fold. Multi-slice computed tomography showed a 22x15mm well defined, oval heterodense mass in the region of the left ventricular fold, extending toward the left vocal fold and the posterior commissure of the larynx, with signs of initial compression lesion of the thyroid cartilage. Biopsy and histopathology report revealed a primary benign encapsulated mesenchymal tumor, while immunohistochemistry analysis confirmed schwannoma diagnosis. The patient underwent tracheotomy and left hemilaryngectomy, with complete removal of the tumor. There were no signs of recurrence at the six-month follow-up. Conclusion. Schwannomas are rare among benign tumors of the larynx and might grow for years before being diagnosed. Biopsy with histopathology analysis is used to confirm the diagnosis of laryngeal schwannoma, although extreme care should be taken during biopsy. Treatment consists of complete surgical excision, while surgical approach depends on the size and localization of the tumor, as well as on the presence of a peduncle.


Introduction
Schwannoma is a benign slow-growing encapsulated neurogenic tumor, originating from Schwann cells that surround somatic and autonomic peripheral and cranial nerves, except the olfactory and optic nerves which lack Schwann cell sheath 1,5,7 . Between 25% and 45% of all schwannomas are located in the head and neck area, predominantly in the parapharyngeal space 1 . The only known risk factors for schwannoma occurrence are genetics and exposure to radiation 2 . Laryngeal schwannomas are extremely rare and account for 0,1%-1,5% of all benign laryngeal tumors 3 .
We present a rare case of laryngeal schwannoma in a 61-year-old male patient.

Case report
A 61-year-old male was admitted to our clinic due to hoarseness over the past three years, which had been gradually worsening. He is a nonsmoker and consumes alcohol

Discussion
Laryngeal schwannomas are most common in females in the fourth and fifth decade of life, although they can occur at any age 4 . Contrary, our patient was a male in his seventh decade. Most commonly, the nerve of origin is the inner branch of the superior laryngeal nerve or small nerve fibers that innervate laryngeal submucosa. In 80% of cases, laryngeal schwannomas are located at the aryepiglottic fold, while 20% occur at the vocal or ventricular fold, as in our case 5 .
Clinical manifestations of laryngeal schwannomas depend on its size and localization. The most common symptoms include hoarseness (71,2%), dysphagia (24,6%), dyspnea (23,3%) and globus sensation (16,4%) 6 . Acute respiratory failure might occur, mainly in large pedunculated tumors, which can cause complete airway obstruction 7 . A case of asphyxial death caused by laryngeal schwannoma has also been described 8 . Our patient complained of hoarseness for the past three years that had been gradually worsening. Typically, laryngeal schwannomas do not cause symptoms such as palpable cervical mass and weight loss 1 , which were not present in our case either. There is only one described case of laryngeal schwannoma presenting as a painless neck mass 9 .
Differential diagnoses of schwannoma include laryngeal cyst, laryngoceles, mucoceles, chondromas, adenomas, lipomas and neurofibromas. It is important to differentiate schwannoma from neurofibroma, because the latter have a higher incidence of malignant transformation (around 10% of cases) and a higher recurrence rate 1 . Presence of neurofibroma could also indicate possible neurofibromatosis 5 .
Diagnosis of laryngeal schwannoma is based on anamnesis, direct or indirect laryngoscopy, imaging methods such as computed tomography and/or magnetic resonance imaging and biopsy with HP analysis 1 . Ultrasonography of the larynx is rarely used, due to difficulties in visualizing posterior structures of the tumor and the larynx. As in our case, computed tomography and magnetic resonance imaging show typical characteristics of a benign lesion: circular or oval mass with well-defined borders, mostly isodense compared to muscle and compressing without infiltrating surrounding tissue 6 . The gold standard in diagnosing schwannoma is HP analysis 5  There is still no consensus on how long the patient should be monitored after the treatment. Tulli et al. report that the follow-up differs widely, from 2 months to 17 years, with laryngeal schwannoma recurrence usually being observed within 3 months after tumor excision. Therefore, controls are recommended every 3 months during the first year after excision, and then at least once a year for the next two years 6 . We did not notice any signs of recurrence six months after surgery. We advised the patient to check in regularly, at least once a year.

Conclusion
Laryngeal schwannomas are very rare and can be overlooked for years due to their mild clinical manifestations. The gold diagnostic standard is histopathology analysis.