Malignant peripheral nerve sheath tumors (MPNSTs), formerly known as malignant schwannomas, are rare and highly aggressive neoplasms. They are characterized by the highest local recurrence rate among soft tissue sarcomas, as well as a significant propensity for surrounding tissue infiltration and distant metastasis. MPNSTs account for approximately 5% of all sarcomas and most commonly involve the extremities and trunk. To date, only a few cases of MPNST involving the nasal cavity, paranasal sinuses, or anterior skull base have been reported. The clinical presentation of sinonasal MPNST includes non-specific symptoms, such as nasal obstruction and rhinorrhea, which may persist for years before the tumor is detected. Magnetic resonance imaging (MRI) is considered the gold standard for evaluating tumor size and the extent of tumor invasion. The diagnosis of MPNST is based on histopathological examination supported by immunohistochemical analysis; S-100 protein is the most commonly used marker and is detected in approximately 50–90% of cases. The role of biopsy in the diagnosis of these tumors remains controversial due to their heterogeneity and the risk of underestimating the malignancy grade in limited tissue samples. In clinical practice, although biopsy may be performed, the definitive diagnosis is often established based on evaluation of the entire surgical specimen. The primary treatment for MPNST is radical surgical resection. In cases of incomplete resection, reoperation and/or adjuvant radiotherapy and/or chemotherapy should be considered. Recent advances in understanding the biology of these tumors may lead to the development of novel therapeutic options. However, it is important to emphasize that the initial diagnosis relies on thorough clinical history and otorhinolaryngological examination; thus, high clinical suspicion is crucial given the non-specific nature of early symptoms. The aim of this study is to discuss a rare case of MPNST located within the nasal cavity and paranasal sinuses.