Primary Extraosseous Ewing Sarcoma of the Maxillary Sinus in an Adult-A Rare Case Report.

Ewing sarcoma (ES), which is described as diffuse endothelioma of the bone, is divided into osseous and extraosseous Ewing sarcoma (EES) mostly affecting children and adolescents. It is a rare, aggressive, and poorly differentiated small blue round cell tumor that seldom affects the head and neck regions.Herein, we reported a 46-year-old man presenting with right nasal block, epistaxis, and epiphora from the right eye for one month. The nasal endoscopy revealed a friable mass arising from the anterior half of the right nasal cavity. Histological findings were suggestive of Ewing sarcoma. A contrast-enhanced computed tomography (CT) scan of the paranasal sinuses showed a soft tissue mass in the right anterior nasal cavity with mucosal thickening in the right maxillary sinus, without any bony erosion or distant metastasis. The patient underwent endoscopic medial maxillectomy with modified Denker's procedure, followed by a 6-cycle course of chemotherapy. He was clinically well after chemotherapy; however, the recent bone scans were suggestive of bone involvement with the tumor.The EES of paranasal sinus in the head and neck regions is extremely rare and requires exceptional attention due to their adjacent vital structures. The ES diagnosis-related dilemma arises from the numerous differential diagnoses of small round blue cell tumors. In this regard, accurate diagnosis is important, since ES requires a multi-modality approach. Furthermore, early diagnosis and aggressive intervention are crucial to obtain good prognosis and function.