A Case of Sinonasal Low-Grade Nonintestinal Adenocarcinoma That Was Difficult to Diagnose Preoperatively

Abstract

We report a case of sinonasal low-grade, nonintestinal adenocarcinoma (LG non-ITAC). The patient, a 56-year-old woman, was referred to our university hospital for a left nasal tumor with nasal obstruction, epistaxis, and nasal discharge. Nasal endoscopy revealed a nasal polypoid tumor with a smooth margin occupying the left nasal cavity. The sinonasal tumor was diagnosed as an exophytic papilloma by histopathology. Sinonasal contrast computed tomography (CT) confirmed homogeneous opacification of the left frontal, maxillary, and ethmoidal sinuses. There was no evidence of a potential bone defect. T2-weighted magnetic resonance imaging (MRI) showed a relatively uniform high signal intensity area in the left maxillary and frontal sinuses. An area of high signal intensity was also found in a part of the left ethmoid sinus. Left transnasal endoscopic ethmoidectomy was performed under general anesthesia. The tumor in the nasal cavity was prone to bleeding. We defined the site of tumor attachment as the suprabullar cell. The anterior ethmoidal artery was exposed, and the tumor was carefully dissected and removed. Based on the findings of these radiological and histological examinations, the sinonasal tumor was diagnosed as a LG non-ITAC. Sinonasal non-ITAC is an adenocarcinoma without the histopathological characteristics of salivary or intestinal-type adenocarcinoma. Non-ITAC is additionally classified into the high-grade and LG types. LG non-ITAC is very uncommon. Thus far, there is only one published report in the literature on the clinical and therapeutic characteristics of LG non-ITAC in Japan. Non-ITAC has a good prognosis, with a low risk of metastasis. Therefore, it is imperative to suspect and distinguish non-ITAC from other sinonasal tumors with similar symptoms preoperatively.