CASE REPORT
Ethical approval for this case report was obtained from the institutional review board of the Tokai University Hospital (approval number 21R-269). The study was conducted in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki). The institutional review board was responsible for anonymizing the patients, and the requirement for informed consent was waived.
A 51-year-old man visited our clinic with the chief complaint of right cheek pain. The right middle meatus was edematous and closed, and bloody rhinorrhea was observed (Fig. 1). The Papanicolaou classification of nasal cytology was Class Ⅲ (Cytology suggestive of, but not conclusive for, malignancy) and CT revealed a right maxillary sinus shadow with a partial bony defect, suggesting a malignant disease (Fig. 2ab). However, MRI revealed an internally homogeneous lesion without contrast effect. It exhibited low signal intensity on T1 and T2, and no invasion outside the maxillary sinus, thus suggesting an inflammatory disease (Fig. 2cd). Endoscopic right sinus surgery was performed under local anesthesia to improve the right buccal pain via decompression and to confirm the diagnosis. The right maxillary sinus contained a highly viscous mucus reservoir and a large amount of yellowish-white debris. Allergic fungal rhinosinusitis was suspected (Fig. 3ab). The histopathological diagnosis was diffuse large B-cell lymphoma, based on the mucous accumulation and debris from the sinus and its mucosa (Fig. 3cd). The patient underwent radiochemotherapy, attaining disease remission.