Summary Inflammatory pseudotumor of the maxillary sinus:

We report a case of inflammatory pseudotumor in the maxillary sinus of the left side. Inflammatory pseudotumor in the paranasal sinus is very rare. It is difficult to make a diagnosis of inflammatory pseudotumor without a histopathological diagnosis, because it simulates malignant disease clinically. A 65-year-old man was admitted to our hospital because of headache and swelling of the left cheek. CT and MRI findings showed complete occupation of the left maxillary with a large soft tissue mass. There was erosion of the maxillary bony wall and inferior orbital wall with the mass extending from the left maxillary sinus into the left orbit and the pterygopalatine fossa. A FDG-PET revealed that administered FDG was accumulated on the left maxillary sinus. We suspected a malignant tumor of the left maxillary sinus and performed open biopsy under general anesthesia. However, no tumor cells were found in the biopsy specimen, and the histopathological diagnosis was inflammatory pseudotumor. Therefore, we perfomed partial resection of the left maxillary sinus. He was administered prednisolone for 2 months. There has been no regrowth of the mass. The combination of surgery and steroid therapy was effective for inflammatory pseudotumor in the maxillary sinus.