Concurrent Monoclonal Gammopathy of Undetermined Significance in a Patient With Maxillary Sinus Fungus Ball.

Fungus ball is a common disease encountered in rhinology departments. As it usually affects immunocompetent patients, other systemic diseases occurring concurrently with fungus ball have not been reported often. Recently, we encountered a patient who was diagnosed with fungus ball in the maxillary sinus and underwent endoscopic sinus surgery. During the surgery, fungus ball-like materials were sucked out and a maxillary sinus mucosal biopsy was performed. The post-operative pathologic report demonstrated that there were many plasma cells; the patient underwent several additional tests in our hematologic department. Finally, he was diagnosed with monoclonal gammopathy of undetermined significance (MGUS). In the present report, we summarize our experience with this patient and share the lessons that we have learned from this case.