Inflammatory myofibroblastic tumor of the maxillary sinus related with pulp necrosis of maxillary teeth: case report.

Inflammatory myofibroblastic tumor (IMT) is a benign lesion composed of myofibroblasts accompanied by varying numbers of inflammatory cells. Various pathogenetic factors have been proposed, but the etiology of most IMTs remains unknown. This article presents a case of IMT occurring in the left maxillary sinus. A 24-year-old man complained of throbbing pain in the maxillary left molars and swelling of the left cheek. His maxillary left second molar was diagnosed as pulp necrosis and root canal treatment performed. After that, his symptoms continued and he was referred to the Department of Otolaryngology. Computerized tomography disclosed compact soft tissue masses in the left maxillary sinus with obstruction of maxillary ostium. Under general anesthesia, the lesions were fully excised. Histopathologically, the lesions were composed of plump or spindled myofibroblasts. Cells were immunoreactive for smooth muscle actin and β-catenin, and were negative for ALK1, CD34, and EMA. The diagnosis was IMT of left maxillary sinus. Although it is very rare, IMT should be included as a differential diagnosis in patients with compact masses in maxillary sinus.