Background: Inflammatory myofibroblastic tumor is an infrequent lesion that is seen in the lungs, abdomen, skin, soft tissue, genital system, and mediastinum. It is rare in the oral cavity. Case presentation: A 58-year-old woman presented with a mass in the left buccal mucosa. An extensive surgical intervention was performed. On gross examination, the mass was 9.5 x 8 x 3.5 cm in size. Microscopically, the tumor included spindle-shaped myofibroblast-like cells intermingling chronic inflammatory cells. Differential diagnosis of inflammatory myofibroblastic tumor is extensive and includes benign and malignant spindle cell tumors, such as cranial fasciitis, solitary fibrous tumor, fibrosarcoma, and rhabdomyosarcoma. Conclusion: Inflammatory myofibroblastic tumors are classified as tumors of intermediate biological potential due to a tendency of local recurrence and low risk of distance metastasis. We found it appropriate to submit this case because of its rarity and rapid growth; also, it is the largest size oral cavity location inflammatory myofibroblastic tumor that has been reported so far.

Keywords: Inflammatory myofibroblastic tumor, inflammatory pseudotumor, oral cavity, ALK-1, case report