Inflammatory myofibroblastic tumor of the oral cavity

Inflammatory myofibroblastic tumor (IMT) is a rare tumor of unknown etiology and pathogenesis. The lesion has been recognized to occur at various sites but rarely affects the head and neck region. A 29-year-old male presented with a 13 months' history of a slow growing, painless growth in maxillary left posterior gingiva. An excisional biopsy was performed under local anesthesia. Microscopic examination revealed a compact cellular spindle cell proliferation with collagenous stroma having storiform architecture. Immunohistochemistry revealed that the tumor cells were positive for smooth muscle actin, CD-68 and negative for anaplastic lymphoma kinase. Oral IMT should be included in the differential diagnosis of localized gingival enlargement mimicking oral hyperplastic/reactive lesions.