Oral inflammatory myofibroblastic tumor demonstrating ALK, p53, MDM2, CDK4, pRb, and Ki-67 immunoreactivity in an elderly patient

Inflammatory myofibroblastic tumor (IMT) is a controversial lesion composed of myofibroblasts, accompanied by varying numbers of inflammatory cells. Various pathogenetic factors have been proposed (ie, reactive, infectious, autoimmune, and neoplastic) but the etiology of most IMTs remains unknown. Here we review the literature of oral IMTs, detailing the demographic profile of these rare lesions. Moreover, we present an unusual case of IMT arising from the mandibular alveolar mucosa of an 82-year-old female. Microscopic examination revealed plump spindle cells set in a myxoid vascular stroma admixed with inflammatory cells. Numerous large ganglion cell-like cells were seen, some exhibiting emperipolesis of neutrophils. Ultrastructurally, prominent myofibroblasts with abundant rough endoplasmic reticulum were noted. Tumor cells were immunoreactive for vimentin, smooth muscle actin, and KP1 (CD68), and negative for desmin, S-100, and EBV-LMP. The lesion was excised without margins and the patient has manifested no evidence of disease at an 18-month recall. In an attempt to further delineate the potential neoplastic nature of this lesion, we assessed the immunohistochemical expression of various markers that have been linked to neoplastic transformation. The recorded positivity for ALK, p53, MDM2, CDK4, pRb, and Ki-67, despite the absence of bcl-2 reactivity, strongly favors the neoplastic origin of the studied tumor.