Inflammatory myofibroblastic tumor

Abstract

Inflammatory myofibroblastic tumor is an uncommon lesion of unknown cause. It encompasses a spectrum of myofibroblastic proliferation along with varying amount of inflammatory infiltrate. A number of terms have been applied to the lesion, namely, inflammatory pseudotumor, fibrous xanthoma, plasma cell granuloma, pseudosarcoma, lymphoid hamartoma, myxoid hamartoma, inflammatory myofibrohistiocytic proliferation, benign myofibroblatoma, and most recently, inflammatory myofibroblastic tumor. The diverse nomenclature is mostly descriptive and reflects the uncertainty regarding true biologic nature of these lesions. Recently, the concept of this lesion being reactive has been challenged based on the clinical demonstration of recurrences and metastasis and cytogenetic evidence of acquired clonal chromosomal abnormalities. We hereby report a case of inflammatory pseudotumor and review its inflammatory versus neoplastic behavior.

Keywords: ALK-1; myofibroblasts; neoplastic; reactive.

Figure 1

Pre-operative photograph showing diffuse extraoral swelling

Figure 2

(a) Spindle cell proliferation (×100); (b) infl ammatory cells forming germinal centers (×100)

Figure 3

(a) Focal ALK-1 positivity seen in spindle cells (×100); (b) SMA positivity seen in spindle cells (×100); (c) vimentin positivity in spindle cells (×100); (d) vimentin positivity seen in spindle cells (×400)

Figure 4

Postoperative photograph