title: Inflammatory myofibroblastic tumor withRANBP2andALKgene rearrangement with bland cytological features mimicking desmoid-type fibromatosis: A case report and review of the literature.
abstract: Here, we present an uncommon case of inflammatory myofibroblastic tumor (IMT) involving the mesentery. The tumor was composed of loosely arranged round-to-spindle-shaped tumor cells with amphophilic cytoplasm in an inflammatory and myxoid background. The mitotic activity was low (1 per 50 high-power fields) and the tumor cells lacked cellular atypism. Immunohistochemically, the tumor cells demonstrated strong nuclear membranous staining with anaplastic lymphoma kinase (ALK).In situhybridization for ALK gene rearrangement revealed a splitting apart of the two signals within the tumor cells. Reverse transcription-polymerase chain reaction revealed that the tumor harbored a ran-binding protein 2 (RANBP2)-ALK rearrangement. IMTs are usually characterized by epithelioid-to-round cells featuring increased mitotic activity, occasionally demonstrating unusual tumor cells and more aggressive clinical behavior. To date, 23 IMTs have been reported with RANBP2 and ALK gene rearrangements. However, the present case demonstrated indolent cytological features, leading to a difficulty in differentiating it from desmoid-type fibromatosis.
authors.affiliation: Department of Pathology, Chi-Mei Medical Center, Tainan 710, Taiwan, R.O.C.
authors.forename: Yu-Hua
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Department of General Surgery, Chi-Mei Medical Center, Tainan 710, Taiwan, R.O.C.
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Tian
authors.affiliation: Department of Pathology, Chi-Mei Medical Center, Tainan 710, Taiwan, R.O.C.; National Institute of Cancer Research, National Health Research Institutes, Tainan 704, Taiwan, R.O.C.; Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan, R.O.C.; Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan, R.O.C.
authors.forename: Chien-Feng
authors.initials: CF
authors.lastname: Li
keywords: anaplastic lymphoma kinase; inflammatory myofibroblastic tumor; ran-binding protein 2; round cell