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Introduction/Objective Inflammatory myofibroblastic tumor (IMT) is an uncommon spindle cell lesion that can involve various organs and occurs in multiple body sites. While older terminology (i.e. inflammatory pseudotumor) suggested otherwise, recent molecular studies point toward a neoplastic pathogenesis for IMTs. Herein, we report a case of an abdominal IMT and discuss the morphologic and immunohistochemical pitfalls pertaining to this entity. Methods A 75-year-old woman presented with complaints of generalized abdominal pain and distention. An abdominal CT scan showed multiple peritoneal masses, the largest of which measured 23 cm. Biopsy revealed compact fascicles of bland spindle cells exhibiting diffuse actin and caldesmon immunoreactivity, consistent with a spindle cell tumor with smooth muscle differentiation. Mitotic activity was low-to-unapparent. Surgical excision was performed. The cut surface of the tumor was tan-white with hemorrhagic foci. Histopathologic examination of the tumor showed elongated spindle cells set in a loose myxoid stroma rich in blood vessels and a mixed inflammatory infiltrate. Deeper sections of the tumor were more cellular, showing a similar morphology to that seen in the original biopsy, which was virtually devoid of inflammatory cells. Immunohistochemistry showed diffuse staining for desmin, caldesmon, smooth muscle actin, and ALK. FISH analysis showed ALK gene rearrangement in 52% of tumor cells, confirming the diagnosis of IMT. Results Studies in the literature show that IMTs express smooth muscle markers such as SMA (90%) and desmin (50%). However, immunoreactivity for caldesmon is rarely reported. ALK immunoreactivity is seen in about 35–60% of cases, and when gene rearrangement involving ALK is detected the diagnosis can be confirmed. Conclusion Historically, several terms have been used to describe IMTs, including inflammatory pseudotumor and inflammatory pseudosarcomatous fibromyxoid tumor. While the nomenclature consistently implies an inflammatory infiltrate, this tumor could have various morphological patterns with some areas showing very little to absent inflammation, as demonstrated in our case. Hence, making an accurate diagnosis could be challenging on a limited biopsy. Therefore, ALK testing should be included as part of the diagnostic workup of spindle cell neoplasms with smooth muscle differentiation.

Inflammatory myofibroblastic tumor (IMT), a rare sarcoma, is primarily treated via resection of the mass. However, there is no standard treatment for recurrence or unresectable tumors. Almost 50% of IMTs carry ALK gene rearrangement that can be treated using ALK inhibitors, but therapeutic options for ALK-negative tumors are limited. This report describes a woman aged 22 years with unresectable ALK-negative IMT. Next-generation sequencing revealed a TFG-ROS1 fusion, and she had a partial response to the ROS1 inhibitor ceritinib. This report provides the first published demonstration of a patient with IMT with ROS1 fusion successfully treated using ceritinib. Our study suggests that targeting ROS1 fusions using the small molecule inhibitor shows promise as an effective therapy in patients with IMT carrying this genetic alteration, but this requires further investigation in large clinical trials.

Introduction: Paraneoplastic pemphigus is an autoimmune disease associated with an underlying tumor. Several cases have been reported as unusual pemphigus vulgaris, erythema multiforme, or paraneoplastic bullous disease,1 but the incidence of the condition is unknown.2 Response to treatment is generally poor, with significant morbidity and mortality. This condition is clinically characterized by severe mucositis and polymorphic blistering skin eruptions, and histologically by acantholysis, keratinocyte necrosis, and interface dermatitis.3 Immunoprecipitation and immunoblot testing detect autoantibodies against desmosomal polypeptides.4 We describe a case of paraneoplastic pemphigus associated with an abdominal inflammatory myofibroblastic tumor in a 7-year-old girl.

An inflammatory myofibroblastic tumor, also known as inflammatory pseudotumor, is a rare neoplasm characterized by myofibroblastic spindle and inflammatory cells that cause masses in many sites of body. It is often benign, but in some cases neoplastic transformation has been reported as a result of aggressive growing. In our case, an inflammatory myofibroblastic tumor was reported by biopsy of a 25 × 15 cm abdominal mass. How to cite this article Tastekin F, Ersoy M, Temel T, Ozgenel SM, Canaz F, Özakyol A. Abdominal Inflammatory Myofibroblastic Tumor: A Rare Case. Euroasian J Hepato-Gastroenterol 2016;6(2):183-185.

Background and Purpose Inflammatory myofibroblastic tumor (IMT) is a proliferative lesion of controversial nosology and uncertain prognosis. In an attempt to acquire further understanding of pathogenesis and biologic behavior, we surveyed abdominal IMTs managed over the last 12 years at a single institution. Methods Intra-abdominal IMTs treated between 1995 and 2007 were reviewed concerning demographic, clinical, and pathologic features as well as therapeutic management and outcome. All specimens were reevaluated by histologic examination and immunohistochemistry. Results There were 7 patients (4 males; age range, 28 days to 14 years). Five lesions were located in alimentary tract: 1 gastric presenting with bleeding, 1 hepatic presenting with a thoracic wall mass, 1 pancreatic and 2 colonic presenting with obstructive symptoms. One splenic IMT was found incidentally. The remaining case arose from the adrenal gland and presented with a palpable mass. The gastric and adrenal IMTs had evidence of a previous or concomitant infectious setting. Five lesions were excised. The pancreatic IMT underwent a drainage procedure followed by steroid administration, and the hepatic lesion received antibiotics. Histopathology revealed characteristic findings of IMT. Expression of anaplastic lymphoma kinase was negative in all cases. At a median follow-up of 6 years (range, 3-15), all children were asymptomatic with no recurrences. The hepatic and pancreatic IMT displayed complete and near total regression, respectively. Conclusion A benign behavior of abdominal IMTs was observed even in patients not undergoing surgical excision. Although IMT remains a surgical disease, a conservative approach may be reasonable in select cases.

症例は61歳，男性．腹部CTで上行結腸を外側より圧排する境界明瞭，分葉状の6cm大充実性腫瘍を認めた．病理組織学的診断は炎症性筋線維芽細胞性腫瘍（Inflammatory myofibroblastic tumor;IMT）で，密な膠原線維の間に筋線維芽細胞様紡錘型細胞と大型の胞状核を有する神経節細胞様細胞が存在し，慢性炎症細胞の浸潤を伴っていた．12年前に回盲部合併切除術を施行したIMTの再発であり，後腹膜剥離面での腫瘍の遺残が原因と考えられた．免疫組織化学ではactin-SM陽性，ALK-1は陰性であった．IMTは従来，炎症性偽腫瘍と総称されていたが，明らかに腫瘍的性質を示す良悪性中間型の腫瘍として新たに位置付けられた疾患単位である．今回，再発をきたしたIMTの切除例を経験したので，若干の文献的考察を加えて報告する．

A 9-year-old girl presented with lethargy, malaise & chest pain. Her blood counts confirmed hypochromic microcytic anemia. She was prescribed iron supplements. Subsequently she was admitted to our hospital with fever and increasing chest and abdominal pain. She was treated with antibiotics, and a diagnosis of "early chest infection" was made. Over the following 2 weeks she failed to improve, and her anemia worsened. She was readmitted, and found to have a mass in her lower abdomen with pressure symptoms on her bowel and bladder. A white-cell scan showed increased uptake in right lower quadrant. An ultrasound and a CT scan confirmed a mass adjacent to her bladder. Needle biopsy showed it to be an unusual localization of an inflammatory myofibroblastic tumor (IMT) of cecum. A presentation with chest pain, fever, anemia and pressure symptoms was highly unusual of a lower abdominal IMT mass. She had a successful excision of the tumor, with resolution of her symptoms.

Inflammatory myofibroblastic tumors are usually treated by surgical resection. We herein report two cases of intra-abdominal inflammatory myofibroblastic tumors that were unresectable and underwent spontaneous regression without any treatment. Our case report and literature review show that regression is more common in the middle-aged and older male populations. Abdominal discomfort and fever were the most common symptoms, but the majority of patients had no obvious physical signs. There was no specific indicator for diagnosis. The majority of the lesions regressed within 3 mo and nearly all of the masses completely resolved within 1 year. We conclude that the clinical characteristics of inflammatory myofibroblastic tumors are variable and, accordingly, the disease needs to be subdivided and treated on an individual basis. Surgery is always the first-line treatment; however, for those masses assessed as unresectable, conservative therapy with intense follow-up should be considered.

Inflammatory myofibroblastic tumors (IMT) are lesions that mostly affect young adults and children. The tumor is made up of myofibroblasts and a mixed inflammatory infiltrate and rarely undergoes malignant transformation. We present a case of a 13-year-old boy with a pelvic mass diagnosed as IMT which underwent malignant transformation and metastasised to the liver. We report the ultrasound, computed tomography (CT) and magnetic resonance (MR) findings of this rare disorder.