Tic leiomyosarcoma, which transdifferentiated from pancreatic stromal tumor, with liver and peritoneal metastases. Leiomyosarcoma and its subtype, major pancreatic leiomyosarcoma, have seldom been reported. The estimated worldwide incidence of PLMS is 1-2/100,000 population [3]. Baylor et al. identified only 5 circumstances of principal pancreatic leiomyosarcoma in a study of 5057 sufferers with pancreatic cancer [4]. In 1951, Ross et al. reported the initial case of principal pancreatic leiomyosarcoma [5]; because then, only 71 such instances are on record [3]. The gastrointestinal stromal tumor largely arises from Cajal or its precursor cells [6, 7]. Histological and immunogenic properties of extra-gastrointestinal stromal tumors are related to these of gastrointestinalFig.867065-85-8 Order 1 Histopathological (a) and immunohistochemical examination from the 1st biopsy specimen (b, c, d, e) showing Vimentin (+), DOG-1 (+), CD117 (+), SMA (-), respectivelyLin et al.Buy3-Oxoisoindoline-5-carbaldehyde BMC Cancer (2016) 16:Web page 3 ofFig. 2 Histopathological and immunohistochemical examination of liver biopsy specimen (a-c) and surgically resected peritoneal deposits (d-f) showing spindle cells with nuclear mitoses, CD117 (-), SMA (+) respectivelystromal tumor, however the former originates from abdominal or retroperitoneal soft tissues [1].PMID:27108903 For the greatest of our know-how, this can be the first report of a case of extragastrointestinal stromal tumor which progressed to primary pancreatic leiomyosarcoma. The clinical manifestations are non-specific [8]. Our patient was asymptomatic prior to the diagnosis. The radiological examination for main pancreatic leiomyosarcoma has low specificity [2]. Endoscopic ultrasonography-guided biopsy does facilitate a preoperative diagnosis; however, repeated sampling may well be needed [6, 7]. Histological and immunohistochemical examination is the gold common for diagnosis. Inside a study of 12 sufferers with major pancreatic leiomyosarcoma, presence of more than 10/50 nuclear mitotic figures per high power field was connected with poor survival [9]. Xu et al. reported a median survival price of 48 months; survival prices at 1, 3, five and 10 year have been 66.6, 51.two, 43.9 and 29.three , respectively [3]. Non-radical surgery and infiltration of surrounding organ and vessels were independently related with poor prognosis. Yet another study demonstrated the presence of spindle shaped smooth muscle-like cells in principal pancreatic leiomyosarcoma,and IHC markers SMA (+), MSA (+), Desmin (+), CD117 (-), HMB45 (-), DOG-1 (-), CD34 (-) [10], although gastrointestinal stromal tumors were characterized by CD117 (+), CD34 (+), DOG-1 (+), SMA (-), Desmin (-), S-100 (-) [11]. Good staining for CD117 may perhaps assistance differentiate among key amongst extra-gastrointestinal stromal tumors and primary pancreatic leiomyosarcoma. In our study, initial immunohistochemical study of liver and pancreas specimens showed CD117 (+), even though that of liver biopsy and peritoneal specimens at second- surgery detected CD117 (-) and SMA(+), that is indicative of transformation of extra-gastrointestinal stromal tumors to key pancreatic leiomyosarcoma. Imatinib has been reported to induce differentiation of gastrointestinal stromal tumors into leimyoscarcoma [11], which might have contributed to the transdifferentiation observed in our patient.Conclusion Surgery would be the first line therapy for main pancreatic leiomyosarcoma and extra-gastrointestinal stromal tumors. Radical resection either alone or in combinationLin et al. BMC Cancer.