A statistically significant difference was observed between survival rate of patients having GISTs with MVD of 6 vessels (mean = 2.4, CI 95%: 1.67 – 3.17) and patients having GISTs with MVD of 6 vessels (mean = 2.4, CI 95%: 1.67 – 3.17), P = 0.001. CI 95%: 1.67 – 3.17) and patients having GISTs with MVD of 6 vessels (mean = 2.4, CI 95%: 1.67 – 3.17), P = 0.001. No association for MVD was observed related to sex, age, histological type, risk category, location and metastasis. == Conclusions == Seventy nine cases of GISTs diagnosed at a single center in South Brazil were analyzed for MVD (Chalkley method). There was a statistically significant difference between MVD and the survival rate for these patients. The use of Chalkley method in GISTs may be helpful to evaluate clinical end result. Keywords:GISTs, Angiogenesis, Microvessel density, Chalkley method == Introduction == Gastrointestinal stromal tumors (GISTs) are the most common stromal tumors of the gastrointestinal tract, with an Oxprenolol HCl annual incidence of nearly 2/100,000/12 months [1-4]. They affect males and females similarly and most patients are between 50 and 60 years of age [1-5]. GISTs symbolize 2% of all gastric tumors, 14% of small intestine tumors and 0.5% of colonic tumors [5]. They are thought to arise from interstitial cell of Cajal, a pacemaker cell found in the myoenteric plexus [6-7]. Macroscopically, GISTs are non-encapsulated, well-defined, intra-abdominal nodular lesions, which can cause a bulging in the lumen of the gastrointestinal tract [3-8]. Oxprenolol HCl On histology, about 70% of GISTs are composed of spindle-cells, while epithelioid cells comprise a further 20% and remaining 10% of tumors are of mixed cell types [2,8-11]. The tyrosine kinase receptor, CD117, is present in 90% to 95% of GISTs, usually with diffuse cytoplasmic expression [12-16]. The protein is considered the main diagnostic marker for GISTs, along with CD34, a hematopoietic stem cell marker, present in up to 70% of GISTs [5,17-20]. Some authors, notable Fletcher et al have reported that lesion size and mitotic count can be important predictors of GISTs potential malignancy [10,11,13,14,17,21,22]. These characteristics are used to classify tumors into different risk groups for aggressive behavior [3,10,11,17,22]. Angiogenesis, formation of new blood vessels, Rabbit Polyclonal to CLIP1 plays a central role in cancer survival, local tumor growth and development of distant metastasis [23-25]. Tumor blood supply is usually directly related to an imbalance between pro-angiogenic and anti-angiogenic factors [26-27]. The mainstay of the assessment of tumor vascularity has been counting the number of immunohistochemical recognized microvessels in vascular warm spots [27]. Microvessel density (MVD) has been studied as a prognostic marker in different kinds of human malignancy [24,28-30]. Techniques including Chalkley counting, vascular grade and the use of image analysis systems are explained to evaluate angiogenesis [27], Dornelles et al measured angiogenesis using a method combining MVD, Chalkley grid and image analysis systems [31]. == Materials and Methods == Seventy-nine cases of GISTs diagnosed at the Department of Pathology of Hospital de Clinicas de Porto Alegre from January 1993 to December 2009 were submitted to immunohistochemistral analysis for CD31, (1:10 by DAKO), an endothelial marker, for MVD analysis. Procedures were made according to manufacturers instructions. For antigenic recovery we used citrate buffer with pH 6.0 and Oxprenolol HCl microwave oven. Initially, 3 to 5 5 microscopic fields (200 x) showing the highest microvascular density (hot spots) were recognized, with the use of CD31 antibody (Fig. 1). The mean quantity of stained blood vessels was collected through Chalkley count, where a 25-point grid was placed onto a scanned image and all points coincided with the noticeable vessels were counted. Three to five images were used and the imply value was obtained with the number of counted vessels in each image [31]. == Physique 1. == CD31 antibody in GIST (200 x). Clinical information and follow-up were obtained from medical records of Hospital de Clinicas de.