S141 Am J Clin Pathol 2018;149:S140-S149 DOI: 10.1093/AJCP/AQX127 © American Society for Clinical Pathology AJCP / Meeting AbstrActs neoplasms. As such, we compared patients with myeloid disorders who underwent next-generation sequencing (NGS) to compare the percentage of ring sideroblasts and clinical features when SF3B1 variants were detected. We identifed 13 patients with SF3B1 variants; 10 ran- domly selected patients with myeloid neoplasms lacking SF3B1 mutations were used as controls. SF3B1 variants were identifed using a 25-gene panel and interrogated via the Ion Torrent, while ring sideroblasts were quan- titated using the aspirate. Age, sex, disease classifcation, SF3B1 variant type, ring sideroblast percentage, and pro- gression to acute leukemia were recorded for each sub- ject. Among 13 patients with variant SF3B1, the mean age was 73.5 years, 62% were women, and 92.3% were still alive at the time of study. The majority (84.6%) had variants in known SF3B1 “hotspots.” Of these 13 patients, nine (69.2%) met World Health Organization criteria for a recognized myeloid neoplasm with ring sid- eroblasts. Compared to controls, the mean percentage of ring sideroblasts was signifcantly higher in patients with any SF3B1 variant (31.2% vs 2.7%; P = .0011). Among patients with SF3B1 variants in known hotspots, there was a trend toward higher ring sideroblasts (mean 34.8%) as compared to non-hotspot variants (mean 11.5%), although numbers were too small for statistical com- parisons. Subjects with any SF3B1variant and myeloid neoplasm with ring sideroblasts had a lower incidence of high-grade MDS and progression to acute leukemia compared with controls. In summary, SF3B1 variants correlated with an increased number of ring sideroblasts independent of diagnosis. Given their unique attributes, SF3B1-hostspot-positive myeloid neoplasms, particu- larly those associated with MDS, may ultimately be best characterized as a distinctive entity. 327 Evaluation of the Role of pAKT Expression in Epithelial Mesenchymal Transition in Uterine Carcinosarcoma Amir Momeni Boroujeni, MD, Elham Yousef, MD, Ning Chen, MD, PhD, Raavi Gupta, MD; SUNY Downstate Medical Center, Brooklyn, NY Objectives: Epithelial-mesenchymal transition (EMT) has been shown to be the underlying mechanism of the mor- phologic variation of carcinosarcomas. EMT involves loosening of epithelial adhesion structures and trans- formation of epithelial cells into mesenchymal cells. It is believed that EMT in uterine carcinosarcomas (UCSs) is due to alterations of the AKT-pathway. Increased AKT expression leads to modulation of expression of down- stream genes, such as SLUG, leading to cytoskeletal and cell-cell adhesion changes. Loss of E-cadherin expression is the hallmark of EMT. In this study, we investigated the role of AKT in EMT of UCS. Methods: A total of 33 cases of UCS were selected, and survival data were obtained. Immunohistochemical stain- ing with E-cadherin (EP700Y, 1:200 dilution, Roche- Ventana) and pAKT (ab8805, 1:350 dilution, Abcam) was performed. Expression pattern of the antibodies was assessed in the epithelial and mesenchymal components of the tumor. Loss of E-cadherin in the mesenchymal com- ponent was considered epithelial mesenchymal transition. Staining of <20% cells was considered negative. Survival data were compared using cox regression to determine the prognostic signifcance of AKT expression. Results: Of 33 cases, 28 showed loss of E-cadherin expression in mesenchymal component. Fourteen of 28 cases (50%) showed increased expression of pAKT in the mesenchymal component. Three of 28 cases (10.7%) showed positivity of both components, and in 10/28 cases (35.7%), both components were negative for pAKT. One case showed positive pAKT staining in the epithelial com- ponent and negative staining in the mesenchymal com- ponent. Survival analysis showed no prognostic effect of AKT expression. Conclusion: AKT pathway is the main mechanism of epi- thelial mesenchymal transition in UCS. Our results show that AKT pathway alterations drive the EMT in 50% of UCS cases. In other cases, alternative pathways such as RHOA/ROCK pathway should be investigated. The mechanism of EMT appears to have no effect on survival. 328 EBV and HHV1 Positive CNS Infammatory Pseudotumor: A Case Report Christian Salib, MD, Taliya Farooq, MD, George Kleinman, MD; Westchester Medical Center/New York Medical College, Valhalla Infammatory pseudotumor (IPT) is a rare benign lesion of unknown cause, commonly involving the lung and orbit but found in virtually every body site. IPT was frst described in 1954 based on imaging fndings that mim- icked those of malignant tumors. This rare entity, which consists of mixed infammatory cells and myofbroblas- tic spindle cells, is often associated with Epstein-Barr virus (EBV) positivity. Here we are presenting a case of a 56-year-old Hispanic woman with a history of headaches, dizziness, and frequent falls. MRI of the head demon- strated a right temporal lesion with enhancement along the temporal convexity, extending into the insula. A lum- bar puncture yielded atypical lymphocytes with increased nuclear to cytoplasmic ratio, irregular nuclear contours, and coarse chromatin. Cerebral spinal fuid fow cytome- try revealed a mixed population of cells, including B-cells expressing CD19, CD20, kappa, and lambda. A subse- quent open biopsy revealed areas of dense, mixed infl- trates consisting of lymphocytes, histiocytes, plasma cells Downloaded from https://academic.oup.com/ajcp/article/149/suppl_1/S141/4801619 by guest on 18 December 2021