He, Rong

Introduction Patients with inherited and acquired platelet disorders (PD) frequently present with thrombocytopenia and/or mucocutaneous bleeding. Diagnosis of PDs relies on both clinical and laboratory investigation, which encompasses both routine and esoteric platelet testing. The former includes platelet indices, light transmission aggregation (LTA) and platelet function analyzer (PFA-100). The latter includes platelet glycoprotein (GP) assessment by flow cytometry and platelet transmission electron microscopy (PTEM). Several recent studies have demonstrated limited sensitivities of routine platelet testing. It is uncertain if a combination of both routine and esoteric testing can vastly improve the sensitivity. Our goal is to assess the value of platelet esoteric testing and the ultimate sensitivity of laboratory platelet testing in diagnosing PDs. Methods Patients (between year 2012 and 2015) with a known or suspected inherited or acquired platelet disorders were recruited for platelet routine and esoteric testing. Patients' clinical features including ISTH bleeding assessment tool (BAT) scores, platelet count, LTA, PFA-100 ADP (CADP) and epinephrine (CEPI) cartridge closure times, GP expression by flow cytometry and PTEM were performed. All clinical and laboratory variables were collected and statistically analyzed. Results A total of 69 patients (51 females; median age 40 years; range: 8 months to 76 years) were enrolled to this cohort study. By retrospective chart review, 34 patients (49%) had a positive ISTH-BAT score (range 0 to 16). The most common bleeding manifestations (on any degree of severity) were cutaneous bleeding present in 53% of patients (n=37), menorrhagia in 47% of females (n=24), epistaxis in 36% (n=25) and postoperative bleeding in 35% (n=24). Joint, muscle and CNS hemorrhage were the least frequent with 7%, 6% and 1% of patients reporting bleeding in these sites. A total of 22 patients (32%) had thrombocytopenia at the time of their evaluation. Fifty-eight patients (84%) had platelet aggregation studies and of those 15 (26%) had an abnormal study. PFA-100 was performed in 57 patients (83%) of whom 42% (n=24) had prolonged closure times with either ADP or epinephrine. PTEM was performed on all samples. Twenty-seven patients (39%) had abnormal platelet structure including 17 patients who had dense granule deficiency. GP by flow cytometry was performed in 41 patients (59%) and abnormal glycoprotein expression was detected in 6 patients (15%). Of the 55 patients who had all tests performed, 22 patients (40%) had completely normal results. Of the routine tests, only PFA-CEPI or -CADP prolongation is associated with the likelihood of a PTEM abnormality (P<0.005). With the assistance of molecular testing, there were 2 cases of MYH-9 mutation-related platelet disorders, one of RUNX1 mutation-associated thrombocytopenia, one of York platelet syndrome, two of Bernard Soulier variants, one of Quebec syndrome and three of gray platelet syndrome or variants. Bleeding scores showed no statistically significant association with severity of any laboratory abnormalities. Conclusion In this cohort, the sensitivity of routine platelet testing in clinically suspected PDs is about 30-40%. Addition of platelet esoteric testing improves the sensitivity to 60%. However, the degree of platelet laboratory abnormalities do not predict severity of bleeding. The findings of this cohort underscore the importance of clinical assessment and both platelet routine and esoteric testing in investigation of patients with suspected PDs. Disclosures No relevant conflicts of interest to declare.

Abstract Background: CLL patients (pts) treated with novel targeted therapies continue to experience disease progression. Approximately 7-15% of relapsed CLL treated with ibrutinib or venetoclax developed Richter's syndrome (RS), an aggressive high grade lymphoma transformation. Standard chemotherapy has limited efficacy in RS. We hypothesized that checkpoint blockade would re-establish anti-tumor immune response in progressive CLL/RS and here we aim to update the clinical data and correlative analysis of MC1485: a phase 2 study of PD-1 blocking antibody pembrolizumab in relapsed/refractory CLL and RS. Methods: Relapsed/refractory CLL including RS enrolled in the CLL arm of MC1485 trial was reported here. The primary end point of this study is overall response rate (ORR). Pts with prior allogeneic stem cell transplant were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks. NCI CTCAE v4.0 and IWCLL 2008 criteria were used for non-hematological adverse events (AE) and for CLL grade hematological AE. Tumor expression of PD-1 and PD-L1 were assessed with standard immunohistochemical (IHC) staining. Percentage expressions of individual antigens were analyzed with whole-slide scanning followed by image analysis with Image-Pro software (Media Cybernetics). Fluorescence in situ hybridization (FISH) was performed on available CLL/RS tissue sections to assess copy number of chromosome 9p region that contains PD-L1 and PD-L2. Results: 25 pts including 16 CLL and 9 RS (biopsy-proven large cell lymphoma) were enrolled in CLL arm. The median age was 69 years (46-81). Twelve (48%) pts had del(17p) or monosomy 17 or TP53 mutation. The median number of prior therapies was 4 (1-10). 96%, 72% or 48% of pts had received alkylator and anti-CD20 antibody, purine analog or anthracycline. Fifteen (60%) pts had prior ibrutinib and 12 (48%) progressed clinically while receiving ibrutinib, including 6 who progressed to RS and 6 who developed progressive CLL. The median number of pembrolizumab doses that pts received was 3 (1 to 21), administered over a median treatment duration of 11 weeks (1 to 56). Drug-related AE occurred in 21 pts (88%) with the most common ones being neutropenia in 9 (37%), cough in 7 (29%) and dyspnea in 6 (25%) pts. Drug-related grade 3 or above AE occurred in 9 (38%) pts with most common ones being thrombocytopenia (5, 21%), dyspnea (2, 8%), and fatigue (2, 8%). The most common immune-related AE was liver enzyme elevation (12%, 8% G3) and was reversible with therapy interruption or steroid therapy. Based on investigator assessment using the Revised Response Criteria for Lymphomas and IWCLL 2008 criteria, one RS pt had complete response (CR, 4%), 3 RS had partial responses (PR, 12%). Among 9 RS pts, 1 CR (11%), 3 PR (33%), 3 SD (33%) and 2 PD (22%) were observed. Thus the ORR in RS was 44%. No CLL pts achieved a CR/PR, 3 had SD and 9 had progressive disease (PD). The ORR of all pts was 16%. Of the 4 RS who had CR/PR, responses occurred early after 2 cycles of therapy and median duration of therapy for CR/PR pts was 8.3 months with data cut-off by June 30th 2016 (Figure 1A). The causes for therapy discontinuation in RS were PD (3, 33%), alternate therapy (2, 22%), and thrombocytopenia due to increased marrow CLL (1, 11%). Increased marrow CLL was observed in 2 RS pts with PR to RS phase of disease assessed by PET, thus the protocol was amended to allow addition of idelalisib/ibrutinib to control the underlying marrow CLL. For RS pts who had a CR/PR or SD, variable nodal responses were observed (Figure 1B). In particular, 6 RS who had prior ibrutinib experienced CR or PR or SD with nodal responses. After a median follow-up of 10.2 (1.9 to 16.1) months, the median overall survival (OS) for all pts was 10.7 months (95% confidence interval [CI], 5.4 to not reached). The 6 month OS rate for RS and CLL pts were 73% and 59%, respectively. Biomarker assessment using IHC analysis on 10 pts with available tumor/nodal tissues (6 RS and 4 CLL) showed an increased expression of PD-L1 (p = 0.02) and a trend for an increased expression of PD-1 (p = 0.1) in the group of pts with CR/ PR versus pts in the group with no clinical response. One out of 10 tested showed polysomic for chromosome 9p. Conclusion: Pembrolizumab had an acceptable safety profile in CLL and RS patients. We confirmed that pembrolizumab has substantial therapeutic activity in RS. Single-agent pembrolizumab does not appear to have clear activity in CLL. Disclosures Ding: Merck: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding. Shanafelt:GlaxoSmithKline: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract Background: Myelodysplastic syndromes (MDS) are rare hematological neoplasms that are more typically seen in elderly patients. Young patients (< 50 years old) have been reported to comprise between 3-6% in the Surveillance, Epidemiology and End Results (SEER) (Ma X et al, Cancer 2007; Rollison R et al, Blood 2008) with a better overall survival (OS). We hereby report the characteristics of young MDS patients with long survival follow-up. Methods: A total of 1012 MDS patients' data from Oct 1993 to Dec 2015 at Mayo Clinic were reviewed after appropriate IRB approval was obtained. All cases had their bone marrow slides reviewed at our institution. Patients youngers than 50 years old (yMDS) were included as cohort 1, while the rest was included as control group (cohort 2). Prognostic factors were analyzed by univariate and multivariate analyses. Survival estimates were calculated using Kaplan-Meier curves and univariate and multivariate analyses was based on log-rank testing using JMP software version 10. Results: Characteristics: We identified 68 (7%) yMDS patients with a median age of 42 years (range, 18-49). Female gender was more common in yMDS (43% vs 31%, p= 0.05). Upon comparison between cohort 1 and 2, only platelets were significantly lower in yMDS (61 vs 102, p <0.0001), but not white blood cells, hemoglobin or degree of marrow fibrosis. MDS subtyping according to World Health Organization 2016 showed single lineage dysplasia in 15% vs 2%, multilineage dysplasia 24% vs 36% , ring sideroblasts 9% vs 15%, isolated del (5q) 1% vs 3%, excess blasts 44% vs 31%, and unclassifiable in 6% vs 5%. As expected, therapy related MDS (t-MDS) was more frequent in yMDS (33% vs 17%, p= 0.005). Transformation to acute myeloid leukemia (AML) was also more frequent in yMDS (28 % vs 11%, p= 0.0004). Compared to cohort 2, yMDS IPSS-R scores were very high, high, intermediate, low, and very low in 24% vs 13%, 29% vs 16%, 21% vs 20%, 19% vs 35%, and 7% vs 17%, respectively. Allogenic hematopoietic cell transplantation (HCT) was more frequent in yMDS (42% vs 4%, p< 0.0001). Survival outcome: Median OS was longer for cohort 1 vs cohort 2 but did not reach statistical significance (43 vs 21 months, p= 0.1). Median progression free survival (PFS) was shorter for cohort 1 vs cohort 2 but did not reach statistical significance (8 vs 12 months, p= 0.3). Median OS for cohort 1 based on R-IPSS was 44, 105, 40, 18, and 12 months for very low, low, intermediate, high and high risk groups, respectively (p= 0.09). Median OS was shorter in t-MDS vs de novo MDS in cohort 1 (13 vs 47 months, p = 0.04). Young patients who had transformed to AML had a worse median OS (18 vs 93 months, p=0.001). On multivariate analysis neither t-MDS nor R-IPSS had a statistically significant impact on OS. Conclusions: MDS is rarely diagnosed under the age of 50. IPSS-R was less powerful in detecting differences between its risk groups for this patient population, although more than half of the patients with yMDS had either high or very high risk. Among this cohort of yMDS patients, there was a significantly higher proportion with therapy-related myeloid neoplasms compared to older patients (one third of patients), with subsequent higher rates of transformation to AML and higher allogeneic HCT. In our study, we did not find an improved OS for yMDS patients compared to older patients. Disclosures Al-Kali: Celgene: Research Funding; Onconova Therapeutics, Inc.: Research Funding.

Abstract Background: Acute myeloid leukemia (AML) is an aggressive form of blood cancers with a wide range of response and relapse rates using standard chemotherapy regimen (commonly known as 7+3). Several genes (FLT3, IDH1, RAS) have been targeted using small molecule tyrosine kinase inhibitors with encouraging results. The stem cell receptor tyrosine kinase KIT is expressed more than 10% in the blasts in 95% of relapsed AML cases and mediates leukemic proliferation and has anti-apoptotic effects (Domen and Weissman 2000). AML with high KIT expression is associated with poorer outcome (Del Poeta, Venditti et al 2003). Goals: To study the efficacy and safety of combination 7+3 and nilotinib in patients (pts) with AML and KIT expression. Primary goal is to determine the complete response (CR) rate; while secondary goals include 2-year overall survival (OS) and disease free survival (DFS) in addition to safety of DATA regimen. Methods: A single arm, Phase II study, enrolled pts at Mayo Clinic (MN and AZ). Appropriate IRB was obtained and study was registered (NCT 01806571). Pts were enrolled if they were newly diagnosed with AML with KIT (CD117) expression of 20% or higher on myeloblasts by flow cytometry. KIT mutations were allowed if present. Nilotinib 300 mg twice daily was given on days 4-14 of induction and consolidation; and continuous daily maintenance therapy for up to 2 years. Cytarabine 100 mg/m2/day continuous IV x7 days plus daunorubicin 60 mg/m2 IV daily x3 days were used for induction , while consolidation used standard cytarabine 3 gm/m2 twice daily days 1, 3, 5 for a total of 4 cycles. This is a Simon 1-stage design with a safety analysis after enrolling 12 pts, and an interim analysis after enrolling 18 out of 43 pts. If 11 or fewer pts achieve complete remission, the regimen will be considered ineffective. Results: Eighteen pts have been enrolled between July 2013 and July 2015, 17 of which have baseline data. Median age was 58 years (range 24-65) with 76.5% being male. Median laboratory findings include hemoglobin of 9.3 gm/dL, platelets of 52 x109, and white blood count of 7.0 (0.5-125). Cytogenetics were normal in 41% of the pts. Favorable cytogenetics were seen in 2 pts (inv 16). FLT3 testing was done on 15 pts and was positive in 27%. KIT gene sequencing (exon 8, 9, 10, 11, 17) revealed no pathogenic mutation. Median number of cycles was 3 (range 1-7). Six pts had treatment delays, with 2/13 (15%) delays being due to non-hematologic toxicities. No delays or missed doses affected cytarabine and daunorubicin administration. Out of 15 pts evaluable for response, 12 (80%) achieved CR (or CR with incomplete platelet recovery). Six of the 12 pts (50%) who achieved remission needed a second induction on protocol. Two out of 15 did not respond (did not get re-induction on protocol). One pt died before disease assessment due to liver failure (G5, had only one dose of nilotinib and toxicity was attributed to daunorubicin). Of the 14 pts having at least 1 bone marrow biopsy, the overall CR rate was 86%. Five (33%) pts proceeded to allogeneic stem cell transplant, all are alive and none were able to initiate protocol nilotinib maintenance therapy. Only 2 out of 12 (17%) pts relapsed after achieving CR, one was secondary AML from myelodysplastic syndrome with complex karyotype and the other was therapy-related AML with t(9;11). Only 2 (11%) pts died at time of report. Thirteen pts were evaluated for adverse events (AE). Six pts had G4 non-hematological AEs. Five of 12 G4 AEs were related to infection, 2 were electrolyte imbalances, and 2 were heart failures. Most common G3 non-hematological AEs were febrile neutropenia (53%), hypophosphatemia (23%), hyperglycemia (23%), and hypertension (23%). In agreement with the favorable outcomes, the molecular target validation revealed that nilotinib treatment down-regulates the expression of KIT, Sp1, DNA methyltransferase (DNMT) 1, DNMT3a and DNMT3b. Conclusion: Combination daunorubicin and cytarabine with nilotinib (DATA) appears to be safe and effective. Interim results show an acceptable safety profile in the first 12 evaluable pts with most common AE being infection as expected. Thirty day mortality is acceptable (7%). DATA regimen has encouraging CR rates of 80% (intent to treat) and 86% in assessed pts, with half of the pts who achieved remission requiring 2 cycles of induction. Relapse rate seems to be low at 17%. We will continue accrual until all pts accrued for final results. Disclosures Al-Kali: Celgene: Research Funding. Off Label Use: This is a Phase II study of combination nilotinib to standard chemotherapy in patients diagnosed with AML.. Tibes:TetraLogic Pharmaceuticals: Research Funding.

Abstract Introduction: The BCR-ABL1 genomic fusion event in chronic myelogenous and B-lymphoblastic leukemias (CML, ALL) commonly produces the major chimeric transcript variants e13 (or e14)-a2 or e1-a2, which are translated respectively to p210 and p190 bcr-abl1 oncoproteins. However, substantial transcript heterogeneity is present including alternative splice forms in a given leukemia, as well as rare alternative chimeric transcript types. Relatively little is known regarding the molecular response of alternative transcript variants of BCR-ABL1 during tyrosine kinase inhibition (TKI) therapy, in part because of the lack of effective disease burden monitoring methods. We present an approach to detection of the various BCR-ABL1 mRNA types using a multiplex quantitative RT-PCR (QRT-PCR) methodology. This technique enables diagnosis and molecular tracking of unusual BCR-ABL1 variants and can improve our understanding of how these uncommon leukemias behave in response to TKI therapies. Furthermore, the method is more generally applicable for simultaneous QRT-PCR detection and measurement of different mRNA species. Methods: Patient samples for diagnostic evaluation were obtained and total RNA extraction was performed using the Qiagen RNeasy Mini Kit (Qiagen USA, Valencia, CA). Reverse transcription was done using Multiscribe Reverse Transcriptase (Life Technologies, Grand Island, NY). Eleven fluorescent primer and probe mixes were designed (e1a2-FAM, e6a2-Cyc 5, e13a2-FAM, e14a2-FAM, e19a2-Cyc 5, e1a3-FAM, e12a3-Cyc 5, e13a3-FAM, e14a3-FAM, e19a3-Cyc 5, and Gusb reference control-HEX). 10 uL reactions were performed (95 C X 10 min, 45 cycles of 95 C X 10 sec and 60 C X 30 sec) using four multiplex wells per sample. Double strand oligonucleotides (oligos) for each target type were synthesized (IDT, Coralville IA) and diluted in a range of 106, 105, 104, 103, 100, 10, 1 and 0.1 copies/uL. Results of the new multiplex QRT-PCR assay were compared against our standard method of qualitative multiplex RT-PCR and fluorescent probe hybridization. Results: Results for the target BCR-ABL1 oligo controls are summarized in the table. The data show a wide dynamic range of detection with reproducible copy number detection at very low level. All PCR targets had excellent correlation coefficients (R2) and good to excellent PCR efficiency. Specificity was excellent, except for some cross-reactivity of A3 templates. This minor interference did not detract from assay performance or interpretation. Thirty-two patient samples were evaluated using the multiplex QRT-PCR assay and the current lab method. For 13 known BCR-ABL1 negative and 19 positive patient samples, concordance/accuracy and specificity were 100%. Furthermore, relative quantification of transcript abundance was obtained by the multiplex QRT-PCR approach, enabling distinction between diagnostic and post-treatment mRNA levels. Alternative splicing events producing additional transcripts (e1-a2) were resolved in the same specimen and always quantified well below the primary transcript level. Table 1.Transcript TypeDynamic Range(log)Sensitivity(copies/uL)Specificity(%)R2Efficiencye1-a2 (p190)6101000.971.74e6-a2 (p195)711000.951.76e13-a2/ e14-a2 (p210)61010011.99e19-a2 (p230)610E19A3 also detected0.991.89e1-a3 (p190)6101000.981.90e13-a3/ e14-a3 (p210)610E12A3 also detected11.99e12-a3410001000.991.78e19-a3 (p230)61010011.95 Conclusions: We demonstrate a powerful and relatively simple method for concurrent detection and quantitative measurement of multiple common and unusual alternative BCR-ABL1 mRNA transcripts. The results of this study provide a basis for more detailed monitoring of molecular disease levels during TKI therapy in leukemic patients with rare BCR-ABL1 types, and in turn, potentially enhance the ability to more optimally individualize clinical management for these patients. The platform is flexible and novel BCR-ABL1 transcript types can also be incorporated relatively easily. A similar strategy is applicable to the detection of chimeric mRNA species in other types of leukemias. Our approach can also be used to evaluate targeted RNA expression profiles of other prognostic or theranostic tumor markers in individual patients. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1122 Background: Continuous flow left ventricular assist device (CF-LVAD) recipients have increased tendency of post-surgical bleeding. We have previously described a universal loss of high molecular weight VWF multimers (HMWM), likely due to enhanced cleavage of the HMWM in CF-LVAD recipients. Among various VWF laboratory tests, VWF multimer analysis remains the reference method for detecting such an acquired VWF abnormality (AVWA). We hypothesize that the severity of AVWA is a predictor for bleeding tendency. In this study, using our in-gel VWF multimer electrophoresis method, we measured the severity of HMWM loss in CF-LVAD recipients by infra-red densitometry analysis and examined its association with other VWF activity test results and patients' bleeding tendency. Design: As part of an on-going prospective multicenter study, pre- and/or post-CF-LVAD implantation (7, 30 days and 5–7 months) blood samples were collected from 20 LVAD recipients during 2008 and 2009. Their clinically significant bleeding episodes were recorded. Plasma VWF antigen (VWF:Ag), VWF:Lx activity [Chen D, et al. J Thromb Haemost. 2011;9(10):1993–2002] and plasma VWF multimer analyses [Pruthi RK, et al. Thromb Res. 2010;126(6):543–9] were performed on all available plasma samples. VWF multimers were quantified by infra-red fluorescent densitometry analysis using Odyssey Infrared Imager version 2.0. VWF:multi ratio defined by density ratio between the high molecular weight multimer (HMWM, bands 11 and above) and low and intermediate molecular weight multimer (band 2 to 9) was calculated. Normal range of VWF:multi ratio was determined from 16 normal donor plasma and 4 pooled normal plasma. Statistical analyses including t-test and kappa test were employed. Result: The normal range of VWF:multi ratio is 0.4–0.76. The CV of VWF:multi ratio of a pooled normal plasma tested in 21 gel runs is 12%. Loss of VWF HMWM is present in three patients before CF-LVAD implantation and all patients after implantation. All samples with loss of HMWM show decreased VWF:multi ratio (<0.4). At a cut-off value of 0.4, the sensitivity and specificity of VWF:multi ratio for detecting HMWM loss are 100% and 95.5% respectively (n=67). Decrease of VWF:multi ratio is observed after implantation (0.41±0.07 pre- vs. 0.29±0.07 post-implantation, P<0.00001). In four patients who received heart transplantation, normalization of VWF multimer pattern and VWF:multi ratio (0.54±0.06) is observed. Ten patients had significant post-implantation bleeding episodes that are associated with significantly decreased VWF:multi ratio (0.26±0.04 bleeding vs. 0.32±0.09 non-bleeding, P=0.002) and VWF Lx/Ag ratio (0.72±0.10 bleeding vs 0.80±0.09 non-bleeding, P=0.001). At a cut-off of 0.26, VWF:multi ratio demonstrates a sensitivity of 64% and specificity of 85.7% for predicting clinically significant bleeding. The VWF:multi ratio shows moderate agreement with VWF:Lx/Ag ratio (Kappa value 0.42). Conclusions: Severity of VWF HMWM losses can be quantitatively measured by the new in-gel infra-red densitometry method (VWF:multi ratio). Severity of VWF HMWM losses defined by the VWF:multi ratios, along with VWF:Lx/Ag ratios are significantly associated with bleeding tendency in LVAD recipients. Disclosures: Milano: Thoratec: Consultancy.

Abstract Background Congenital/hereditary qualitative platelet disorders (CQPD) can be classified by platelet count (eg, normal or decreased) and platelet size as well as by functional defect. Based on mean platelet volume (MPV), congenital thrombocytopenias (CT) are classified as macro-thrombocytopenias (eg, Bernard-Soulier syndrome [BSS], MYH-9 [myosin heavy chain 9, non-muscle]-associated thrombocytopenias, gray platelet syndrome [GPS], etc.); microthrombocytopenias (eg, Wiskott-Aldrich syndrome and variants); and those with normal platelet size. CQPDs with normal platelet count include Glanzmann thrombasthenia (GT), dense granule storage pool disorders (DG-SPD) including Hermansky-Pudlak syndrome (HPS), platelet secretion disorders and many others. Diagnosis has relied on platelet counting and sizing, blood smear light microscopy, platelet aggregation (agg) and platelet function analyzer (PFA-100) studies. Platelet transmission electron microscopy (PTEM) and flow cytometry can provide supplementary information and molecular analysis is also evolving. The objective of this study was to determine the roles of platelet transmission electron microscopy (PTEM) and flow cytometry in the diagnosis of CQPD and CT. Methods In this retrospective cohort study, after IRB approval, the electronic medical record system was queried for patients (pt) with a confirmed CQPD or CT seen at Mayo Clinic between 2000 and 2015. A detailed chart review was undertaken. Results 54 pt (64% female) met our study criteria; median age was 32 years (range 1 day to 81 years). 18/54 (33%) pt had macrothrombocytopenia: BSS 4 (7%); MYH-9 10 (19%); gray platelet syndrome 4 (7%). 36/54 (66%) had normal MPV: Glanzmann thrombasthenia 6 (11%); storage pool disorders including DG-SPD 10 (19%) and HPS 2 (3%), mild alpha granule deficiency 3 (6%) and York platelet syndrome 4 (7%); platelet secretion disorders 4 (7%); ANKRD26 mutation 3 (6%); congenital amegakaryocytic thrombocytopenia 1 (2%); GATA-1 mutation 1 (2%); RUNX-1 mutation 1 (2%); and Jacobsen syndrome 1 (2%). 44 pt (81%) had a positive bleeding history: epistaxis 52%, cutaneous bleeding 57%, gastrointestinal bleeding 21% and menorrhagia 54%; 10 pt (19%) had a negative bleeding history. Results of standard and esoteric platelet testing are summarized in Table 1. Diagnosis in the 10 pt with glycoprotein deficiency (BSS or GT) was established by agg; flow cytometry was confirmatory but not necessary. Of the 23 pt with SPD, 5 had a negative bleeding history; 4 pt had normal agg and PFA-100 and were diagnosed exclusively by PTEM. In this group, the abnormalities on platelet aggregation and PFA were variable and PTEM allowed for a better definition of the specific abnormalities. For MYH-9 patients, PTEM confirmed leukocyte inclusions that had already been identified on light microscopy. PTEM was the only diagnostic modality able to identify the abnormality in York platelet syndrome. In 5/54 (9%) genetic testing was necessary for diagnosis (GATA-1, ANKRD26 and RUNX-1) Conclusion In this cohort, standard platelet assays established the diagnosis in the large majority of CQPD and CT. PTEM was essential for confirmation in DG-SPD, mild alpha granule deficiency and York platelet syndrome and useful in combination with molecular testing to establish a diagnosis in selected cases. Guidance on selection of patients for such specialized testing requires further study. Table 1. Results of standard and esoteric platelet testing for 54 patients with congenital qualitative platelet disorders and/or thrombocytopenia Disorder n (%) Platelet aggregation PFA PTEM Flow cytometry Confirmation by genetics Done Abnormal Done Abnormal Done Abnormal Done Abnormal Glanzmann thrombasthenia 6 (11) 6 6 5 5 1 0 3 3 0 Bernard-Soulier syndrome & variants 4 (7) 4 4 4 4 3 0 4 4 0 MYH-9 related disorders 10 (19) 7 2 8 3 5 5 4 2 5 Dense granule deficiency and HPS 12 (22) 12 8 12 8 12 12 4 0 0 Alpha granule deficiency* 7 (13) 7 4 7 6 7 7 4 4 1 York platelet syndrome 4 (7) 1 0 1 1 4 4 1 1 0 TXA2 or PG synthesis/receptor defect 4 (7) 4 4 4 3 3 0 3 0 0 CATM 1 (2) 0 - 0 - 0 - 0 - 1 ANKRD26 3 (6) 3 3 3 2 3 3 3 3 3 GATA-1 1 (2) 0 - 1 1 1 1 1 1 1 RUNX-1 1 (2) 1 0 1 1 0 - 0 - 1 Jacobsen syndrome 1 (2) 1 0 1 1 1 1 1 0 1 MYH-9: myosin heavy chain 9, non-muscle (MHY-9) associated thrombocytopenia, HPS: Hermansky-Pudlak Syndrome, TXA2: thromboxane A2, PG: prostaglandin CATM: congenital amegakaryocytic thrombocytopenia. * Includes gray platelet syndrome Disclosures Pardanani: Stemline: Research Funding.

AbstractBackgroundAngioimmunoblastic T‐cell lymphoma (AITL) is a systemic peripheral T‐cell lymphoma with a follicular helper T‐cell (TFH) immunophenotype that frequently involves the skin. However, the histopathology of cutaneous involvement by AITL has not been fully established.MethodsWe reviewed the clinicopathological features of 19 patients seen at our institution with AITL involving the skin. Pan‐T‐cell and TFH marker expression was evaluated by immunohistochemistry. Epstein‐Barr virus (EBV) was detected using in situ hybridization (ISH) for Epstein‐Barr virus‐encoded small RNA (EBER). T‐cell receptor (TCR) gene rearrangement was evaluated by PCR.ResultsAITL affected both trunk and extremities in 15/19 cases (79%). Perivascular infiltration by small and/or medium‐sized lymphocytes was seen in 18/19 (95%). Granulomatous inflammation was identified in 4/19 (21%). Aberrant loss of CD2, CD5, or CD7 was identified in 1/18 (6%), 2/18 (11%), or 7/19 (37%) cases, respectively. Seventeen of eighteen evaluable cases (95%) expressed 2 to 3 TFH markers: PD‐1 in 19/19 (100%), BCL6 in 94% (17/18), and CD10 in 37% (7/19). EBV‐positive cells were detected in 3/18 (17%) with varying density. Clonal TCR gene rearrangement was identified in 9/11 (82%).ConclusionsCutaneous involvement by AITL shows relatively non‐specific histopathological features. However, an immunohistochemical panel including TFH markers and EBER ISH is useful in differential diagnosis.