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Leukemic involvement in high grade B cell lymphoma (L-HGBL) is rare and has been sparsely described in the literature. We report our experience in a large single institution multicenter academic setting.Medical records of patients with HGBL who received care at Mayo Clinic between 2003 and 2020 were reviewed. L-HGBL was confirmed by peripheral blood smear and flow cytometry with corroboration from tissue and bone marrow biopsy findings.Twenty patients met inclusion criteria. All patients had significant bone marrow involvement by HGBL. Leukemic involvement presented in 11 of 20 (55%) in the de novo and 9 of 20 (45%) in the relapsed setting. Seven of 20 patients had DLBCL, NOS, 6 of 20 had transformation (t-DLBCL), 3 of 20 had transformed double/triple hit lymphoma (t-DHL/THL), 2 of 20 had double hit lymphoma (DHL), and 2 of 20 had HGBL with intermediate features between DLBCL and Burkitt lymphoma. Nine of 15 patients had MYC translocation. Based on Hans criteria, 11 of 20 had germinal center B-cell (GCB) cell of origin (COO) and 9/20 had non-GCB COO. Five of 11 de novo patients experienced CNS relapse/progression. All de novo patients received anthracycline-based chemoimmunotherapy. Eighteen of 20 patients died of progressive disease. Median overall survival was significantly better in the de novo compared to relapsed group (8.9 months vs. 2.8 months, P = .01). COO, MYC status, DHL/THL status, HGBL subtype, or treatment group did not demonstrate a significant effect on overall survival.L-HGBL carries a poor prognosis and is associated with MYC translocation, DHL/THL status, transformation, and high CNS risk. Novel therapeutic approaches are needed for L-HGBL.

Jing Wang,1 Muhamad Alhaj Moustafa,2 Justin J Kuhlman,1 Karan Seegobin,2 Liuyan Jiang,3 Vivek Gupta,4 Han W Tun2 1Department of Internal Medicine, Mayo Clinic Florida, Jacksonville, FL, 32224, USA; 2Division of Hematology and Medical Oncology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA; 3Department of Pathology and Laboratory Medicine, Mayo Clinic Florida, Jacksonville, FL, 32224, USA; 4Department of Radiology, Mayo Clinic Florida, Jacksonville, FL, 32224, USACorrespondence: Han W Tun, Mayo Clinic Florida Division of Hematology/Oncology, 4500 San Pablo Road S, Jacksonville, FL, 32224, USA, Tel +1 904-953-2000, Email tun.han@mayo.eduAbstract: Intravascular large B cell lymphoma (IVL) is a rare subtype of diffuse large B cell lymphoma confined to small blood vessels with a predilection for CNS involvement. The prognosis of IVL with CNS involvement (CNS-IVL) is extremely poor. The optimal treatment for CNS-IVL is not well defined. Thus, we report three patients with CNS-IVL successfully treated with a CNS-centric approach consisting of high-dose methotrexate (HDMTX) and high-dose Ara-C (HiDAC) based CNS-directed chemoimmunotherapy (CIT) alternating with anthracycline-based CIT. Our rationale for intensifying the CNS-directed therapy is the presence of intracerebral bleeding in two of our patients which would result in extravasation of lymphoma cells into the cerebral parenchyma with the development of CNS lymphoma. All three patients have achieved excellent therapeutic outcomes. Two patients with intracerebral bleeding have been in complete remission (CR) for about 11 years and 4 years. One patient was successfully induced into CR about 10 months ago and currently is in CR. This unique therapeutic approach should be further explored for CNS-IVL.Keywords: intravascular lymphoma, CNS involvement, CNS-directed chemoimmunotherapy, anthracycline-based chemoimmunotherapy, high-dose methotrexate, high-dose Ara-C

Effects of Crotalinae envenomation vary by geographical areas and research into coagulopathy and effects of antivenom are needed to optimize management. This was a single-center retrospective review with testing on presentation and 4 h after; antivenom administration was noted and data analyzed overall and comparing envenomations. One hundred and nineteen snakebites evaluated with 59 identified as Crotalinae and half receiving antivenom. PT/aPTT was elevated in 20% of water moccasin/copperhead and 21% of rattlesnake bites. DIC-like syndrome occurred in 8% water moccasin/copperhead and 6% rattlesnake bites. Antivenom did not seem to correct PT or aPTT at 4 h follow-up in most cases. Thrombotic microangiopathy was not seen. Coagulopathy was prevalent affecting one in five patients in this cohort and does seem to persist at short interval follow-up, even in those receiving antivenom. We support guidelines recommending clinical monitoring and serial coagulation profiles in such cases. Blood Coagul Fibrinolysis 30:000 - 000 Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.

Karan Seegobin,1 Muhamad Alhaj Moustafa,1 Umair Majeed,1 Jordan C Ray,2 Marwan Shaikh,1 Liuyan Jiang,3 Han W Tun1 1Department of Hematology and Medical Oncology, Mayo Clinic, Jacksonville, FL, 32224, USA; 2Departmentof Cardio-Oncology, Mayo Clinic, Jacksonville, FL, 32224, USA; 3Department of Pathology, Mayo Clinic, Jacksonville, FL, 32224, USACorrespondence: Han W TunDepartment of Hematology and Medical Oncology, Mayo Clinic Hospital, Jacksonville, FL, 32224, USAEmail Tun.Han@mayo.eduAbstract: Macrophage activation leading to multi-organ dysfunction/failure has been described in various hematologic disorders like hemophagocytic lympho-histiocytosis (HLH), also known as macrophage activation syndrome (MAS) and macrophage activation like syndrome (MALS). Congestive heart failure (CHF) appears to be an uncommon manifestation of macrophage activation. This novel entity of macrophage activation-associated cytokine-mediated CHF has not been well reported in the medical literature. We report two young female patients with acute CHF secondary to macrophage activation-associated cytokine storm. An extensive diagnostic workup was negative for other etiologies, such as ischemia, myocarditis, or infections. Their clinical, laboratory, and pathologic findings did not meet the diagnostic criteria for hemophagocytic syndrome (HPS)/MAS. However, both had laboratory and pathologic findings which were consistent with macrophage activation and cytokine storm. One patient met criteria for MALS. Therapeutically, our patients were promptly treated with steroids with or without anti-cytokine therapy with rapid restoration of cardiac function. Macrophage activation-induced disease may not always fulfil the diagnostic criteria for the currently known macrophage activation disorders. We suggest that markers of macrophage activation and cytokine levels should be part of the diagnostic workup in patients with otherwise unexplained acute CHF. Additional research is warranted to further elucidate the underlying mechanism of this disorder.Keywords: macrophage activation syndrome, MAS, macrophage activation like syndrome, MALS, cytokine release storm, CRS, reversible systolic heart failure, immunosuppression

Intravascular lymphoma (IVL) is a rare extranodal non-Hodgkin lymphoma. We performed a retrospective analysis of 55 IVL patients who were treated at our institution 2003-2018. Median age at diagnosis was 68 years, and 64% were males. The most frequent presenting symptoms were skin rash 43% and weight loss 30%. MRI brain on IVL patients with CNS involvement (CNS-IVL) showed multifocal involvement in 76% (13/17). 89% (17/19) of non-CNS-IVL patients with abnormal FDG-PET had biopsy of an avid lesion resulting in definitive diagnosis. The top diagnostic biopsy site was the bone marrow (45%). 56% had multiorgan involvement. Based on CNS involvement, 36.5% (20/55) had CNS-IVL and 63.5% (35/55) had non-CNS-IVL. CNS-IVL group consists of clinically isolated CNS involvement (CNS-only IVL) (22%;12/55) and mixed clinical CNS and peripheral site involvement (M-IVL) (14.5%; 8/55). Non-CNS-IVL group consists of clinically isolated skin involvement (skin-only IVL) (9%; 5/55) and peripheral IVL with or without skin involvement (P-IVL); (54.5%; 30/55). Skin involvement was predominantly in the lower extremities. Pathologically, 89% (48/54) were B-cell IVL. Rituximab + high-dose methotrexate-based regimen were used in 75% (12/16) of CNS-IVL patients and RCHOP in 60% (17/28) of non-CNS-IVL patients. Estimated 5-year progression free survival (PFS) and overall survival (OS) for the entire cohort were 38.6% and 52%, respectively. Skin-only IVL was associated with excellent survival. Platelet count150x10

IgG4‐related disease (IgG4RD) with intracranial involvement is rare. We report a 56‐year‐old male who had an excellent response to rituximab and dexamethasone after going undiagnosed for 5 years. After 3 years of rituximab maintenance, he has no evidence of disease on brain MRI., Hypertrophic pachymeningitis is a rare manifestation of IgG4‐related disease and is usually responsive to treatment with rituximab and dexamethasone. Maintenance rituximab can be considered to prevent relapse of disease after an initial response.

Breast cancer is a common entity that can be difficult to diagnose. This case demonstrates the limitations of breast cancer diagnostics. Particularly, how the available imaging techniques and even biopsy can potentially miss a malignancy. It exemplifies the role immunohistochemistry staining plays in the diagnosis of cancers of unclear origin.

With the advent of targeted therapy for non-small-cell lung cancer, there are many new available treatment options for patients whose cancer harbors an actionable mutation or alteration. These new medications come with numerous side effects, for some of which, the management is not well defined. Alectinib is a second-generation tyrosine kinase inhibitor approved for stage-IV lung adenocarcinoma with anaplastic lymphoma kinase gene rearrangement. Severe (⩾Grade 3) skin rash is a rare side effect of alectinib. Reintroducing alectinib in patients with severe skin rash is not well defined in the medical literature. While other case reports have outlined their approach and desensitization protocol, the maximum dose that patients were titrated up to in a desensitization protocol was 300 mg twice daily. Here, we report a case of Grade 3 skin rash secondary to alectinib, and our experience in managing the rash and reintroducing alectinib with a unique desensitization protocol to a max of 600 mg twice daily (full dose). This case could provide further guidance to oncologists managing patients with this adverse event and may aid in reducing concerns to both patients and physicians about recurrence of skin rash at the maximum dose.

New primary cancers can occur in patients with a previous cancer. Among the risk factors, therapies such as chemotherapy, radiotherapy, and hormonal therapy have been associated with the development of neoplasms. Second cancers most commonly develop 5–10 years after the initial tumor. We observe the implications of cancer-related therapy in the development of a new tumor. We looked at 602 patients who had their first cancer diagnosed in 2011 and calculated the number of different primary cancers between 2011 and 2016 for each patient. Twenty-four patients had a second cancer within 5 years from the first diagnosis and there were no patients with a third cancer. There was no statically significant difference in the rates of second cancers after exposure to chemotherapy, radiotherapy, hormonal therapy, or any combination of these (p=0.738). Of the second cancers reported after 2011, renal, uterine, cervical, and lung cancers were the most frequently reported. Additionally, there was no statically significant difference among the rates of second cancers in men versus women (p=0.467), as well as among whites versus blacks (p=0.318). We conclude that while new primaries can occur after one cancer, there was no increased risk after exposure to different cancer-related therapies. With increased focus on the primary disease, there is a higher likelihood of missing another primary lesion. This is important as the practical implications of managing multiple primaries are rarely discussed.

Introduction: Intravascular lymphoma (IVL) is an extra nodal non-Hodgkin lymphoma with tropism for vascular endothelium. It is characterized by growth of large cells within the lumen of small to medium sized blood vessels. Central nervous system (CNS) and skin are predominantly involved. This report represents a retrospective single-institution review of IVL. Methods: We identified patients (pts) with IVL evaluated at Mayo Clinic Cancer Center between January 2003 and December 2018. Demographic, clinical, radiologic, pathologic, and therapeutic data were extracted. Statistical analysis of overall survival (OS) and progression free survival (PFS)] was performed using Kaplan-Meier method. Results: Total number of pts was 55; 22% (12/55) had CNS-only IVL, 14.5% (8/55) had CNS and non-CNS IVL, and 63.6% (35/55) had non-CNS IVL. Eighty seven percent (47/54) pts were B cell type, 11% (6/54) were T cell type, one pt had NK cell type IVL and another was unknown. Four pts were diagnosed by autopsy. Median age at diagnosis was 68 years (range, 40-85). Sixty-four percent were males. ECOG performance status was The median follow-up time from diagnosis was 63 months [CI 95%, 9-NR], and 47% (26/55) were alive. The most common diagnostic biopsy sites were bone marrow (BM) 45% (25/55), skin 25% (14/55), and brain 29% (16/55). Twenty-nine patients had a PET scan. Seventy nine percent (23/29) had abnormal PET findings, with mean SUV of 8.6 (range 2.5-19.1). Of the 35 pts with non-CNS IVL, 76% (16/21) had abnormal PET; furthermore, the diagnosis was made with biopsies of the following sites: bone marrow 54% (19/35), skin 40% (14/35), lung 14% (5/35), liver 5.7% (2/35), spleen 2.8% (1/35), and omentum 2.8% (1/35). Forty-six percent (13/28) received CNS prophylaxis and ten percent (3/55) had relapse in CNS. Two out of the three pts who had CNS relapse had received CNS prophylaxis. The median time to CNS relapse in non-CNS IVL was 9 months. The most common first-line regimen was high-dose methotrexate+ rituximab containing regimen 62% (10/16) in IVL with CNS involvement and RCHOP (60%) (17/28) in non-CNS IVL. Seventeen percent of (8/48) pts received autologous stem cell transplant (ASCT) and 63% (5/8) pts were transplanted in first complete remission (CR1), and 3 pts after the first relapse. Median OS (mOS) for the whole cohort was 57 months, [CI 95%, 9-NR], and median PFS was 7 months [CI 95%, 2-NR]. There was no significant difference in mOS between groups; CNS-only IVL- 9 months (CI 95%, 1-NR), non-CNS IVL -62 months (CI 95%, 20-NR) vs combined CNS and non-CNS IVL- 4 months (CI 95%, 3-NR). mOS for those who received ASCT in CR1 was not reached (CI 95%, 10-NR) vs 51 months in non-transplant group (CI 95%, 3-NR) p=0.24. In pts with non-CNS IVL, there was no significant difference in mOS between CNS prophylaxis subgroup (NR: CI 95%, 57-NR) vs no-CNS prophylaxis subgroup (20 months: CI 95%, 0-NR), p=0.12. In those with CNS IVL mOS for early diagnosis (0-30 days from symptom onset to diagnosis was NR (CI 95%, 3-NR) vs mOS for late diagnosis (>30 days {31-14,440})-5months (CI 95% 1-NR), p=0.29]. Conclusion: 1. BM was most frequently involved in our patients. We suggest that BM biopsy should be part of diagnostic testing when IVL is suspected. 2. Most cases are of B-cell linage, consistent with reported literature. All non-B cell cases were in non-CNS locations. 3. PET scans were abnormal in more than 70% of cases indicating that this imaging modality is vital in the diagnosis due to odd location and small size of lesions. 4.Overall prognosis in the literature was poor with most patients surviving 5. CNS involvement had an overall trend towards poor prognosis; however, those diagnosed early had better outcomes; this did not reach statistical significance due to small sample size. 6. mOS was not reached for those transplanted CR1. There was a trend towards a better survival associated with CNS prophylaxis versus no prophylaxis in non-CNS IVL. 7. We suggest that CNS-centric therapeutic approach and intensive consolidation with ASCT should be considered in managing IVL. Figure 1 Figure 1. Disclosures Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Habermann: Incyte: Other: Scientific Advisory Board; Seagen: Other: Data Monitoring Committee; Tess Therapeutics: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Tun: Mundipharma, Celgene, BMS, Acrotech, TG therapeutics, Curis, DTRM: Research Funding; Gossamer Bio, Acrotech: Consultancy.

A 52-year-old man with a past medical history of chronic myeloid leukemia (CML) in remission developed progressive shortness of breath over a two-month period. He was initially treated with dasatinib for four years, until developing pulmonary arterial hypertension (PAH) with pleural effusions. His symptoms improved after stopping dasatinib. He was then switched to bosutinib for approximately one year, which was then stopped before admission due to worsening shortness of breath. His initial workup showed bilateral pleural effusions with severe PAH and cor pulmonale. He had symptomatic improvement with PAH-specific therapy following discontinuation of the bosutinib. The life expectancy of CML patients has increased in the era of the tyrosine kinase inhibitors (TKIs), and managing adverse events (AEs) of the TKIs and improving quality of life are becoming more important. Pulmonary hypertension (PH) and pleural effusions are rarely reported AEs of bosutinib. More reports with PH and pleural effusions arising after bosutinib use in patients previously treated with dasatinib is furthermore concerning. In this era with novel chemotherapeutic agents, physicians ought to be weary of the significant morbidity implicated by these agents in the lives of patients.

Background: Acute chest syndrome (ACS) frequently complicates sickle cell disease (SCD) and is a leading cause of hospitalization and mortality. Many factors have been implicated in ACS, including infections, thrombosis, fat and pulmonary emboli. However, a clear etiology is not defined in 50% of the cases and ACS is considered a clinical endpoint for different pathogenic processes (Vichinsky et al 2000). The non-specific nature of ACS makes diagnostic tests challenging, and there are no serum tests clinical used to aid diagnosis. Procalcitonin (PCT) is a prohormone of calcitonin and serum PCT rises within hours of an inflammatory stimulus. PCT has clinical utility as a marker of severe systemic inflammation, infection, and sepsis (Becker et al. 2008). Few studies have evaluated PCT as a biomarker for ACS in patients presenting with vaso-occlusive crises (VOC). Two studies have reported no difference in PCT (Biemond et al. 2018 and Stankovic et al 2011), while one study reported higher PCT between ACS and VOC (Patel et al 2014). Methods: We retrospectively reviewed 106 patients with SCD who presented to the emergency department with fever and painful crises during 2015-2019. The patients were divided into two categories based on discharge diagnoses - patients with VOC only (n=88) and patients with ACS (n=18). Inclusion criteria for both groups were patients with SCD, 17 years and older and PCT measurement on presentation. Exclusion criteria were defined as patients who had received empiric antibiotics prior to PCT testing. Data collected on presentation included genotype, age, gender, complete blood count, PCT, creatinine, total bilirubin and hydroxyurea use. Length of stay was recorded. Data was analyzed between the two groups using descriptive statistics and accounting for unequal variances, withp-value set at 0.05 for significance. Results: Demographics and clinical characteristics are summarized in Table 1 (Figure). The sample included primarily adult males (77%), with about two-thirds on hydroxyurea. Genotype HbSS (73.6%) was most prevalent followed by HbSC (22.6%) and HbSβ (3.8%). The ACS group had a higher percentage of HbSS, lower use of hydroxyurea and higher mean bilirubin. Mean PCT for the ACS group was 0.52 ng/mL (range, 0.05-2.04), compared to 0.31 ng/mL (range, 0.02-6.82) in the VOC group; withp=0.084. ROC analysis showed a PCT>0.5ng/mL had 39% sensitivity and 85% specificity for ACS in this sample. Conclusion: In this sample, PCT on presentation was higher in those with ACS compared to VOC, but this difference did not achieve statistical significance. Further study in a larger population would be useful to evaluate this finding. Disclosures No relevant conflicts of interest to declare.

A 59-year-old man presented to the emergency department with pain and ulceration of several fingers on the right hand. He reported no history of trauma. His medical history was significant for chronic kidney disease, coronary atherosclerosis, ischemic cardiomyopathy, and hypertension. He described

e19552 Background: Leukemic involvement (LI) in diffuse large B cell lymphoma (L-DLBCL) is very rare and has been sparsely reported. We report our experience with this entity in a large academic multi-center setting. Methods: Medical records of patients with DLBCL who received care at Mayo Clinic between 1/2003 and 6/2020 were reviewed. DLBCL patients with LI were identified. LI was defined as increased white blood cell counts and the presence of clonal B cells on peripheral blood flow-cytometry. Kaplan-Meier method was used for survival analysis. Results: Twenty patients with L-DLBCL were identified with a median follow-up of 32.5 months (CI95%, 32.5-NR). Median age at initial diagnosis was 62 (45-80) years. 60% (12/20) were male; 90% (18/20) were Caucasian. Pathologically, 90% (18/20) had DLBCL and 10% (2/20) had high-grade B cell lymphoma (HGBCL) with intermediate features between DLBCL and Burkitt lymphoma. By Hans criteria, 58% (11/19) had germinal center B-cell DLBCL (GCB-DLBCL) and 42% (8/19) had non-germinal center B-cell DLBCL (non-GCB-DLBCL). 40% (8/20) had transformed DLBCL (t-DLBCL); 36% (5/14) had double-hit lymphoma (DHL) by FISH analysis. LI was present in 55% (11/20) at initial diagnosis and 45% (9/20) at relapse. Median WBC was 39.5/ul (range, 4.3-121) with median absolute lymphocyte count of 25 k/ul (range, 0.7-117). Immunophenotypically, the leukemic lymphoma cells expressed CD19, CD20, and CD79a. Bone marrow involvement and pancytopenia were documented in all patients with a median bone marrow cellularity of 80%. Other extranodal sites of involvement with LI included spleen (65%;13/20), liver (20%;4/20), breast and soft tissue (20%;4/20), bladder or kidneys (10%;2/20), skeleton (10%;2/20), and myocardium (5%;1/20). 65% (13/20) had B-symptoms. All patients had LDH elevation (UNL 222 U/L) with a median of 2125 U/L (range, 308-10,760). 45% (5/11) of patients with LI at initial diagnosis had CNS involvement on relapse/progression. All patients with LI at initial diagnosis received anthracycline-based chemoimmunotherapy with or without CNS prophylaxis. Patients with LI at relapse had had a median of 2 prior treatments (range, 1-5) before LI. Median overall survival (OS) for the whole group was 9 months (CI 95%; 5.8-11.8). There were no long-term survivors. Median progression free survival after LI was 4.7 months (CI95%; 0.8-7.6) in the newly diagnosed group and 3 months (CI95%; 0.9-20) in the relapsed group. 90% (18/20) died due to their progressive disease. Cell of origin, DHL status, or newly diagnosed vs. relapsed status did not have a significant impact on OS in patients with L-DLBCL. Conclusions: Leukemic involvement at any time during the course of DLBCL is associated with poor prognosis. It also appears to be a major risk factor for CNS relapse. It is most frequently associated with DHL and t-DLBCL. Novel therapeutic approaches at the time of initial therapy need to be developed for L-DLBCL.

Mycobacteria Bovis osteomyelitis is a rare adverse effect after Bacillus Calmette-Guerin (BCG) intravesical therapy. A 62-year-old male presented with acute spinal cord compression three months after completing his second course of therapy for bladder cancer. The first course with intravesical BCG was complicated with an episode of hematuria. He reported intermittent subjective fever for 3 weeks thereafter which resolved with Tylenol. Interferon-α2 B was added to the second cycle of intravesical BCG with the indication here being residual tumor, and was tolerated well. His complete blood count and liver function tests were unremarkable on admission. MRI showed features of osteomyelitis with cord compression at T4/T5. Biopsy of the affected bone showed caseating granuloma which was positive for acid fact bacilli, later confirmed to be Mycobacterium Bovis by PCR and pyrazinamide resistance. He was started on intravenous steroids and underwent spinal cord decompression. Rifampin, Isoniazid, and Ethambutol were then commenced. His weakness improved and after two months of therapy he was asymptomatic and back to his baseline function. Osteomyelitis is a rare but serious complication. Early diagnosis and treatment is important as the outcomes are good.

Primary immune thrombocytopenia (ITP) – also called idiopathic thrombocytopenic purpura or immune thrombocytopenic purpura – is an acquired thrombocytopenia caused by autoantibodies against platelet antigens. It is one of the more common causes of thrombocytopenia in otherwise asymptomatic adults. Rocky Mountain spotted fever (RMSF) is a potentially lethal, but curable, tick-borne disease. We present a case of ITP that was triggered by RMSF.

Background: Patients with sickle cell disease (SCD) are at increased risk of developing bacterial infections as a result of functional asplenia. Fever, a common symptom in SCD often occurs with other sickle cell related conditions and viral infections. This poses a diagnostic challenge and early use of empiric antibiotics is recommended while awaiting cultures. The widespread administration of antibiotics to all patients with SCD with fever can result in problems such as antibiotic resistance and increased medical costs. An early and reliable biomarker is therefore needed to help distinguish between bacterial and non-bacterial causes for fever in SCD. Procalcitonin (PCT) has been shown to be elevated in bacterial but not viral infections. In SCD, few studies have looked at the role of PCT in predicting bacterial infections. Unal et al reported vaso-occlusive crisis (VOC) with or without fever did not increase PCT levels in relation to patients with no crisis and no fever. However, Rincón-López et al reported a PCT < 0.6ng/mL had a negative predictive value of 97.2% and potentially could be used to identify bacterial infection early. Methods: We retrospectively studied 122 patients with SCD who presented to the emergency department with fever from 2015-2019. Inclusion criteria were defined as patients with SCD, 17 years and older and PCT measurement on presentation to the emergency department. Exclusion criteria were defined as patients with SCD and fever who had received empiric antibiotics prior to labs being drawn in the emergency department. The cohort was divided into groups of patients with Confirmed Bacterial Infection (CBI, n=18), Suspected Bacterial Infection (SBI, n=6), Viral Infections (n=10) and Vaso-Occlusive Crises (VOC, n=88) only. CBI was defined as a positive bacterial culture (blood, body fluid, urine, respiratory or cerebrospinal fluid) or C.difficile toxin assay. Viral infections were defined as a negative bacterial culture in the presence of a virus found on PCR obtained with nasopharyngeal swab. Characteristics including genotype, age, gender, complete blood count, PCT, creatinine, total bilirubin, hydroxyurea use and length of stay were examined. Data was analyzed between the groups using descriptive statistics and accounting for unequal variances, with p-value set at 0.05 for significance. Results: Demographics and clinical characteristics are summarized in Table 1 (Figure). The mean age was 34.6 years with predominantly males (64.8%). Almost two-thirds were on hydroxyurea (62.3%). The most common genotype was HbSS (70.5%) followed by HbSC (26.2%) and HbSβ (3.3%). The mean PCT for patients with CBI was 8.99 ng/mL (range, 0.03-78.36) as compared to 0.31 ng/mL (range, 0.02-6.82) in the VOC group. The most common organisms detected were E.coli, C.difficile, Pseudomonas, Staphylococcus and Enterobacter. There was a significant difference between median PCT for patients with CBI and those with VOC (p=0.036) and between patients with CBI and viral infections (p= 0.045). Using a PCT of >0.5ng/mL resulted in 81% Sensitivity and 85% Specificity for CBI. Conclusion: In patients with SCD presenting with fever, PCT on presentation was significantly higher in those with CBI compared to VOC only or Viral Infection. Disclosures No relevant conflicts of interest to declare.

Background: Approximately 5000 snake bites are reported in the United States (US) annually with half of these patients being admitted. Crotalinae species are the most numerous; coral and imported exotic snakes cause a smaller number. Snake venoms are highly stable chemically complex mixtures of proteins. Quantity and composition vary with species and geographic location. Although enzymes contribute to the deleterious effects of the venom, the lethal components may be the smaller low molecular-weight polypeptides. Crotalinae envenomation is known to contain thrombin-like glycoproteins that can induce coagulopathy ranging from asymptomatic lab abnormality to disseminated intravascular coagulopathy (DIC) and life-threatening hemorrhage. In certain geographical areas of the United States thrombocytopenia, hypofibrinogenemia and coagulopathy are common hematological abnormalities, and ones that dictate both a reason for treatment with antivenom as well as an important monitor of therapeutic efficacy. Data on hematological abnormalities following envenomation by crotaline species in Northeast Florida/Southwest Georgia has not been reported before. Methods: We conducted a retrospective review of envenomations that presented to the University of Florida at Jacksonville from April 2013 to October 2018. Patients had to be 16 years or older without any pre-existing hematologic disorder or use of anticoagulant medications. Data including Complete Blood Count, Prothrombin Time (PT), activated Partial Thromboplastin Time (aPTT) and Fibrinogen were measured on presentation, and 4 hours after. Crotaline Fab antivenom (CroFab®) administration was noted if done. Adverse events associated with antivenom therapy, recurrence phenomena, delayed onset of symptoms, and performance of fasciotomy were also recorded. Results: Overall, 119 snakebites were evaluated. The majority were identified as Crotalinae - 25 water moccasin, copperhead or cottonmouth (Agkistrodon piscivorus, Agkistrodon contortrix) bites and 34 rattlesnake (Sistrurus miliarius, Crotalus adamanteus) bites. Male sex dominated the sample with most patients middle-aged (Table 1). More than 80% of patients arrived within 6 hours following the bite. Over 60% of patients received crotaline Fab antivenom. Results are presented in Table 2. Around 12% of patients with water moccasin, copperhead or cottonmouth (Agkistrodon piscivorus, Agkistrodon contortrix) bites had coagulopathy on admission. This compares similarly to data from South Carolina previously showing a 10.89% rate following copperhead bites (Qureshi et al. Blood 2010;116(21):4753). The rate of coagulopathy with rattlesnake bites was however much higher in North Florida at 20.6% - compared to 5.26% in the South Carolina series. Rates of DIC or severe hemorrhage were 8% for water moccasin, copperhead or cottonmouth (Agkistrodon piscivorus, Agkistrodon contortrix) bites and 5.9% for rattlesnake (Sistrurus miliarius, Crotalus adamanteus) bites. When hemostatic defects were looked at separately, the most common abnormality induced was PT/aPTT derangement, followed by hypofibrinogenemia and then thrombocytopenia. This pattern was the same as reported in South Carolina. Recurrence phenomena was observed after 4 hours in a number of patients, however the significance of this remains uncertain as most of these patients remained clinically stable without worsening symptoms. Anaphylactic reaction to the antivenom developed in one patient. Conclusions: In this sample from North Florida, deranged PT/aPTT was the most common hematologic abnormality following envenomation, followed by hypofibrinogenemia and a low rate of thrombocytopenia. Similarities with data from South Carolina were noted, although rattlesnake bites had 4 times higher incidence of coagulopathy in North Florida. DIC or severe hemorrhage was a notable toxicity, affecting 6-8% of Crotalinae cases. Hematologic effects of envenomation do seem to vary by geographic areas in the United States and physicians would benefit from local data to better manage these patients. Disclosures No relevant conflicts of interest to declare.