An age-progressive platelet differentiation path from hematopoietic stem cells causes exacerbated thrombosis.

Platelet dysregulation is drastically increased with advanced age and contributes to making cardiovascular disorders the leading cause of death of elderly humans. Here, we reveal a direct differentiation pathway from hematopoietic stem cells into platelets that is progressively propagated upon aging. Remarkably, the aging-enriched platelet path is decoupled from all other hematopoietic lineages, including erythropoiesis, and operates as an additional layer in parallel with canonical platelet production. This results in two molecularly and functionally distinct populations of megakaryocyte progenitors. The age-induced megakaryocyte progenitors have a profoundly enhanced capacity to engraft, expand, restore, and reconstitute platelets in situ and upon transplantation and produce an additional platelet population in old mice. The two pools of co-existing platelets cause age-related thrombocytosis and dramatically increased thrombosis in vivo. Strikingly, aging-enriched platelets are functionally hyper-reactive compared with the canonical platelet populations. These findings reveal stem cell-based aging as a mechanism for platelet dysregulation and age-induced thrombosis.

Interferon and myeloproliferative neoplasms: Evolving therapeutic approaches.

Interferons (IFNs) are a diverse group of cytokines whose potent antitumor effects have piqued the interest of scientists for decades. Some of the most sustained clinical accomplishments have been in the field of myeloproliferative neoplasms (MPNs). Here, we discuss how both historical and novel breakthroughs in our understanding of IFN function may lead to more effective therapies for MPNs. The particular relevance and importance of modulating the novel IFN-regulated ULK1 pathway to optimize IFN responses is highlighted.

ABCC4 impacts megakaryopoiesis and protects megakaryocytes against 6-mercaptopurine induced cytotoxicity.

The role of ABCC4, an ATP-binding cassette transporter, in the process of platelet formation, megakaryopoiesis, is unknown. Here, we show that ABCC4 is highly expressed in megakaryocytes (MKs). Mining of public genomic data (ATAC-seq and genome wide chromatin interactions, Hi-C) revealed that key megakaryopoiesis transcription factors (TFs) interacted with ABCC4 regulatory elements and likely accounted for high ABCC4 expression in MKs. Importantly these genomic interactions for ABCC4 ranked higher than for genes with known roles in megakaryopoiesis suggesting a role for ABCC4 in megakaryopoiesis. We then demonstrate that ABCC4 is required for optimal platelet formation as in vitro differentiation of fetal liver derived MKs from Abcc4-/- mice exhibited impaired proplatelet formation and polyploidization, features required for optimal megakaryopoiesis. Likewise, a human megakaryoblastic cell line, MEG-01 showed that acute ABCC4 inhibition markedly suppressed key processes in megakaryopoiesis and that these effects were related to reduced cAMP export and enhanced dissociation of a negative regulator of megakaryopoiesis, protein kinase A (PKA) from ABCC4. PKA activity concomitantly increased after ABCC4 inhibition which was coupled with significantly reduced GATA-1 expression, a TF needed for optimal megakaryopoiesis. Further, ABCC4 protected MKs from 6-mercaptopurine (6-MP) as Abcc4-/- mice show a profound reduction in MKs after 6-MP treatment. In total, our studies show that ABCC4 not only protects the MKs but is also required for maximal platelet production from MKs, suggesting modulation of ABCC4 function might be a potential therapeutic strategy to regulate platelet production.

Clinical utility of investigations in triple-negative thrombocytosis: A real-world, multicentre evaluation of UK practice.

Diagnosis of essential thrombocythaemia (ET) is challenging in patients lacking JAK2/CALR/MPL mutations. In a retrospective evaluation of 320 patients with 'triple-negative thrombocytosis', we assessed utility of bone marrow histology (90.9% of patients) and myeloid gene panel (MGP, 55.6%). Supportive histology ('myeloproliferative neoplasm-definite/probable', 36.8%) was associated with higher platelet counts and varied between centres. 14.6% MGP revealed significant variants: 3.4% JAK2/CALR/MPL and 11.2% other myeloid genes. Final clinical diagnosis was strongly predicted by histology, not MGP. 23.7% received cytoreduction (17.6% under 60 years). Real-world 'triple-negative' ET diagnosis currently depends heavily on histology; we advocate caution in MGP-negative cases and that specific guidelines are needed.

Idiopathic multicentric Castleman disease (iMCD)-idiopathic plasmacytic lymphadenopathy: A distinct subtype of iMCD-not otherwise specified with different clinical features and better survival.

Idiopathic multicentric Castleman disease (iMCD) is subclassified into iMCD-thrombocytopenia, anasarca, reticulin fibrosis, renal dysfunction, organomegaly (TAFRO) and iMCD-not otherwise specified (NOS) according to the Castleman Disease Collaborative Network (CDCN) consensus criteria. With a deeper understanding of iMCD, a group of patients with iMCD-NOS characterised by polyclonal hypergammaglobulinaemia, plasmacytic/mixed-type lymph node histopathology and thrombocytosis has attracted attention. This group of patients has been previously described as having idiopathic plasmacytic lymphadenopathy (IPL). Whether these patients should be excluded from the current classification system lacks sufficient evidence. This retrospective analysis of 228 patients with iMCD-NOS identified 103 (45.2%) patients with iMCD-IPL. The clinical features and outcomes of patients with iMCD-IPL and iMCD-NOS without IPL were compared. Patients with iMCD-IPL showed a significantly higher inflammatory state but longer overall survival. No significant difference in overall survival was observed between severe and non-severe patients in the iMCD-IPL group according to the CDCN severity classification. Compared with lymphoma-like treatments, multiple myeloma-like and IL-6-blocking treatment approaches in the iMCD-IPL group resulted in significantly higher response rates and longer time to the next treatment. These findings highlight the particularities of iMCD-IPL and suggest that it should be considered a new subtype of iMCD-NOS.

Prognostic Impact of Preoperative Thrombocytosis on Recurrence-Free Survival in Patients with Upper Tract Urothelial Carcinoma.

BACKGROUND: The aim of this work was to evaluate the prognostic potential of preoperative thrombocytosis for recurrence-free survival (RFS) and cancer-specific survival (CSS) among patients subjected to radical nephroureterectomy (RNU) due to UTUC. PATIENTS AND METHODS: Analytical cohort was composed of a single-center series of 405 patients treated between January 1999 and December 2020. Thrombocytosis was defined as a platelet count exceeding the threshold value of 400 × 109 per L. Along with the Kaplan-Meier survival probability, Cox proportional hazard regression models were used. RESULTS: Preoperative thrombocytosis confirmed in 71 patients (17.5%) was significantly associated with the higher pathological tumor stage, lymph node metastasis, prior bladder cancer diagnosis, and preoperative anemia. With a median post-surgical follow-up period of 33.5 months, 125 patients (30.9%) experienced disease recurrence. The recurrence rate among patients with normal platelet levels was 13.6%, compared with 22.2% in those with preoperative thrombocytosis (p < 0.03). The 5-year RFS estimates reached 36.6% in the thrombocytosis-confirmed group. Multivariate analysis implied that preoperative thrombocytosis was a significant independent prognosticator of both poor RFS (HR 2.22, 95% CI 1.14-4.31, p = 0.02) and CSS (HR 2.48, 95% CI 1.14-3.09, p = 0.01). CONCLUSIONS: Patients with a clinically significant elevation of platelet count prior to RNU were more likely to have UTUC with advanced tumor stages and lymph node metastases. Preoperative thrombocytosis was an independent predictor of RFS and CSS in patients who underwent radical nephroureterectomy. Furthermore, preoperative thrombocytosis may complement and refine UTUC clinical prediction algorithms as an independent indicator of adverse survival outcomes.

Hereditary thrombocythemia due to splicing donor site mutation of THPO in a Japanese family.

Thrombopoietin (THPO) is an essential factor for platelet production. Hereditary thrombocythemia (HT) is caused by a germline mutation of THPO, MPL, or JAK2 and is inherited in an autosomal-dominant manner. We identified a Japanese family with HT due to a point mutation of the splicing donor site of the THPO gene (THPO c.13 + 1G > A). Bone marrow biopsy showed increased megakaryocytes mimicking essential thrombocythemia. One affected family member developed chronic myeloid leukemia. We cloned the mutation and developed mutated and wild type THPO expression vectors. Molecular analysis showed that the mutation causes an exon 3 skipping transcript of THPO that abrogates a suppressive untranslated upstream open reading frame. Although the transcript levels of THPO mRNA were comparable, mutated transcripts were more efficiently translated and THPO protein expression was significantly higher than that of the wild type.

The personal impact of living with a myeloproliferative neoplasm.

OBJECTIVE: The aim of this study is to gain insight into the physical, psychological and social impact of having a myeloproliferative neoplasm (MPN), a rare type of cancer with an often chronic course. METHODS: An online survey was conducted among 455 Dutch MPN patients (62.7% female, age M 63) to explore the impact of the disease by measuring the MPN symptom burden (MPN-SAF TSS) and quality of life (QoL) (EORTC QLQ-C30) and its subscales within a hierarchical QoL model. We examined differences in MPN symptom burden and QoL in relation to sociodemographic and disease-related factors. Hierarchical regression analysis was used to explain variances in QoL. RESULTS: Most patients (97%) experienced MPN-related health complaints, with a significantly higher MPN symptom burden in women (M 31.50) compared to men (M 24.10). Regarding to fatigue and cognitive functioning MPN patients suffered more compared to a reference group of other cancers. MPN subtype or type of treatment did not show significant differences in MPN symptom burden or QoL. However, experiencing side effects, complications or comorbidities significantly negatively affected MPN symptom burden and QoL. 48.8% of patients reported that MPN affected their ability to work. The explained variance in overall QoL was 58%, most importantly by disease progression, comorbidities, MPN symptom burden and role, emotional and social functioning. CONCLUSION: This study revealed that having an MPN has a negative impact on several domains of QoL. Symptom assessment and support should be included in the healthcare management of MPN patients.

Preoperative platelet count as an independent predictor of long-term outcomes among patients undergoing resection for intrahepatic cholangiocarcinoma.

BACKGROUND AND OBJECTIVES: An elevated platelet count may reflect neoplastic and inflammatory states, with cytokine-driven overproduction of platelets. The objective of this study was to evaluate the prognostic utility of high platelet count among patients undergoing curative-intent liver surgery for intrahepatic cholangiocarcinoma (ICC). METHODS: An international, multi-institutional cohort was used to identify patients undergoing curative-intent liver resection for ICC (2000-2020). A high platelet count was defined as platelets >300 *109/L. The relationship between preoperative platelet count, cancer-specific survival (CSS), and overall survival (OS) was examined. RESULTS: Among 825 patients undergoing curative-intent resection for ICC, 139 had a high platelet count, which correlated with multifocal disease, lymph nodes metastasis, poor to undifferentiated grade, and microvascular invasion. Patients with high platelet counts had worse 5-year (35.8% vs. 46.7%, p = 0.009) CSS and OS (24.8% vs. 39.8%, p < 0.001), relative to patients with a low platelet count. After controlling for relevant clinicopathologic factors, high platelet count remained an adverse independent predictor of CSS (HR = 1.46, 95% CI 1.02-2.09) and OS (HR = 1.59, 95% CI 1.14-2.22). CONCLUSIONS: High platelet count was associated with worse tumor characteristics and poor long-term CSS and OS. Platelet count represents a readily-available laboratory value that may preoperatively improve risk-stratification of patients undergoing curative-intent liver resection for ICC.

Research progress of malignant peritoneal mesothelioma with paraneoplastic syndrome: A review.

Malignant peritoneal mesothelioma (MPM) is a rare and invasive tumor, and some patients will develop paraneoplastic syndrome (PS) during the course of the disease. This review summarizes PS associated with MPM, focusing on the clinical characteristics and treatment progress in hematological, endocrine, rheumatic, neurological, urinary, and other systems to decrease missed diagnosis and misdiagnosis, help early diagnosis and prompt treatment, and provide guidance for the clinical decision-making of this kind of patients.

Etiology and clinical course of severe and extreme thrombocytosis in children: a retrospective single-center study.

The aim of this study was to describe the etiology and clinical course in children with severe thrombocytosis (ST, platelet counts > 900 × 109/L) and extreme thrombocytosis (ET, platelet counts > 1000 × 109/L) in a tertiary pediatric hospital. Patients aged 0-18 years with platelet counts over 900 × 109/L who were admitted to our hospital were analyzed. Thrombocytosis was defined as a platelet count exceeding 450 × 109/L. Thrombosis was diagnosed based on computed tomography scans or ultrasound findings. Potential factors associated with the development of extreme thrombocytosis were identified using logistic regression models. Only one (0.8%) out of the 120 patients identified with ST (n = 61) and ET (n = 59) had primary thrombocytosis. The most common underlying condition was congenital heart disease (26.7%), followed by Kawasaki disease (16.7%). With the exception of the hemoglobin level, no major differences were found for the baseline characteristics between the ST and ET groups. A lower hemoglobin level (< 10.0 g/dL) at the onset of thrombocytosis was identified as a predictor for ET development (adjusted odds ratio 2.73, 95% confidence interval 1.18-6.28). Overall, 56 of 120 (46.7%) patients received aspirin therapy. Venous thrombosis occurred in one (0.8%) patient. CONCLUSIONS: We found a low proportion of primary thrombocytosis and a low incidence of thrombosis in children with ST and ET. Our results suggest that pediatric ST and ET may share common characteristics and may have features that are distinct from those in adults. WHAT IS KNOWN: • Secondary thrombocytosis is a frequent finding in children. • Adult extreme thrombocytosis has been found to be associated with primary thrombocytosis. WHAT IS NEW: • There were no major differences in the baseline characteristics between children with severe and extreme thrombocytosis. • The incidence of thrombosis was markedly low in both severe and extreme thrombocytosis groups.

Extreme Reactive Thrombocytosis Caused by Obstructive Nephrolithiasis and Pyelonephritis.

Platelet counts in reactive thrombocytosis rarely exceed 1000 × 109/L. We present the case of a male patient, aged 80 years, with quiescent rheumatoid arthritis who was found to have a platelet count of 1011 × 109/L on routine laboratory testing. The patient was initially asymptomatic but developed leukocytosis to 23.1 × 109/L on hospital day 2. Diagnostic work-up revealed obstructive nephrolithiasis and pyelonephritis, and the thrombocytosis and leukocytosis gradually resolved with empiric antibiotic treatment and ureteral stent placement. Tests for myeloproliferative disorders, including JAK-2V617F mutation, BCR-ABL for chronic myeloid leukemia and acute lymphocytic leukemia, and myeloproliferative neoplasms (MPL/CALR), were negative. Physicians should be aware that in rare cases reactive thrombocytosis can exceed 1000 × 109/L, and that markedly elevated platelet counts in the setting of urinary tract infections may be an early sign of obstructive uropathy.

Risk factors and prognosis of malignant peritoneal mesothelioma with paraneoplastic syndrome.

BACKGROUND: Malignant peritoneal mesothelioma (MPM) is a rare and highly aggressive tumor. Its clinical manifestations are diverse, and the symptoms are not specific. Some patients will develop paraneoplastic syndrome (PS) during the disease course. This study aims to analyze the risk factors of PS in patients with MPM and their impacts on prognosis. METHODS: The clinical data of MPM patients who underwent cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) at our center from June 2015 to May 2023 were retrospectively analyzed. MPM patients were divided into PS group and non-PS group according to the diagnostic criteria. Univariate and multivariate analyses were performed to explore the risk factors of PS in MPM patients, and to analyze the impact of PS on prognosis. RESULTS: There were 146 MPM patients in this study, including 60 patients (41.1%) with PS and 86 patients (58.9%) without PS. The highest incidence of PS was thrombocytosis (33.6%), followed by neoplastic fever (9.6%). Univariate analysis revealed 8 factors (P < 0.05) with statistically significant differences between the two groups: prior surgical scores, targeted therapy history, Karnofsky performance status score, preoperative carbohydrate antigen (CA) 125 level, vascular tumor embolus, peritoneal cancer index, completeness of cytoreduction (CC) score and intraoperative ascites. Multivariate analysis identified 3 independent factors associated with PS: preoperative CA 125 level, vascular tumor embolus, and CC score. Survival analysis demonstrated that MPM patients with PS had worse prognosis, although PS was not an independent prognostic factor. CONCLUSIONS: PS is not rare in patients with MPM, and is independently associated with preoperative CA 125 level, vascular tumor embolus and CC score. PS often indicates advanced disease and poor prognosis.

Distinctive patterns of sequential platelet counts following blunt traumatic brain injury predict outcomes.

OBJECTIVE: To determine the role of platelet counts in the context of the decision to treat patients with non-compounded, non-surgically-treated blunt traumatic brain injury (NCNS-bTBI) with anticoagulants/antiaggregants. METHODS: A retrospective analysis of 141 anticoagulants/antiaggregants-naïve patients with NCNS-bTBI. Changes in PT-INR and prolonged aPTT were examined and correlated with Marshall and Rotterdam scores, clinical and neuroradiological outcomes. RESULTS: Three groups of platelet counts were identified. Group 1 (83% of patients) had normal platelet counts (150,000-450,000 platelets/mm3) from admission to discharge. Group 2 (13%) developed transient thrombocytopenia (<150,000 platelets/mm3) 2-3 days post-trauma. Group 3 (4%) developed extreme thrombocytosis > 1,000,000/mm3 platelets 6-9 days post-trauma. Neither acute coagulopathy of trauma nor progressive hemorrhagic insults followed NCNS-bTBI. Moreover, while patients with thrombocytosis/extreme thrombocytosis presented with a worse Glasgow coma score (GCS) on admission (8.8 ± 2.9 vs. 13 ± 2, p < 0.01) and had longer hospitalization (13.5 ± 10.4 vs. 4.5 ± 2.1 days), their improvement at discharge was the highest (delta GCS, 4 ± 2.8 vs. 1.2 ± 2.1, p = 0.05). Traumatic subarachnoid hemorrhage was associated with isolated thrombocytosis and 'best improvement.' No thromboembolic or hemorrhagic complications occurred. CONCLUSION: NCNS-bTBI, thrombocytosis was correlated with better outcomes and was not associated with an increased risk for developing thromboembolism or hemorrhage, precluding the immediate need for any additional antiaggregates.

Secretory Phospholipase A2 Levels Are High in Women with Sickle Cell Disease and Menstruation-Induced Vaso-Occlusive Crises.

Menstruation-induced vaso-occlusive crisis (MIVOC) is a significant cause of morbidity in women with sickle cell disease (SCD). Secretory phospholipase A2 (sPLA2) is an inflammatory biomarker that is elevated in vaso-occlusive events such as acute chest syndrome (ACS), but its role in MIVOC is not previously studied. This study compared the serum level of sPLA2 among women with MIVOC and those without MIVOC. This is a comparative cross-sectional study. 354 women with SCD were screened for MIVOC using a structured questionnaire. sPLA2 levels were assayed using a standard ELISA while full blood counts were performed on an automated hematology analyzer. Data were analyzed using the SPSS software v26.0. Results were summarized as frequencies, percentages, and mean ± standard deviation. Variables were compared using the Student's t-test and Pearson's correlation. A p-value of <.05 was considered significant. The prevalence of MIVOC was 26.8%. Participants with MIVOC (n = 95) had significantly lower mean hemoglobin concentration (8.00 ± 2.03g/dL vs. 9.95 ± 4.15g/dL, p < .000), significantly higher mean platelets count (518.71 ± 84.58 × 109/L vs 322.21 ± 63.80 × 109/L, p < .000) and higher sPLA2 level (6.58 ± 1.94 IU vs 6.03 ± 0.42 IU, p = .008) compared to those without MIVOC (n = 95). Among participants with MIVOC, sPLA2 levels positively correlated with total white blood cell, absolute neutrophil, and lymphocyte counts. This study demonstrates that MIVOC is common among women with SCD and that the pathophysiology of MIVOC may have an inflammatory basis similar to that of ACS. The potential role of anti-inflammatory and antiplatelet agents in preventing and treating MIVOC may be explored.

Sepsis-Related Outcomes of Patients with Philadelphia-Negative Myeloproliferative Neoplasms.

We analyzed the National Inpatient Sample (NIS) database to study the sepsis-related outcomes in patients with Philadelphia negative myeloproliferative neoplasms (MPN). A total of 82,087 patients were included, most had essential thrombocytosis (83.7%), followed by polycythemia vera (13.7%), and primary myelofibrosis (2.6%). Sepsis was diagnosed in 15,789 (19.2%) patients and their mortality rate was higher than nonseptic patients (7.5% vs 1.8%; p < .001). Sepsis was the most significant risk factor of mortality (aOR, 3.84; 95% CI, 3.51-4.21), others included liver disease (aOR, 2.42; 95% CI, 2.11-2.78), pulmonary embolism (aOR, 2.26; 95% CI, 1.83-2.80), cerebrovascular disease (aOR, 2.05; 95% CI, 1.81-2.33), and myocardial infarction (aOR, 1.73; 95% CI, 1.52-1.96).

Sepsis-related outcomes of patients with Philadelphia-negative myeloproliferative neoplasms.

We analyzed the National Inpatient Sample (NIS) database to study the sepsis-related outcomes in patients with Philadelphia negative myeloproliferative neoplasms (MPN). A total of 82,087 patients were included, most had essential thrombocytosis (83.7%), followed by polycythemia vera (13.7%), and primary myelofibrosis (2.6%). Sepsis was diagnosed in 15,789 (19.2%) patients and their mortality rate was higher than non-septic patients (7.5% vs 1.8%; P<.001). Sepsis was the most significant risk factor of mortality (aOR, 3.84; 95% CI, 3.51-4.21), others included liver disease (aOR, 2.42; 95% CI, 2.11-2.78), pulmonary embolism (aOR, 2.26; 95% CI, 1.83-2.80), cerebrovascular disease (aOR, 2.05; 95% CI, 1.81-2.33), and myocardial infarction (aOR, 1.73; 95% CI, 1.52-1.96).

Erythrocytosis, thrombocytosis, and rate of recurrent thromboembolic event-A population based cohort study.

INTRODUCTION: The management to reduce risk of thromboembolic complications in polycythemia vera and essential thrombocythemia are well established, but for other conditions with elevated hemoglobin, hematocrit, or platelets there are no consensus regarding treatment and follow up. AIMS: To assess frequency of elevated blood values in patients with thromboembolic event, how many of these should be investigated further regarding myeloproliferative neoplasm and if the risk of recurrent event is depending on underlying condition. METHODS: Retrospective cohort study of 3931 adult patients in the county of Norrbotten, Sweden, with thromboembolism during 2017 and 2018. RESULTS: Of the 3931 patients, 1195 had either elevated Hb, HCT, or platelets fulfilling the 2016 revised WHO criteria for PV and ET, and out of these 411 should be evaluated regarding underlying myeloproliferative neoplasms. Unexplained thrombocytosis and secondary erythrocytosis were associated with the highest rate of recurrent event as well as the most inferior restricted mean survival time. CONCLUSION: Elevated blood values are common in patients with thromboembolic event and the high risk of recurrent event and inferior restricted mean survival time in patients with unexplained thrombocytosis and secondary erythrocytosis implicates the importance of finding and managing the underlying condition.

Clinical significance of reactive thrombocytosis in the course of acute pancreatitis.

BACKGROUND: Reactive thrombocytosis occurs secondary to systemic infections, inflammatory, and other conditions. The relationship between thrombocytosis and acute pancreatitis (AP) in inflammatory diseases is uncertain. This study aimed to evaluate the clinical significance of thrombocytosis in AP patients during hospitalization. METHODS: Subjects within 48 h of AP onset were consecutively enrolled over 6 years. Platelet counts of ≥ 450,000/µL were defined as thrombocytosis, < 100,000/µL as thrombocytopenia, and other counts as normal. We compared clinical characteristics, including the rate of severe AP (SAP) assessed by the Japanese Severity Score; blood markers, including hematologic and inflammatory factors and pancreatic enzymes during hospitalization; and pancreatic complications and outcomes in the three groups. RESULTS: A total of 108 patients were enrolled. Although, SAP was more common in patients with thrombocytosis and thrombocytopenia (87.9% and 100%, respectively), the differences in lymphocytes and C-reactive protein, lactase dehydrogenase, and antithrombin levels, which are factors of the systemic inflammatory response, and the mean platelet volume, an indicator of platelet activation, were observed among patients with thrombocytosis and thrombocytopenia during hospitalization. Regarding pancreatic complications and outcomes, patients with thrombocytosis and thrombocytopenia had higher acute necrotic collection (ANC), pancreatic necrosis, intestinal paralysis, respiratory dysfunction, and pancreatic-related infection levels than patients with normal platelet levels. The relationship between pancreatic complications and thrombocytosis was assessed by multivariate logistic regression; the odds ratios for development of ANC, pancreatic necrosis and pancreatic-related infections were 7.360, 3.735 and 9.815, respectively. CONCLUSIONS: Thrombocytosis during hospitalization for AP suggests development of local pancreatic complications and pancreatic-related infections.

Clonal Megakaryocyte Dysplasia with Isolated Thrombocytosis Is a Distinct Myeloproliferative Neoplasm Phenotype.

INTRODUCTION: About 15% of people with a myeloproliferative neoplasm (MPN) are identified as MPN, unclassifiable using the 2016 WHO classification. METHODS: We tested whether persons with platelet concentration ≥450 × 10E+9/L, bone marrow megakaryocyte morphology typical of prefibrotic/early myelofibrosis (pre-MF), and no minor criteria of pre-MF should be classified as a distinct MPN subtype, clonal megakaryocyte dysplasia with isolated thrombocytosis (CMD-IT). RESULTS: 139 subjects meet these criteria who we compared with primary myelofibrosis (PMF) including 402 with pre-MF and 521 with overt myelofibrosis. CMD-IT subjects were more likely female and younger. They had lower frequencies of JAK2V617F compared with persons with PMF (55% vs. 70%; p < 0.001) and higher frequencies of CALR mutations (37% vs. 17%; p < 0.001). They also had lower frequency of variations associated with JAK2V617F susceptibility, JAK2 46/1 (35% vs. 47%; p = 0.021), and VEGFA rs3025039 (12% vs. 17%; p = 0.030). Subjects with CMD-IT had lower incidences of thrombotic events compared with those with pre-MF (9.7% vs. 26%; p < 0.001) and longer survival (median, not reached vs. 23 years; HR = 0.34 (0.10, 0.30); p < 0.001). CONCLUSION: Our data indicate CMD-IT is a distinct MPN subtype and should be included in the classification of myeloid neoplasms.