ADAMTS13, von Willebrand Factor, Platelet Microparticles, Factor VIII, and Impact of Somatic Mutations in the Pathogenesis of Splanchnic Vein Thrombosis Associated with BCR-ABL-Negative Myeloproliferative Neoplasms.

BACKGROUND: Myeloproliferative neoplasms (MPNs) are often associated with splanchnic vein thrombosis (SVT). Not all the factors involved in the thrombotic tendency are currently known. OBJECTIVES: This study aims to evaluate a possible association between ADAMTS13, von Willebrand factor (VWF), platelet microvesicles (MV), and factor VIII activity (FVIII:C) with thrombotic events in MPN patients. MATERIALS AND METHODS: In total, 36 consecutive MPN patients with SVT were enrolled. The MPNs were diagnosed based on clinical characteristics and one or more gene mutations among JAK-2, CALR, and MPL. As controls, 50 randomly selected patients with MPN without thrombosis, 50 patients with deep vein thrombosis without MPNs, and 50 healthy blood donors were evaluated. Complete blood count, ADAMTS13, VWF, MV, and FVIII:C in plasma were measured in all the subjects. RESULTS: The JAK-2 mutation was found in 94% of the patients with SVT, but none were triple-negative for genetic mutations (JAK2 V617F, CALR, MPL, and exon 12). Compared to the normal subjects, in all the MPN patients (with or without SVT), the levels of ADAMTS13 were found to be significantly lower (p < 0.001) and the MV concentrations were significantly higher (p < 0.001). Among the MPN patients, the VWF and FVIII:C levels were significantly higher in the patients with SVT than those without thrombosis (p = 0.007 and p = 0.04, respectively). Splenomegaly was present in 78% of MPN patients with SVT and in 30% of those without SVT (p < 0.001). The ADAMTS13/VWF ratio was reduced in all the patients, but not in the healthy blood donors (p < 0.001). CONCLUSIONS: The significant increase in circulating MV, VWF, and FVIII:C in the MPN patients and in the patients with thrombosis supports the role of endothelium damage in promoting thrombotic events. In particular, a significant increase in VWF and FVIII:C levels was found in the MPN patients with SVT.

A Novel Morphological Parameter Predicting Fibrotic Evolution in Myeloproliferative Neoplasms: New Evidence and Molecular Insights.

Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) represent a group of hematological disorders that are traditionally considered as indistinct slow progressing conditions; still, a subset of cases shows a rapid evolution towards myelofibrotic bone marrow failure. Specific abnormalities in the megakaryocyte lineage seem to play a central role in this evolution, especially in the bone marrow fibrosis but also in the induction of myeloproliferation. In this review, we analyze the current knowledge of prognostic factors of MPNs related to their evolution to myelofibrotic bone marrow failure. Moreover, we focused the role of the megakaryocytic lineage in the various stages of MPNs, with updated examples of MPNs in vitro and in vivo models and new therapeutic implications.

Pediatric myelofibrosis: WHO 2024 update on myeloproliferative neoplasms calling?

OBJECTIVES: Pediatric myelofibrosis is a rare entity with the largest reported series of 19 cases. We describe here the clinicopathological spectrum and outcomes of 15 cases of pediatric myelofibrosis. METHODS: Case files of myelofibrosis of patients less than 18 years were retrieved from January 2016 to January 2019, and patients with idiopathic myelofibrosis after exhaustive work-up were studied. Their clinicopathological profiles were studied and then followed up for resolution and malignant transformation. RESULTS: Of the 15 cases of idiopathic myelofibrosis, transfusion-dependent anemia (14/15) was most common presentation. Only one patient showed leukoerythroblastosis with dacryocytes. Myeloid hyperplasia was seen in 13 of 15 patients and megakaryocytic hyperplasia in 10 patients. Dysmegakaryopoiesis was seen in 8 of 15 patients, and only three had small loose megakaryocytic clustering. None showed hyperchromatic megakaryocytes, intrasinusoidal hematopoiesis, or osteosclerosis. One patient with trisomy 8 tested positive for JAK2V617F. Bone marrow biopsy was hypercellular in 13, and 8 had world health organization (WHO) MF-3 fibrosis. None of the patients developed malignancy, one had spontaneous resolution, and one patient required allogenic stem cell transplant. CONCLUSIONS: Pediatric myelofibrosis is a distinct entity from primary myelofibrosis in adults and merits mention in the WHO manual as a distinct entity.

Phenotypic characterization of malignant progenitor cells in patients with idiopathic myelofibrosis.

OBJECTIVE/BACKGROUND: Idiopathic myelofibrosis (IM) is a clonal hematological malignancy originating from pluripotent hematopoietic stem cells (HSC). HSC are very rare potent cells that reside in the bone marrow (BM) and at a lower level in peripheral blood (PB). Previous studies showed that IM PB CD34+ cells contain not only BM repopulating cells belonging to the malignant clone but also residual normal HSC. METHODS: In the current study, we separated the subpopulations of IM PB CD34+ cells using IL-3Rα/CD123 labeling and further characterized them by genetic and functional analyses. RESULTS: We differentiated IM PB CD34+ cells into three subpopulations (IL-3Rαhigh, IL-3Rαlow, and IL-3Rαnegative). IL-3Rαhigh CD34+ cell subgroup represents a small population in IM PB CD34+ cells which was not seen in normal G-CSF mobilized CD34+ cells. IM IL-3Rαhigh CD34+ cells contained significant higher percentage of cells bearing marker chromosome detected by fluorescence in situ hybridization (FISH) analysis. In the absence of growth factors, IM IL-3Rαhigh CD34+ cells exhibited abnormal colony forming ability and carried greater percentage of JAK2V617F mutant allele compared with IL-3Rαlow and IL-3Rαnegative CD34+ cells. CONCLUSION: These data indicate that IL-3Rαhigh CD34+ cells from IM enriched for the malignant progenitor cells and IL-3Rα/CD123 may be a potential biomarker and therapeutic target for IM. Our findings will be further validated in future studies with a larger sample size and serial transplant in murine models.

Laparoscopic "double-port" splenectomy. A new minimally-invasive option in a giant spleen.

INTRODUCTION: In case of massive splenomegaly, laparoscopic splenectomy (LS) becomes challenging, uncomfortable and risky both for the surgeon and for the patient. As a consequence of ongoing research to obtain efficient and cheaper "scarless surgery", single-port technique and hand-assisted devices were developed and improved in this field. PRESENTATION OF CASE: We present the clinical case of a patient affected by idiopathic myelofibrosis (MF) and splenomegaly who was admitted to our Department to perform a splenectomy for a suspected 5-cm splenic lesion. DISCUSSION: The splenic longitudinal diameter measured 26 cm. The patient underwent splenectomy by laparoscopy, combining a single-port access and a gel-port device. The operation was completed laparoscopically. The operating time was 220 min and the estimate blood loss was 100 ml. The patient was discharged at 11 post-operative day in overall good conditions. Upon pathological analysis the splenic lesion was a localization of diffuse large B-cell Lymphoma in the context of MF. CONCLUSION: this novel "hybrid technique" of splenectomy, combining the advantages of reduced number of abdominal incisions of the single-port technique to those of the hand assistance, is feasible in massive splenomegaly with good results. Furthermore, the use of the sovrapubic retrieval incision as the introduction site for the hand assisted device is convincing, since it's useful for both tasks. Further studies with large casuistries are necessary to confirm the effectiveness of the technique.

Pulmonary Langerhans cell histiocytosis, acute myeloid leukemia, and myelofibrosis in a large family and review of the literature.

BACKGROUND: There is mounting evidence that Langerhans cell histiocytosis (LCH) and acute myeloid leukemia (AML) are hematopoietic neoplasms that arise from the same myeloid precursor cell. In addition, studies suggest a relationship between LCH and primary idiopathic myelofibrosis (MF). Furthermore familial LCH, AML, and MF have each been reported. METHODS: We examined more than 750 pedigrees of familial hematologic malignancies for evidence of familial LCH, AML, and/or MF and identified one family with all three neoplasms, which is presented here. FINDINGS: In four generations of this large family there are five cases of AML in three generations, two cases of LCH in two generations and three cases of MF in two generations. Anticipation of -18 and -6 years was present in the patients with MF, and -8 years in the patients with LCH. Anticipation was also identified between one AML patient pair in generations III and IV (-18 years) and three patients with AML in generations II, III, and IV (-5 years and -10 years). INTERPRETATION: This is the first report of familial LCH, AML, and MF in one family. The pedigree suggests a common basis for these entities, which is further suggested by the presence of anticipation in the pedigree.

Clinico-Pathological Profile And Outcomes Of Patients With Polycythaemia Vera, Essential Thrombocythaemia And Idiopathic Myelofibrosis: A Tertiary Care Center Experience From Southern Pakistan.

BACKGROUND: The "Philadelphia Negative Classic Myeloproliferative Neoplasms" include polycythaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IMF). These three disorders share several clinical and laboratory features including JAK2 V617F mutation. Our objectives were to determine the clinico-pathological profile and outcomes of Pakistani patients with polycythaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IMF) in order to have an insight regarding behaviour of these conditions. METHODS: A retrospective analysis of all the cases of PV, ET and IMF diagnosed at our institute from January 1995 to December 2013 was performed. Age, gender, clinical presentation, laboratory investigations, treatment provided and duration of follow-up were included for analysis. Appropriate statistics were utilized for calculation of data. RESULTS: A total of 58 patients were diagnosed as PV, ET or IMF during the study period. Male to female ratio was 1.1:1. Forty five percent (n=27) patients came to medical attention due to abnormal laboratory results, 3 had cerebrovascular events, 3 had pruritus, and 1 patient each with gangrene and Budd-Chiari syndrome. Haemorrhage was not seen in any patient. Sixty percent (n=35) patients were treated with phlebotomy, hydroxyurea and aspirin alone or in combination. None of the patients transformed to myelofibrosis (MF) or myelodysplasia (MDS) during the mean (±SD) follow-up period of 57.2±50 months. One patient with ET transformed to acute myeloid leukaemia 9 years after the diagnosis. CONCLUSIONS: This study demonstrated a relatively more benign form of PV, ET and IMF with lesser frequency of symptoms, good response to treatment and less likelihood of transformation to MF, MDS or AML.

Prevalence of the frequency of JAK2 (V617F) mutation in different myeloproliferative disorders in Egyptian patients.

BACKGROUND AND OBJECTIVES: Detection of chromosomal abnormalities in myeloproliferative disorders is important for proper diagnosis of these disorders. This study has investigated the presence of JAK2 mutation (V617F) in Egyptian patients with myeloproliferative disorders referred to National Cancer institute, Cairo University. METHODS: The study involved 110 cases of Philadelphia negative Myeloproliferative diseases (MPDs), 70 cases with Polycythemia Vera (PV), 24 cases with Essential Thrombocytosis (ET) and 16 cases with Idiopathic Myelofibrosis (IMF) and 20 cases as a control group which represented as; (10 cases with secondary erythrocytosis, 1 case with reactive thrombocytosis, 4 cases as normal control and 5 as Philadelphia positive Chronic Myeloid Leukemia cases), they were collected from National Cancer Institute (NCI) over 3 years. We used ARMS technique for mutation detection. RESULTS: The frequency of the V617F JAK2 mutation was highest in patients with PV where 56 out of 70 cases (80%) carried the mutation, followed by ET with 6 of 24 (25) and IMF with 2 of 16 (12.5%) . None of the cases with secondary Erythrocytosis, reactive thrombocytosis, the normal controls or Philadelphia positive CML cases carried the mutation. CONCLUSIONS: Our results are concordant with international published results for detection of this mutation. It is unequivocal now that V617F is met in many MPDs especially PRV. Finding this mutation in those patients is thought to have a big impact on the diagnosis and treatment of these disorders.

An unusual long-term outcome of a child with primary myelofibrosis harboring a JAK2 mutation.

We report an extremely rare case of a female child who presented the onset of primary myelofibrosis (PMF) harboring JAK2 (Janus Kinase 2 gene) mutation (JAK2V617F) when she was 15 months old. She was monitored over 25 years, a period in which she was treated with spleen radiotherapy and recombinant interferon α. She also underwent splenectomy when she was 13 years old, due to massive splenomegaly, anemia and various infection disease episodes. The longstanding evolution of the patient enabled us to verify that there were no complications related to post-splenectomy events and/or blast transformation. To the best of our knowledge, this is the first reported case of severe PMF with JAK2 mutation in a child. We provide evidence that a better quality of life and long survival in pediatric PMF may be provided by splenectomy.

Translocation t(3;12)(q26;q21) in JAK2(V617F) Point Mutation Negative Chronic Idiopathic Myelofibrosis: A Case Report.

The myeloproliferative diseases (MPDs) or myelo-proliferative neoplasms (MPNs) are a group of diseases of the bone marrow in which excess cells are produced. Chronic idiopathic myelofibrosis (CIMF) is a stem cell defect characterized by splenomegaly with multiorgan extramedullary hematopoiesis, immature peripheral blood granulocytes and erythrocytes and progressive bone marrow fibrosis. The most common chromosomal abnormalities seen in CIMF patients include numerical changes of chromosomes 7, 8 and 9, and structural changes of 1q, 5q, 13q and 20q. At least 75.0% of patients with bone marrow abnormalities have one or more of these chromosomal anomalies. Detection of the Janus kinase 2 (JAK2) mutation may be a potential major breakthrough for understanding the pathobiology of MPNs, and is an essential part of the diagnostic algorithm. In this study, we describe a JAK2(V617F) mutation negative CIMF patient who has the chromosomal translocation t(3;12)(q26;q21) in her karyotype.

Chronic Childhood Idiopathic Myelofibrosis in Down's Syndrome: A Case Report.

Idiopathic myelofibrosis a disease of elderly is rarely seen in children. A case of chronic idiopathic myelofibrosis in an 8 year old boy with Down's syndrome is reported here, who presented with progressive pallor and hepatosplenomegaly. Peripheral blood examination revealed pancytopenia, macrocytic anemia and tear drop cells. No blasts were found. Bone marrow aspirate yielded a dry tap and trephine biopsy showed marrow fibrosis with osteosclerosis. Focally megakaryocytes were increased in number with atypical morphology. No blasts were seen. Review of literature revealed 47 reported cases of childhood idiopathic myelofibrosis. Six cases were associated with Down's syndrome and only 3 of them had features of chronic idiopathic myelofibrosis without evidence of acute megakaryoblastic leukaemia.

Portal hypertension and ascites in extramedullary hematopoiesis.

Myeloproliferative diseases (MPD) are clonal stem cell disorders which mainly include polycythemia vera (PV), essential thrombocythemia (ET), and idiopathic myelofibrosis (IMF). They are characterized by leucocytosis, thrombocytosis, erythrocytosis, splenomegaly, and bone marrow hypercellularity. This might also result in extramedullary hematopoiesis. Abdominal manifestation has been recognized as a feature of these disorders. Splenomegaly and hepatomegaly are fairly common as opposed to ascites which is rare. The MPDs mainly affect the hepatic circulatory systems. The common hepatic manifestations are Budd-Chiari syndrome (BCS), portal vein thrombosis (PVT), and nodular regenerative hyperplasia. A few other features seen in MPDs are caused by extramedullary hematopoiesis, increased hepatic blood flow, and secondary hemosiderosis from multiple blood transfusions. Portal hypertension is found in up to 7% of patients. We report a case of portal hypertension with ascites in a patient with extramedullary hematopoiesis treated with transjugular intrahepatic portocaval shunt (TIPS).

Cutaneous Extramedullary Hematopoiesis in Idiopathic Myelofibrosis / 대한피부과학회지

Extramedullary hematopoiesis is commonly seen in the liver, spleen and lymph nodes, but cutaneous extramedullary hematopoiesis (CEH) is very rare. CEH affects mainly children with intrauterine viral or hematologic disorders and rare manifestation of chronic myeloproliferative processes in adults. Idiopathic myelofibrosis (IM) is a chronic myeloproliferative disorder and some cases of IM have extramedullary hematopoiesis. IM is characterized by the proliferation of the endothelial cells and fibroblasts in the bone marrow, resulting in disruption of bone marrow, with subsequent migration and proliferation of the hematopoietic stem cells in other organs. We report a very rare case of cutaneous extramedullary hematopoiesis in a 74-year-old male with IM.

Tratamiento de la mielofibrosis idiopática crónica con bajas dosis de talidomida. Comunicación de 2 casos / Treatment of chronic idiopathic myelofibrosis with talidomide low doses: Report of 2 cases

La mielofibrosis idiopática crónica (MIC), también conocida como metaplasia mieloide agnogénica, mielofibrosis primaria, mieloesclerosis con metaplasia mieloide, y mielofibrosis idiopática, se caracteriza por esplenomegalia, hematopoyesis extramedular, anemia progresiva, reacción leucoeritroblástica, hematíes en lágrimas en sangre periférica y fibrosis en médula ósea. Se han obtenido beneficios modestos con las terapias para la anemia (eritropoyetina y andrógenos) o la esplenomegalia (hidroxiurea, interferón-alfa). Ninguno de estos regímenes confiere un beneficio de supervivencia o cambio demostrable en la fibrosis intramedular. La ausencia de tratamiento eficaz para la enfermedad ha llevado al estudio de sus mecanismos patogénicos y el uso de nuevas alternativas terapéuticas. Se describen 2 pacientes con diagnóstico de MIC de 9 y 5 años de evolución que debido a los altos requerimientos transfusionales y la gran esplenomegalia, se les administró tratamiento con talidomida y prednisona. El tratamiento combinado logró aumento de las cifras de hemoglobina y de los conteos de plaquetas y una reducción y eliminacin de los requerimientos transfusionales

Chronic idiopathic myelofibrosis (CIM) also known as agnogenic myeloid metaplasia, primary myelosclerosis with myeloid metaplasia and idiopathic myelofibrosis is characterized by splenomegalia, extramedullary hematopoiesis, progressive anemia, leukoerythroblastosis reaction, tears white cells in peripheral blood and bone marrow fibrosis. There have been modest benefits with anemia therapies (erythropoietin and androgens) or the splenomegalia (hydroyurea, alpha-interferon). Neither of these regimes confers survival benefit or a demonstrable change in extramedullary fibrosis. The lack of an effectiveness treatment for this disease has leads us to study its pathogenic mechanisms and the use of new therapeutical alternatives. Two cases are described diagnosed with CIM with a course of 9 and 5 years and due to the high transfusion requirements and a significant splenomegalia it was necessary to administer a treatment with thalidomide and prednisone. Combination treatment achieved an increase in hemoglobin figures and of platelet counts and a decrease and elimination of transfusion requirements

A mutação JAK2 V617F e as síndromes mieloproliferativas / JAK2 V617F mutation and the myeloproliferative disorders

Síndromes mieloproliferativas (SMPs) são doenças hematopoéticas de origem clonal que apresentam amplificação de uma ou mais linhagens mielóides. Policitemia vera (PV), trombocitemia essencial (TE), mielofibrose idiopática (MF) e leucemia mielóide crônica (LMC) são consideradas SMPs clássicas e apresentam características clínicas e biológicas comuns. Ao contrário de LMC, cuja etiologia está relacionada à proteína constitutivamente ativa Bcr-Abl, o mecanismo molecular de PV, TE e MF permaneceu por muito tempo desconhecido. Esta revisão se foca na recente descoberta da mutação JAK2 V617F em pacientes com PV, TE e MF, sua relação com o fenótipo mieloproliferativo e implicações na abordagem clínica de pacientes.

Myeloproliferative disorders are clonal hematopoietic diseases that are characterized by the amplification of one or more myeloid lineages. Polycythemia vera, essential thrombocythemia, idiopathic myelofibrosis and chronic myeloid leukemia are considered classic myeloproliferative disorders and share common clinical and biological features. While the genetic basis of chronic myeloid leukemia is shown to be the constitutive active protein BCR-ABL, the main molecular lesions in polycythemia vera, essential thrombocythemia and idiopathic myelofibrosis remain unknown. This review focuses on the recent discovery of the JAK2 V617F mutation, its relationship to the myeloproliferative phenotype and implications in the clinical approach of patients.

Diagnostic Usefulness of the Janus Kinase 2 Mutation in non BCR/ABL Myeloproliferative Disorders

BACKGROUND: We investigated the Janus kinase 2 (JAK2) mutation and its diagnostic value in patients suffering with non BCR/ABL myeloproliferative diseases (nMPD) or other reactive conditions. METHODS: We reviewed the clinical records of 83 patients who underwent bone marrow (BM) examinations with suspect of nMPD. The diagnoses of nMPD were made based on the WHO criteria since 2001 and the PVSG criteria before 2001. The JAK2 mutation was examined by PCR in 54 patients whose BM samples were available. RESULTS: The JAK2 mutation was detected in 25 patients (46%); 12 of 26 patients with essential thrombocythemia (ET), 9 of 12 patients with polycyhtemia vera (PV), one of 7 patients with chronic idiopathic myelofibrosis (CIM) and one patient with unclassifiable MPD. Additionally, JAK2 mutation was detected in each one patient with secondary polycythemia and reactive thrombocytosis. These two patients and two other patients among the JAK2 mutated ET did not meet the WHO PV criteria due to their initial low hemoglobin levels. These patients had liver cirrhosis and hypersplenism due to Budd-Chiari syndrome (1), gastrointestinal bleeding (1) or the initial hemoglobin level was slightly below the level as provided by the criteria, but the level showed a rising pattern despite cytoreductive therapy (2). With the results of the JAK2 mutation available, 4 patients' disease could be re-diagnosed as PV. Finally, the positive rate of the JAK2 mutation was 81% in PV, 48% in ET and 14% in CIM. The presence of JAK2 mutation closely correlated with PV (p=0.001), leukocytosis (p=0.001) and an increased cellularity of BM (p=0.024). CONCLUSIONS: The JAK2 mutation may help differentiate nMPD from secondary cytosis. Therefore, it should be incorporated into the guidelines for the nMPD work-up for making a more accurate diagnosis and administering proper treatment.

A Novel Jumping Translocation of 12q21 in a Patient with Chronic Idiopathic Myelofibrosis

Jumping translocation (JT) has been defined as the translocation involving one donor chromosome and multiple recipient chromosomes in different cell lines in the same patient. This is rarely observed in various hematologic malignancies. Chronic idiopathic myelofibrosis (CIMF) is considered to be a clonal hematopoietic stem cell disorder, and clonal cytogenetic abnormalities have been reported to occur in about 30~60% of patients. We report here on a case of CIMF with JT involving 12q21; t(5;12)(q13;q21) and t(12;12)(p13;q21) as the sole aberration. A pathogenetic relation between CIMF and the 12q rearrangement has been suggested in the literature, but neither the JT in CIMF nor the JT of 12q21 has been reported on. This is the first report of JT involving 12q21 in a patient with CIMF (ED note: nice writing).

Occurence of 17p Deletion with Blast Transformation in Idiopathic Myelofibrosis Treated with Hydroxyurea / 대한혈액학회지

The recently described '17p deletion syndrome' is a clonal hematologic disease which has characteristic dysgranulopoietic features, such as pseudo-Pelger-Huet hypogranulation and small vacuoles in neutrophils and is strongly associated with p53 mutation. The cases with 17p deletion are seen in 3~4% of myelodysplastic syndrome and acute myelogenous leukemia and about 30% of them are therapy-related. Hydroxyurea, which is considered to have relatively low leukemogenic potential, has therefore been widely used in chronic myeloproliferative disease. But the recent study has found that hydroxyurea administration is a considerable risk for later leukemic transformation and is closely associated with development of 17p deletion. We report one case of idiopathic myelofibrosis which developed 17p deletion with blast increment after hydroxyurea therapy for 3 years.

Two Cases of Myelofibrosis Mimicking Malignant Lymphoma in Computed Tomography of Abdomen: A Case of Autoimmune Myelofibrosis associated with Systemic Lupus Erythematosus Showing Extensive Lymphadenopathy and A Case of Chronic Idiopathic Myelofibrosis wit / 대한진단검사의학회지

Myelofibrosis results from stimulation of bone marrow stromal fibroblasts by fibrogenic cytokines elaborated by neoplastic or reactive cells in the marrow. Chronic idiopathic myelofibrosis should be differentiated from secondary myelofibrosis resulting from bone marrow involvement of malignant lymphoma because these diseases have different therapeutic strategies. Myelofibrosis in systemic lupus erythematosus is an uncommon but well-recognized complication, and identifying an autoimmune myelofibrosis is important in diagnosing this benign cause of myelofibrosis. We report two cases of myelofibrosis presenting the clinical and radiologic findings that mimicked malignant lymphoma -a case of autoimmune myelofibrosis associated with systemic lupus erythematosus showing extensive lymphadenopathy and a case of chronic idiopathic myelofibrosis with focal intrasplenic extramedullary hematopoiesis- and discuss the importance of the clinical information and radiologic findings for the pathologic diagnosis of myelofibrosis.

Pathogenesis of Idiopathic Myelofibrosis: A Review.

During the last two decades, important progress has been made in the understanding of the nature and pathogenesis of idiopathic myelofibrosis. The characteristic extracellular matrix is composed of a variety of interstitial and basement membrane glycoproteins, including collagen types I, III, IV, V and VI, fibronectin, vitronectin, laminin and tenascin, and a marked neovascularisation. In contrast to the clonal haematopoiesis, the increased stromal tissue is a reactive, or secondary phenomenon, resulting from the inappropriate release of megakaryocyte/platelet-derived growth factors, including PDGF, TGF-ß, bFGF and calmodulin. Recent cytogenetic studies have highlighted three chromosomal abnormalities, namely del(13q), del(20q) and partial trisomy 1q, that account for 70% of all abnormalities at diagnosis, and suggests that in many patients gene loss and/or inactivation may be an important pathogenetic mechanism.