Liver dysfunction following splenectomy in idiopathic myelofibrosis: a study of 10 patients

Treatment of Myelofibrosis: A Moving Target

Myelofibrosis (MF) is a myeloproliferative neoplasm that presents either as a primary disease or evolves secondarily from polycythemia vera or essential thrombocythemia to post-polycythemia vera MF or post-essential thrombocythemia MF, respectively. Myelofibrosis is characterized by stem cell-derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis, constitutional symptoms, cachexia, leukemic progression, and shortened survival. Therapeutic options for patients with MF have been limited to the use of cytoreductive agents, predominantly hydroxyurea; splenectomy and splenic irradiation for treatment of splenomegaly; and management of anemia with transfusions, erythropoiesis-stimulating agents, androgens, and immunomodulatory agents along with steroids. The only curative option is allogeneic stem cell transplantation (ASCT), which is associated with high morbidity and mortality risks. Recently, JAK (Janus kinase) inhibitor therapies have become available and proven to be palliative in primary MF patients with hydroxyurea-refractory splenomegaly and severe constitutional symptoms. The purpose of this article is to review the clinical features of MF; discuss different treatment strategies, including ASCT; and discuss the potential danger and benefit of using JAK inhibitors prior to ASCT.

Diagnosis, prevention, and management of bleeding episodes in Philadelphia-negative myeloproliferative neoplasms: recommendations by the Hemostasis Working Party of the German Society of Hematology and Medical Oncology (DGHO) and the Society of Thrombosis and Hemostasis Research (GTH)

Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPN) comprise a heterogeneous group of chronic hematologic malignancies. The quality of life, morbidity, and mortality of patients with MPN are primarily affected by disease-related symptoms, thromboembolic and hemorrhagic complications, and progression to myelofibrosis and acute leukemia. Major bleeding represents a common and important complication in MPN, and the incidence of such bleeding events will become even more relevant in the future due to the increasing disease prevalence and survival of MPN patients. This review discusses the causes, differential diagnoses, prevention, and management of bleeding episodes in patients with MPN, aiming at defining updated standards of care in these often challenging situations.

How I treat myelofibrosis

Myelofibrosis (MF) is a BCR-ABL1-negative myeloproliferative neoplasm characterized by clonal myeloproliferation, dysregulated kinase signaling, and release of abnormal cytokines. In recent years, important progress has been made in the knowledge of the molecular biology and the prognostic assessment of MF. Conventional treatment has limited impact on the patients' survival; it includes a wait-and-see approach for asymptomatic patients, erythropoiesis-stimulating agents, androgens, or immunomodulatory agents for anemia, cytoreductive drugs such as hydroxyurea for the splenomegaly and constitutional symptoms, and splenectomy or radiotherapy in selected patients. The discovery of the Janus kinase (JAK)2 mutation triggered the development of molecular targeted therapy of MF. The JAK inhibitors are effective in both JAK2-positive and JAK2-negative MF; one of them, ruxolitinib, is the current best available therapy for MF splenomegaly and constitutional symptoms. However, although ruxolitinib has changed the therapeutic scenario of MF, there is no clear indication of a disease-modifying effect. Allogeneic stem cell transplantation remains the only curative therapy of MF, but due to its associated morbidity and mortality, it is usually restricted to eligible high- and intermediate-2-risk MF patients. To improve current therapeutic results, the combination of JAK inhibitors with other agents is currently being tested, and newer drugs are being investigated.

Splenectomy in patients with myeloproliferative neoplasms: efficacy, complications and impact on survival and transformation

Splenectomy may be an effective therapeutic option for treating massive splenomegaly in patients with myeloproliferative neoplasms (MPNs). There are still limited data on its short- and long-term benefits and risks. Efficacy and short-term complications were analyzed in 94 patients with different MPNs who underwent splenectomy at M. D. Anderson Cancer Center. The long-term impact of splenectomy on overall survival (OS) and transformation free survival (TFS) was evaluated in 461 patients with myelofibrosis (MF) seen at M. D. Anderson, including 50 who underwent splenectomy during disease evolution. Splenectomy improved anemia and thrombocytopenia in 47% and 66% of patients, respectively. The most common complications were leukocytosis (76%), thrombocytosis (43%) and venous thromboembolism (16%). Post-operative mortality was 5%. Among patients with MF, splenectomy during disease evolution was associated with decreased OS (hazard ratio [HR] = 2.17, p < 0.0001) and TFS (HR = 2.17, p < 0.0001). This effect was independent of the Dynamic International Prognostic Scoring System. Splenectomy is a possible therapeutic option for patients with MF and other MPNs, and its greatest benefits are related to improvement in spleen pain and discomfort, anemia and thrombocytopenia. However, in patients with MF it appears to be associated with increased mortality.

Hepatic manifestations in hematological disorders

Liver involvement is often observed in several hematological disorders, resulting in abnormal liver function tests, abnormalities in liver imaging studies, or clinical symptoms presenting with hepatic manifestations. In hemolytic anemia, jaundice and hepatosplenomegaly are often seen mimicking liver diseases. In hematologic malignancies, malignant cells often infiltrate the liver and may demonstrate abnormal liver function test results accompanied by hepatosplenomegaly or formation of multiple nodules in the liver and/or spleen. These cases may further evolve into fulminant hepatic failure.

Myelofibrosis: an update on current pharmacotherapy and future directions

INTRODUCTION

Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by symptoms mainly derived from anemia and splenomegaly and constitutional symptoms and associated with a median survival around 6 years. Allogeneic stem cell transplantation (allo-SCT) remains the only curative therapy of MF but is applicable to a minority of patients. Discovery of the JAK2 mutation has provided the basis for the introduction of a new class of drugs, the JAK inhibitors, in the treatment of MF.

AREAS COVERED

A literature review on the therapy of MF has been performed through a PubMed search, with special attention being paid to the available data on transplantation, the JAK inhibitors, and other new drugs.

EXPERT OPINION

Conventional therapy of MF is usually adjusted to the predominant clinical symptoms in each patient, and its impact on survival is limited. Reduced-intensity conditioning regimens have increased the number of patients eligible for allo-SCT, but this procedure is still associated with substantial morbidity and mortality. The JAK inhibitors, such as ruxolitinib, can achieve profound symptomatic relief of the splenomegaly and the constitutional symptoms. However, they often accentuate the anemia and do not reduce the JAK2 allele burden, therefore lacking the potential to modify the natural history of MF.

How I treat splenomegaly in myelofibrosis

Symptomatic splenomegaly, a frequent manifestation of myelofibrosis (MF), represents a therapeutic challenge. It is frequently accompanied by constitutional symptoms and by anemia or other cytopenias, which make treatment difficult, as the latter are often worsened by most current therapies. Cytoreductive treatment, usually hydroxyurea, is the first-line therapy, being effective in around 40% of the patients, although the effect is often short lived. The immunomodulatory drugs, such as thalidomide or lenalidomide, rarely show a substantial activity in reducing the splenomegaly. Splenectomy can be considered in patients refractory to drug treatment, but the procedure involves substantial morbidity as well as a certain mortality risk and, therefore, patient selection is important. For patients not eligible for splenectomy, transient relief of the symptoms can be obtained with local radiotherapy that, in turn, can induce severe and long-lasting cytopenias. Allogeneic hemopoietic stem cell transplantation is the only treatment with the potential for curing MF but, due to its associated morbidity and mortality, is usually restricted to a minority of patients with poor risk features. A new class of drugs, the JAK2 inhibitors, although also palliative, are promising in the splenomegaly of MF and will probably change the therapeutic algorithm of this disease.

Portal hypertension secondary to myelofibrosis with myeloid metaplasia: A study of 13 cases

AIM: To describe the clinical presentation and complications of portal hypertension (PH) secondary to myelofibrosis with myeloid metaplasia (MMM).

METHODS: Medical records for 123 patients with MMM were reviewed.

RESULTS: Thirteen patients with PH secondary to MMM were identified. Median ages at time of MMM and PH diagnosis were 61 and 66 years, respectively. The interval from MMM diagnosis to presentation with one of the PH features ranged from 1 to 11 years. Variceal bleeding and ascites were the most common presentations. Of the eight patients who presented with variceal bleeding, six patients underwent endoscopic variceal ligation (EVL) with no variceal recurrence or hematological worsening during a 12-mo follow up period.

CONCLUSION: Patients with MMM might develop PH. Exact mechanisms leading to PH in MMM are still controversial. As in other etiologies, variceal bleeding and ascites are the most common presentations. Anemia may correlate with, and/or predict, the severity of the PH presentation in these patients. EVL can successfully control variceal bleeding in MMM. Further clinical studies are required.

Extramedullary erythropoiesis in the adult liver requires BMP-4/Smad5-dependent signaling

OBJECTIVE

In mice, homeostatic erythropoiesis occurs primarily in the bone marrow. However, in response to acute anemia, bone morphogenetic proteins 4 (BMP-4)-dependent stress erythropoiesis occurs in the adult spleen. BMP-4 can also regulate stress erythropoiesis in the fetal liver. In humans, erythropoiesis occurs in the bone marrow. However, in certain pathological conditions, extramedullary erythropoiesis is observed, where it can occur in several organs, including the liver. Given these observations, we propose to investigate whether the BMP-4-dependent stress erythropoiesis pathway can regulate extramedullary erythropoiesis in the livers of splenectomized mice.

MATERIALS AND METHODS

Using splenectomized wild-type and flexed-tail (f) mice, which have a defect in BMP-4 signaling, we compared their recovery from phenylhydrazine-induced hemolytic anemia and characterized the expansion of stress burst-forming unit-erythroid in the livers of these mice during the recovery period.

RESULTS

Our analysis indicates that in the absence of a spleen, stress erythropoiesis occurs in the murine liver. During the recovery, stress burst-forming unit-erythroid are expanded in the livers of splenectomized mice in response to BMP-4 expressed in the liver. f/f mice, which exhibit a defect in splenic stress erythropoiesis do not compensate for this defect by upregulating liver stress erythropoiesis. Furthermore, splenectomized f/f mice exhibit a defect in liver stress erythropoiesis, which demonstrates a role for the BMP-4-dependent stress erythropoiesis pathway in extramedullary erythropoiesis in the adult liver.

CONCLUSIONS

Our data indicate that the BMP-4-dependent stress erythropoiesis pathway regulates extramedullary stress erythropoiesis, which occurs primarily in the murine spleen or in the case of splenectomized mice, in the adult liver.

Myelofibrosis with myeloid metaplasia: disease overview and non-transplant treatment options

Myelofibrosis with myeloid metaplasia (MMM) is currently classified as a classic (i.e. not yet molecularly defined) myeloproliferative disorder (MPD), along with essential thrombocythemia (ET) and polycythemia vera (PV). All three MPDs represent stem-cell-derived clonal myeloproliferation that, in the case of MMM, is accompanied by an intense bone marrow stromal reaction that includes collagen fibrosis, osteosclerosis, and angiogenesis. To date, both the molecular basis of the primary clonal process and the pathogenetic mechanisms that underlie the secondary histological changes remain elusive. Clinically, MMM is characterized by anemia, multi-organ extramedullary hematopoiesis that often involves the spleen and liver, constitutional symptoms, and premature death from either leukemic transformation or other disease complications. Current diagnosis is based on characteristic but not diagnostic bone marrow histological features. Modern therapy remains palliative but allogeneic stem cell transplantation might be curative to a selected group of patients. This chapter reviews both the old and the new therapy with regard to non-transplant treatment options for MMM.

Extramedullary hematopoiesis mimicking acute appendicitis: a rare complication of idiopathic myelofibrosis

Extramedullary hematopoiesis (EMH) is rarely found in the gastrointestinal tract. To our knowledge, EMH involving the appendix was not described. We report a case with a previous history of idiopathic myelofibrosis, which presented with clinical findings of acute appendicitis that necessitate appendectomy after the relief of his anemia. Microscopic examination and immunohistochemistry revealed foci of EMH throughout the mucosa and the submucosa. In the latter, small clusters of hematopoietic cells were also detected in a few dilated vascular structures. The histopathological features of acute appendicitis were not observed. Our case supports that EMH might develop in organs that are not involved in hematopoiesis. Although in gastrointestinal system, obstruction and bleeding are the most common symptomatic manifestations, this case emphasizes that EMH might also present clinically as acute appendicitis. The absence of histopathological features of acute appendicitis raises the possibility that local production of some mediators from hematopoietic precursor cells might contribute to this clinical presentation.

Late follow-up of patients submitted to subtotal splenectomy

BACKGROUND

Over the past 21years, we have performed more than 200 subtotal splenectomies, in which the upper splenic pole vascularized only by the gastrosplenic pole vascularized only by the gastrosplenic vessels is preserved, to treat different pathologic conditions. A meticulous follow-up of the postoperative results of this procedure is of fundamental importance.

METHODS

All patients undergoing subtotal splenectomy were invited to be reviewed. A total of 86 patients who had undergone surgery 1-20years ago were gathered; the surgical procedure was performed for one of the following conditions: portal hypertension due to schistosomiasis (n=43), trauma (n=31), Gaucher's disease (n=4), myeloid hepatosplenomegaly due to myelofibrosis (n=3), splenomegalic retarded growth and sexual development (n=2), severe pain due to splenic ischemia (n=2) and pancreatic cystadenoma (n=1). Patients underwent a hematological examination, an immunological assessment, abdominal ultrasonography, computed tomography, scintigraphy and endoscopy.

RESULTS

Increased white blood cell count and platelets were the only hematological abnormalities. No immunological deficit was found. Esophageal varices were still present in patients who underwent surgery because of portal hypertension although without rebleeding. The ultrasound, tomography and scintigraphy examinations confirmed the presence of functional splenic remnants without significant size alteration.

CONCLUSIONS

Subtotal splenectomy seems to be a safe procedure that can be useful in treating conditions involving the spleen. The functions of the splenic remnants are preserved during long periods of time.

Idiopathic myelofibrosis: pathogenesis to treatment

Idiopathic myelofibrosis (IMF) is the least common of the chronic myeloproliferative disorders and carries the worst prognosis with a median survival of 4 years. It is a clonal haematopoietic stem-cell disorder and, although the pathogenesis remains unclear, approximately 50% of cases are known to possess an activating JAK2 V617F mutation. In contrast, the characteristic stromal proliferation is a reactive, or secondary, event that results from the aberrant release of a variety of growth factors from megakaryocytes and monocytes. Treatment for most cases is supportive, although androgens, recombinant erythropoietin, steroids and thalidomide are effective modalities for the amelioration of anaemia. Myelosuppression, splenectomy and irradiation are valuable therapeutic modalities for specific clinical situations. Prognostic scores are available to aid the identification of cases for whom bone marrow transplantation should be considered. Recently, the use of reduced intensity conditioning has resulted in prolonged survival and lower transplant-related mortality. This review summarises the recent advances in the disease's pathogenesis and discusses the role of the various therapeutic options.

Late postoperative follow-up of patients undergoing subtotal splenectomy

PURPOSE

Over the past 21 years, we have performed more than 200 subtotal splenectomies, in which the upper splenic pole vascularized only by the gastrosplenic pole vascularized only by the gastrosplenic vessels is preserved, to treat different pathologic conditions. A meticulous follow-up of the postoperative results of this procedure is of fundamental importance.

METHODS

All patients undergoing subtotal splenectomy were invited to be reviewed. A total of 86 patients who had undergone surgery 1 to 20 years ago were gathered; the surgical procedure was performed for one of the following conditions: portal hypertension due to schistosomiasis (n = 43), trauma (n = 31), Gaucher's disease (n = 4), myeloid hepatosplenomegaly due to myelofibrosis (n = 3), splenomegalic retarded growth and sexual development (n = 2), severe pain due to splenic ischemia (n = 2) and pancreatic cystadenoma (n = 1). Patients underwent a hematologic exam, an immunologic assessment, abdominal ultrasonography, computed tomography, scintigraphy and endoscopy.

RESULTS

Increased white blood cell count and platelets were the only hematological abnormalities. No immunologic deficit was found. Esophageal varices were still present in patients who underwent surgery because of portal hypertension although without rebleeding. The ultrasound, tomography and scintigraphy exams confirmed the presence of functional splenic remnants without significant size alteration.

CONCLUSIONS

Subtotal splenectomy seems to be a safe procedure that can be useful in treating conditions involving the spleen. The functions of the splenic remnants are preserved during long periods of time.

Portal hypertension secondary to myelofibrosis: a study of three cases

BACKGROUND

In patients with idiopathic myelofibrosis (IM), portal hypertension (PHT) without thrombosis of the hepatic or splenoportal veins is infrequent.

OBJECTIVE

To ascertain the mechanisms responsible for the development of PHT in IM and their therapeutic implications.

PATIENTS AND METHODS

Color Doppler ultrasound with portal flow quantification, hepatic hemodynamic studies, and histological examinations of the liver biopsies were performed in three IM patients with PHT in whom hepatic and splenoportal thrombosis were ruled out.

RESULTS

Two patients showed sinusoidal PHT (increased hepatic venous pressure gradient), normal portal flow, and massive myeloid metaplasia of the liver. Transjugular intrahepatic portosystemic shunt (TIPS) was indicated for variceal bleeding and ascites unresponsive to medical therapy, and resulted in an adequate control of these PHT complications. At the time of TIPS placement, direct portal pressure measurement showed a marked presinusoidal component in the PHT. A third patient died as a consequence of the IM before treatment of PHT could be instituted. This patient showed an extremely increased portal flow and lesser hepatic infiltration.

CONCLUSIONS

IM patients with PHT might have a marked presinusoidal component contributing to PHT that is underestimated by hepatic vein catheterization. Treatment of the complications of PHT might not differ from that of patients with cirrhosis.

Modern management of myelofibrosis

The conventional treatment of myelofibrosis involves a wait-and-see approach for asymptomatic patients, oral chemotherapy for the hyperproliferative forms of the disease, androgens or erythropoietin for the anaemia, and splenectomy in selected patients. Low-dose thalidomide plus prednisone is a well-tolerated therapy for the anaemia and the thrombocytopenia of myelofibrosis, whereas imatinib has shown little efficacy. Allogeneic stem cell transplantation (allo-SCT) is the only curative therapy for myelofibrosis. Its standard modality has an associated mortality of about 30% and can be applied to younger patients with high-risk disease or resistant to conventional treatment. Reduced-intensity conditioning allo-SCT involves a low mortality and is a promising therapy for patients aged 45-70 years old with the above characteristics. Autologous SCT is a palliative therapy for patients resistant to conventional treatment who lack a suitable donor. The next candidates for the treatment of myelofibrosis are the thalidomide derivatives, the proteasome inhibitors, and vascular endothelial growth factor neutralizing antibodies.

Long-term analysis of the palliative benefit of 2-chlorodeoxyadenosine for myelofibrosis with myeloid metaplasia

OBJECTIVE

Therapeutic splenectomy in myelofibrosis with myeloid metaplasia (MMM) may result in extreme thrombocytosis and leukocytosis and accelerated hepatomegaly. We previously described initial palliative benefit from 2-chlorodeoxyadenosine (2-CdA) in such instances. The purpose of this study is to provide long-term follow-up on the durability of response in the initial cohort and in additional subsequent cases.

METHODS

We retrospectively identified patients with histologically confirmed MMM who had palliative therapy with 2-CdA. Clinical characteristics and information on subsequent clinical course were abstracted at the time of diagnosis of MMM and at initiation of 2-CdA therapy until death.

RESULTS

To date, we have used 2-CdA as palliative therapy in 14 patients with MMM. After a median of four cycles of therapy, responses for hepatomegaly occurred in 56% of patients, thrombocytosis 50%, leukocytosis 55%, and anemia 40%. Cytopenias were frequent but usually transient and without clinical consequence. Responses occurred usually by the second cycle; median duration of response was 6 months (range, 2-19) after completion of 2-CdA therapy.

CONCLUSION

This study confirmed relevant and frequently durable palliation of symptoms in about half the patients. 2-CdA is a reasonable palliative option in postsplenectomy patients with MMM who have problematic myeloproliferation.

Roles of spleen and liver in development of the murine hematopoietic system

OBJECTIVE

Hematopoietic stem cells (HSCs) and colony-forming progenitor cells (CFCs) are believed to migrate from liver to bone marrow (BM) around the time of birth, where they remain throughout the animal's life. Although in mice the spleen is also a hematopoietic organ, neither the origin nor the contribution of spleen HSCs to hematopoietic homeostasis has been assessed relative to that of BM HSCs. To investigate these issues we quantitated CFC and HSC activity in the spleen, BM, peripheral blood, and liver of the mouse during ontogeny.

METHODS

CFCs were assessed by clonogenic colony formation, and HSCs by long-term reconstituting ability.

RESULTS

CFCs gradually increased in the BM and decreased in the liver with age. Increased prevalence of CFCs in fetal and pup blood occurred at day (d) 12 postcoitus (pc) and during the period of d16 pc to 4d postbirth, corresponding to the times when hematopoietic cells migrate from the yolk sac and/or aorta-gonad-mesonephros (AGM) to the fetal liver and from the neonatal liver to the BM, respectively. In the spleen, CFCs displayed two peaks of activity at 2d and 14d-15d postbirth. Spleen HSCs also fluctuated during this time period. Neonatal splenectomy did not alter CFC or HSC frequencies in the BM, but CFCs increased in the livers of splenectomized mice.

CONCLUSIONS

These data demonstrate that the liver may act as a site of extramedullary hematopoiesis in the neonate, especially in the absence of the spleen, and imply that the spleen, BM, and liver cooperatively contribute to hematopoietic homeostasis.

The therapy of myelofibrosis: targeting pathogenesis

Myelofibrosis with myeloid metaplasia (MMM) encompasses the diagnoses of agnogenic myeloid metaplasia (idiopathic myelofibrosis), as well as the advanced phases of polycythemia vera and essential thrombocythemia (post polycythemic and post thrombocythemia myeloid metaplasia, respectively). MMM is a clonal, hematopoietic stem cell disorder in which neither the pathogenesis, nor a broadly applicable effective therapy have been described. Clinically, these patients experience progressive marrow replacement by fibrotic tissue, ineffective hematopoiesis, problematic cytopenia's, significant hepato-splenomegaly, extramedullary hematopoiesis, profound constitutional symptoms, and a risk of blastic transformation. Historically, therapies have been targeted at palliating symptoms (i.e. splenectomy, transfusions, hydroxyurea, erythropoietin, androgens, localized radiotherapy). Stem cell transplantation appears promising, but is often toxic and not broadly applicable due to co-morbidities and age of MMM patients. Non-myeloablative approaches to conditioning may broaden the applicability of stem cell transplantation in MMM, yet results to date are preliminary. Although a definitive molecular abnormality responsible for the pathogenesis of MMM has not been described, much has been learned about the aberrant expression of pro-fibrotic cytokines and the presence of increased angiogenesis in MMM. These pathogenetic insights have led to a series of pilot clinical trials with therapeutic agents targeting aberrantly expressed cytokines (and possibly angiogenesis) including Thalidomide (alone or in combination), Etanercept, and STI-571. Amongst these later agents Thalidomide has demonstrated the most promise (palliating disease associated cytopenia's), whereas the TNF-alpha inhibitor Etanercept has aided with MMM associated constitutional symptoms. Although these later trials have been helpful in a subset of patients, no agent to date has led to solid complete responses in MMM across the spectrum of disease manifestations. Further insights into the pathogenetic mechanisms responsible for myeloproliferation (aberrant cell signaling pathways, apoptotic resistance, other) are necessary to guide selection and testing of the expanding number of novel anti-neoplastic agents in chronic myeloid disorders and MMM.

Orbital apex syndrome: a rare presentation of extramedullary hematopoiesis: case report and review of literature

We describe a case of compressive neuropathy in the orbital apex due to extramedullary hematopoiesis (EMH). A 64-year-old man with Polycythemia Rubra Vera developed unilateral visual loss, proptosis, complete ophthalmoplegia, and facial paresis. Bone marrow biopsy showed myelofibrosis. Magnetic resonance imaging demonstrated enhancement at the orbital apex and subtle optic canal narrowing. Decompression of the optic nerve with biopsy of surrounding bone showed EMH. The patient received a course of radiation without benefit. We suggest including the diagnosis of EMH of the orbital apex bones in the differential diagnosis of patients with myeloproliferative disorders who develop an orbital apex syndrome.

Palliative splenectomy in myelofibrosis with myeloid metaplasia

Myelofibrosis with myeloid metaplasia (MMM) is a chronic myeloproliferative disorder in which the accumulation and growth of circulating myeloid progenitors in the spleen lead to pathologic enlargement of the organ with resulting mechanical discomfort, hypercatabolic symptoms, anemia, thrombocytopenia, and portal hypertension. Medical therapy and splenic irradiation may be of benefit in certain patients, yet many may still require splenectomy to palliate their symptoms. Although there is no clear survival advantage to splenectomy in MMM, the procedure can result in substantial palliation of symptoms. However, the surgical procedure is associated with an approximately 9% mortality rate, and the postsplenectomy occurrence of extreme thrombocytosis, hepatomegaly, and leukemic transformation is of major concern. The management of splenomegaly and the role of splenectomy in MMM are discussed in this review.

Risks and benefits of splenectomy in myelofibrosis with myeloid metaplasia: a retrospective analysis of 26 cases

BACKGROUND AND OBJECTIVES

To evaluate the outcomes of splenectomy in myelofibrosis and myeloid metaplasia (MMM).

METHODS

We retrospectively reviewed our records of 26 patients with MMM who underwent an open splenectomy at Boston University Medical Center between 1979 and 1995. Fourteen patients had agnogenic myeloid metaplasia (AMM) and 12 had myelofibrosis with antecedent myeloproliferative disorders (MF). The main indications for splenectomy were progressive transfusion-dependent anemia, painful splenomegaly, and hypercatabolic symptoms associated with cytopenia.

RESULTS

Median time to splenectomy after the diagnosis of MMM was 29 months ranging from 1 to 96 months. Three patients (11%) died within 1 month after the surgery because of sepsis. The most common peri- and postoperative complications were pneumonia and other bacterial infections (42%), cardiac events (19%), acute bleeding (15%), ileus (15%), and venous thrombosis (12%). Of the eight surviving patients who underwent splenectomy for transfusion dependent anemia, six (75%) had improvement in their hematocrit levels with abolishment of blood transfusions. A durable symptomatic palliation was achieved in all patients. Liver enlargement was noted in seven patients at 1-year evaluation. None of these patients developed hepatic failure. Leukemic transformation occurred in 8 of 18 patients (44%) postsplenectomy. The median overall survival for the entire group was 58.5 and 28 months from the diagnosis of MMM and the time of splenectomy, respectively. There was no difference in survival rates between patients with AMM and MF.

CONCLUSIONS

Splenectomy is an effective palliative procedure with an acceptable morbidity in selected patients with MMM. Progressive transfusion-dependent anemia should also be considered an indication for splenectomy in the absence of leukemic evolution.

Prognostic factors and current practice in treatment of myelofibrosis with myeloid metaplasia: an update anno 2000

Median survival of patients with myelofibrosis with myeloid metaplasia (MMM) ranges from 3.5 to 5 years, but there is a wide variability. The degree of anemia (Hb < 10 g/dL) is the most important prognostic factor, followed by constitutional symptoms and abnormal karyotype. In recent years, different prognostic scoring systems for MMM have been proposed. In some of them three prognostic groups (low, intermediate, and high risk) are recognized, while others recognize a high and a low-risk group only. Median survival of the low-risk group ranges from seven to nine years, while the minority of high-risk patients survive for a median of less than two years. Younger patients with MMM survive longer (median survival above ten years). Among the latter patients, based on Hb value, constitutional symptoms, and blood blast-cell percentage, two prognostic groups can also be identified, with median survival of less than three years and almost 15 years, respectively. Conventional treatment of MMM is mostly palliative and based on cytolytic treatment (usually hydroxyurea), androgen therapy and splenectomy in selected patients. Allogeneic hemopoietic transplant is a therapeutic possibility with the potential for cure in younger patients with bad prognostic features. The role in MMM of newer treatment strategies such as autologous transplantation or the administration of anti-angiogenic drugs such as thalidomide is currently being evaluated.

Radiation therapy for symptomatic hepatomegaly in myelofibrosis with myeloid metaplasia

OBJECTIVE

To describe the experience with liver irradiation in advanced cases of myelofibrosis with myeloid metaplasia (MMM).

METHODS

Over a 20-yr period, 14 patients with MMM were treated with a total of 25 courses of liver, abdominal, or abdominal and pelvic irradiation for symptomatic hepatomegaly with (5 patients) or without (9 patients) ascites. All 14 patients had advanced disease and 11 (79%) had previous splenectomy. The median radiation therapy (RT) dose per course was 150 cGy (range 50-1000) administered at a median of six fractions. Four patients received two to six courses.

RESULTS

Twelve of the 14 patients (86%) had a transient (median 3 months) subjective response from RT. However, in only 35% of these was there a transient (median 3 months) decrease in palpable liver size. Four of the five patients with ascites experienced a short-term response from RT. Eight of the 13 patients suitable for evaluation (62%) had treatment-associated cytopenia, often in the form of anemia and/or thrombocytopenia. At last follow-up, 10 patients (71%) had died after a median of 7 months (range 0.1-23) and 4 were alive at 3, 20, 33, and 57 months after RT.

CONCLUSIONS

Low-dose abdominal RT for symptomatic hepatomegaly or ascites associated with advanced-stage MMM is myelosuppressive and provides only temporary and mainly subjective and short-lived relief.

Splenectomy in chronic myeloid leukemia and myelofibrosis with myeloid metaplasia

Myelofibrosis with myeloid metaplasia (MMM) is a collective term that describes the related disorders AMM, PPMM, and PTMM. The chronic myeloid disorders include chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, and agnogenic myeloid metaplasia (myelofibrosis). These disorders display varying propensities for pathologic enlargement of the spleen which can lead to mechanical discomfort, hypercatabolic symptoms, anemia, thrombocytopenia, and portal hypertension. Splenectomy has been found to be of little benefit in the early stages of chronic myeloid leukemia. Similarly, the benefit of splenectomy in advanced cases is limited to symptomatic palliation and treatment of delayed engraftment after allogeneic bone marrow transplantation. Although polycythemia vera and essential thrombocythemia are also characterized by splenomegaly, splenectomy is not considered a therapeutic option in the absence of transformation of the disease into myelofibrosis with myeloid metaplasia. Splenectomy has been studied most in myelofibrosis with myeloid metaplasia. Although there is no clear survival advantage to splenectomy in this disorder, the surgical procedure can result in substantial palliation of mechanical discomfort, hypercatabolic symptoms, portal hypertension, and anemia. However, the procedure is associated with an approximately 9% mortality rate, and the postsplenectomy occurrence of extreme thrombocytosis, hepatomegaly, and leukemic transformation is of major concern.

Splenectomy in myelofibrosis with myeloid metaplasia: a single-institution experience with 223 patients

In a 20-year period, 223 patients (median age, 64.8 years) with myelofibrosis with myeloid metaplasia (MMM) had therapeutic splenectomy at our institution. Primary indications for surgery were transfusion-dependent anemia (45.3%), symptomatic splenomegaly (39.0%), portal hypertension (10.8%), and severe thrombocytopenia (4.9%). Operative mortality and morbidity rates were 9% and 31%, respectively. The 203 survivors of surgery had a median postsplenectomy survival time (PSS) of 27 months (range, 0-155). Among preoperative variables, thrombocytopenia (platelet count less than 100 × 109/L) and nonhypercellular bone marrow were identified as independent risk factors for decreased PSS. Durable remissions in constitutional symptoms, transfusion-dependent anemia, portal hypertension, and severe thrombocytopenia were achieved in 67%, 23%, 50%, and 0% of the patients, respectively. Histologic or cytogenetic features of bone marrow obtained before splenectomy did not predict a response in cytopenias. After splenectomy, substantial enlargement of the liver and marked thrombocytosis occurred in 16.1% and 22.0% of the patients, respectively. The thrombocytosis was associated with an increased risk of perioperative thrombosis and decreased PSS. The rate of blast transformation (BT) was 16.3%, and the risk of BT was higher in the presence of increased spleen mass and preoperative thrombocytopenia. However, the PSS of patients with BT was not significantly different from that of patients without BT. We conclude that presplenectomy thrombocytopenia in MMM may be a surrogate for advanced disease and is associated with an increased risk of BT and inferior PSS. However, the development of BT after splenectomy may not affect overall survival and does not undermine the palliative role of the procedure for the other indications.

Splenectomy in myelofibrosis with myeloid metaplasia: a single-institution experience with 223 patients

In a 20-year period, 223 patients (median age, 64.8 years) with myelofibrosis with myeloid metaplasia (MMM) had therapeutic splenectomy at our institution. Primary indications for surgery were transfusion-dependent anemia (45.3%), symptomatic splenomegaly (39.0%), portal hypertension (10.8%), and severe thrombocytopenia (4.9%). Operative mortality and morbidity rates were 9% and 31%, respectively. The 203 survivors of surgery had a median postsplenectomy survival time (PSS) of 27 months (range, 0-155). Among preoperative variables, thrombocytopenia (platelet count less than 100 × 109/L) and nonhypercellular bone marrow were identified as independent risk factors for decreased PSS. Durable remissions in constitutional symptoms, transfusion-dependent anemia, portal hypertension, and severe thrombocytopenia were achieved in 67%, 23%, 50%, and 0% of the patients, respectively. Histologic or cytogenetic features of bone marrow obtained before splenectomy did not predict a response in cytopenias. After splenectomy, substantial enlargement of the liver and marked thrombocytosis occurred in 16.1% and 22.0% of the patients, respectively. The thrombocytosis was associated with an increased risk of perioperative thrombosis and decreased PSS. The rate of blast transformation (BT) was 16.3%, and the risk of BT was higher in the presence of increased spleen mass and preoperative thrombocytopenia. However, the PSS of patients with BT was not significantly different from that of patients without BT. We conclude that presplenectomy thrombocytopenia in MMM may be a surrogate for advanced disease and is associated with an increased risk of BT and inferior PSS. However, the development of BT after splenectomy may not affect overall survival and does not undermine the palliative role of the procedure for the other indications.

Pathogenesis and management of idiopathic myelofibrosis

Idiopathic myelofibrosis is the least common and carries the worst prognosis of the chronic myeloproliferative disorders. The primary disease process is a clonal haematopoietic stem cell disorder which results in a chronic myeloproliferation and an atypical megakaryocyte hyperplasia. In contrast, the characteristic stromal proliferation is a reactive phenomenon, resulting from the inappropriate release of megakaryocyte/platelet-derived growth factors, including PDGF, TGF-beta bFGF and calmodulin. The median survival is approximately 4 years, although individual survival varies greatly. A variety of prognostic schema have been developed which enable the identification of high-risk patients, for whom bone marrow transplantation should be considered. Management for the majority of patients, however, is directed towards the alleviation of symptoms and improvement in quality of life. This review summarizes the recent advances in our understanding of the disease's pathogenesis and discusses the limited therapeutic options available to clinicians.

Idiopathic myelofibrosis: pathogenesis, natural history and management

Idiopathic myelofibrosis is a chronic myeloproliferative disorder characterized by bone marrow fibrosis, extramedullary haematopoiesis and a leucoerythroblastic blood picture. The marrow fibrosis results from an increased deposition of various interstitial and basement membrane glycoproteins, including collagen types I, III, IV, V and VI, fibronectin, vitronectin, laminin and tenascin. In addition, a marked neovascularization is present, even in the early proliferative phase of the disease. In contrast to the clonal haematopoiesis, the increased bone marrow stromal tissue is thought to be a reactive phenomenon, resulting from the inappropriate release of megakaryocyte/platelet-derived growth factors, including PDGF, TGF-beta, EGF, bFGF and calmodulin. Recent cytogenetic studies have highlighted three defects, namely del(13q), del(20q) and partial trisomy 1q, that account for nearly 70% of all abnormalities at diagnosis, and suggests that in many patients gene loss and/or inactivation may be an important pathogenetic mechanism. The median survival is approximately 4 years, although individual survival varies greatly. Prognostic schema enable the identification of patients with a limited life expectancy, for whom bone marrow transplantation should be considered. However, for the majority of patients therapy is supportive and consists of blood transfusions, androgens to sustain erythropoiesis, cytoreductive agents to prevent thrombocythaemia and, in carefully selected cases, splenectomy. The role for a number of experimental therapies, such as vitamin D3 analogues, alpha and gamma interferons and erythropoietin has yet to be defined.

Endoscopic injection sclerotherapy for esophageal variceal hemorrhage in a patient with idiopathic myelofibrosis

A 74-year-old female with idiopathic myelofibrosis (IMF) was admitted to our hospital because of massive hematemesis and melena. Immediate upper gastrointestinal endoscopy revealed an intermittent spurting hemorrhage from extensive esophageal varices. Endoscopic injection sclerotherapy (EIS) was carried out and the bleeding ceased. After five courses of EIS, all the esophageal varices were eradicated. About 15 months later, the patient died, due to a cerebral hemorrhage, without further variceal bleeding. A postmortem examination was carried out and the portal hypertension was considered to be due not only to extramedullary hematopoiesis in the sinusoids, but also to increased splenic blood flow. We are confident that EIS is an effective therapeutic procedure for patients with IMF showing esophageal variceal hemorrhage. EIS should be the preferred choice of treatment for esophageal varices in patients with IMF, since it is less invasive than splenectomy.

Idiopathic myelofibrosis--an update with particular reference to clinical aspects and prognosis

Idiopathic myelofibrosis (IMF) is characterized by excessive accumulation of connective tissue in the bone marrow as part of a clinical syndrome which in its classical form is featured by leukoerythroblastic anemia and huge splenomegaly at the time of diagnosis. An acute variant of the disease exists being featured by pancytopenia, nor or minimal splenomegaly and a rapidly fatal clinical course. This review describes the relationship of IMF to other chronic myeloproliferative disorders and highlights current concepts of the pathogenesis of bone marrow fibrosis, implicating the intramedullary release of various growth factors, including platelet-derived growth factor beta. In a subgroup of patients bone marrow fibrosis may develop consequent to autoimmune bone marrow damage. The clinical and laboratory findings in some of the larger series of patients are presented and the reasons for the highly variable clinical presentation and prognosis are critically discussed. It is proposed that studies on prognosis in IMF are based upon simple prognostic staging systems, which should include the Hb-concentration, platelet count, spleen size and the presence/absence of osteomyelosclerosis on X-ray. Using these parameters the patients are easily categorized into three prognostic groups with highly different survival times.