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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 x 10(9/)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.

To provide basic information about occurrence and outcome of essential thrombocythemia (ET) and agnogenic myeloid metaplasia (AMM), we used the Rochester Epidemiology Project medical record linkage system for residents of Olmsted County, Minnesota. We identified all residents who were diagnosed with ET or AMM from 1976 to 1995. Community inpatient and outpatient medical records were reviewed to verify the diagnosis of ET or AMM, and patients were followed passively through their medical records to determine the outcome after diagnosis. We identified 39 cases of ET and 21 of AMM, with age- and sex-adjusted incidence rates of 2.53 and 1.46 cases/100,000 population annually, respectively. The respective median ages at diagnosis were 72 and 67 years. The female-to-male ratios were 1.8 and 1.6 for ET and AMM, respectively, and when adjusted for age, there was no difference in risk. The median follow-up period was 62.9 months for ET and 33.2 months for AMM. Five- and 10-year survivals were 74.4% and 61.3%, respectively, for ET and were significantly lower than expected for age-matched controls (P = 0.012). Prognosis was worse for AMM, with a median progression time of 7 months and a 3-year survival of 52.4%. This was significantly worse than for age-matched controls (P < 0.001). This study provides population-based incidence and comparative survival figures in ET and AMM.

Twenty-three patients who had myelofibrosis with myeloid metaplasia (MMM) were treated at our institution with 50 courses of splenic irradiation (SI) for symptomatic splenomegaly. The median dose of radiation per course was 277.5 cGy, administered in a median of 7.5 fractions. 8/23 patients received multiple courses of SI. Of 49 evaluable courses of SI, 46 (93.9%) resulted in an objective decrease in spleen size. The median duration of response was 6 months (range 1-41). Reduction in spleen size was associated with symptomatic relief in all patients. Overall median survival after SI was 22 months. Significant cytopenia occurred in 10 (43.5%) patients, or 16 (32%) of the 50 courses of SI. Prolonged, life-threatening pancytopenia after a single course of SI occurred in six patients (26%), resulting in fatal sepsis or haemorrhage in three (13%). Nine patients underwent subsequent splenectomy: the perioperative mortality rate was 11%. One third of patients experienced postoperative intra-abdominal haemorrhage necessitating surgical re-exploration. SI can provide symptomatic relief and a reduction in spleen size in most MMM patients. The increased risk of postoperative bleeding in patients requiring subsequent splenectomy dictates against considering SI as an alternative to splenectomy for patients who are otherwise good surgical candidates.

2-Chlorodeoxyadenosine (2-CdA) is a purine nucleoside analogue with therapeutic activity in low-grade lymphoproliferative disorders. In addition, 2-CdA has a potent myelosuppressive effect, and it has been shown to be toxic to malignant myeloid cells both in vitro and in vivo. In this pilot study we treated nine patients who had advanced myelofibrosis with myeloid metaplasia (MMM) and progressive hepatomegaly or symptomatic thrombocytosis after therapeutic splenectomy. 2-CdA was administered at 0.05-0.1 mg/kg/d for 7 d for one to five treatment cycles. A reduction in liver size associated with marked improvement in fatigue and control of thrombocytosis and leucocytosis was achieved in seven of the nine patients (78% response rate). In four of the seven responding patients the reduction in liver size was durable (4-28 months) and was associated with a decrease in serum alkaline phosphatase levels. However, no patient had improvement in anaemia, and two of the seven initially responding patients have since died of acute leukaemia or progressive disease. Improvement in bone marrow fibrosis was noted in two of five available post-treatment marrow examinations. Toxicity was mainly myelosuppression, which was severe in two patients. 2-CdA may be considered a palliative therapeutic agent after splenectomy in noncytopenic patients with MMM who have progressive hepatomegaly or extreme thrombocytosis.

Agnogenic myeloid metaplasia (AMM) carries the worst prognosis among the chronic myeloproliferative disorders. Substantial bone marrow fibrosis, extramedullary hematopoiesis, anemia and hepatosplenomegaly are the characteristic features of the disease. AMM is currently incurable and the available treatment agents are mostly palliative and do not prolong life. Two pathogenetic processes are responsible for the impaired hematopoiesis and the clinical manifestations. The primary disease process is a clonal hematopoietic stem cell disorder which results in chronic myeloproliferation and atypical megakaryocytic hyperplasia. The secondary process of bone marrow fibrosis is the result of non-clonal fibroblastic proliferation and hyperactivity induced by growth factors abnormally shed from clonal megakaryocytes. Therefore, experimental treatment strategies may be directed towards either one or both of these disease processes. This report summarizes the current management options and new therapeutic endeavours.

Life-threatening portal hypertension (PHN) in patients with chronic myeloproliferative disorders may result from increased portal flow caused by marked splenomegaly or an increased resistance to portal flow from either a large vein thrombosis or an intrahepatic obstruction usually associated with agnogenic myeloid metaplasia (AMM). The former cause is correctable by splenectomy alone, whereas the latter requires portal-systemic shunt surgery. Few data exist regarding the outcome of portal-systemic shunt surgery in patients with AMM and intrahepatic obstruction. During the past 25 years, 13 patients with chronic myeloproliferative disorders underwent portal-systemic shunt surgery at our institution. The cause of PHN was intrahepatic obstruction in ten patients and hepatic vein thrombosis in three. Ten of the thirteen patients had AMM as initial diagnosis. Only one patient had intraoperative complications, and four patients had either sepsis or thrombosis during the postoperative period. Twelve patients survived the postoperative period and had a median postsurgical survival of 3 years (range, 0.25 to 19 years). The long-term complications of the operation were very few and included hepatic encephalopathy (one patient), portal vein thrombosis (one patient), and shunt occlusion (one patient). The procedure was successful in alleviating complications of PHN in all but one patient. Deterioration of hepatic function and subsequent hepatomegaly were unusual. Portal-systemic shunt surgery seems to be a useful option in patients with AMM and life-threatening PHN from intrahepatic obstruction.

Myeloid metaplasia associated with idiopathic myelofibrosis most commonly involves the reticuloendothelial organs, such as the spleen, liver and retroperitoneal lymph nodes. We report on a patient with myeloid metaplasia (extramedullary hematopoiesis) of the renal pelves, ureters and bladder. The pathogenesis, clinical characteristics, treatment and prognosis of this condition are discussed.

The onset of postpolycythemic myeoloid metaplasia or spent polycythemia has been recognized for many years. As the result of many different series, the development of postpolycythemic myeolid metaplasia might be expected in from 15%-20% of patients with postpolycythemia vera. It appears that an etiologic role for sodium phosphate 32P may exist in this evolutionary pattern. About 70% of patients with PPMM will have symptoms with the onset of the syndrome. The major mechanisms producing symptoms result from (1) anemia, (2) pressure from massive splenomegaly, and (3) bleeding problems. Iron deficiency is a frequent cause of anemia in patients with PPMM. The major mechanism of anemia in these patients, however, relates to ineffective erythropoiesis and shortened red cell survival. Androgen trials for ineffective erythropoiesis seem worthwhile, although data on this point is too limited to draw any firm conclusions. A steroid trial for those patients with major hemolytic episodes is indicated. In those patients in whom adrenal steroid therapy fails to control major hemolysis, a consideration for splenectomy exists. Pressure-related manifestations secondary to massive splenomegaly have been treated with radiation therapy and oral alkylators. Although there is data to document amelioration of painful symptoms with associated shrinking of the spleen, long-term control of this problem has not been forthcoming. Again, patients who are medical failures in control of pressure-related manifestations may be considered for splenectomy. Bleeding problems may arise with PPMM secondary to thrombocytopenia, thrombocythemia, or qualitative platelet dysfunction. Adrenal steroids have met with some success in improving platelet counts in patients with life-threatening thrombocytopenia. Those patients who are medical failures with adrenal steroids in terms of thrombocytopenia might be candidates for splenectomy. Control of thrombocythemia has been observed with oral alkylator therapy and chlorambucil may have a special role in managing this complication. Qualitative platelet defects leading to severe bleeding are best managed with fresh platelet transfusions. Patients with PPMM in contrast to patients with agnogenic myeoloid metaplasia have a more lethal syndrome and shortened survivorship. Causes of death in patients with PPMM include cardiac problems, transition to acute leukemia, hemorrhage, and infection.

Between 1960 and 1977, 50 patients with agnogenic myeloid metaplasia were splenectomized. Twenty-five of 26 patients with painful splenomegaly, 4 of 9 patients with refractory hemolytic anemia, 4 of 10 patients with refractory thrombocytopenia, and 4 of 4 patients with portal hypertension showed significant benefit from the procedure. There were five immediate postoperative deaths. Four of these deaths occurred early in our series of splectomies for myeloid metaplasia before 1970. Only one death has occurred in the last 21 patients operated on. Survival following splenectomy averaged 25.5 mo.

Teardrop-shaped erythrocytes (TD) are frequently observed in the peripheral blood of patients with agnogenic myeloid metaplasia (AMM). These deformed cells may result from the myelofibrosis or the extramedullary hematopoiesis in the spleen. To determine the influence of the spleen on TD formation, we reviewed the presplenectomy (pre-S) and postsplenectomy (post-S) peripheral blood smears from 13 patients with AMM. The splenectomy was performed for a variety of reasons, including symptomatic hypersplenism or splenomegaly. The average number of TDs per 1,000 RBCs in the pre-S smears was 42 (range, 15 to 112 TDs), compared with 11 TDs in the post-S smears (range, 6 to 20 TDs)(P = less than .001). Only one of the 13 patients failed to exhibit this decrease in TDs post-S. There was no definite correlation between the number of TDs and the weight of the spleen removed at surgery, the interval since surgery, or age and sex of the patient. Based on this fourfold decrease in the number of TDs post-S, we conclude that the spleen in AMM play an important role in TD formation.

A 52-year-old man with agnogenic myeloid metaplasia had a sudden onset of pain and bleeding from the left ear and an associated decrease in hearing acuity on that side. Examination revealed a friable mass that filled the middle ear and protruded through a perforated tympanic membrane. Special staining of a tissue specimen of the mass revealed myeloid metaplasia. Otorhinolaryngologists should be aware of the fact that the ear can be involved in hematopoietic disorders.