Thrombocytosis and Thrombocythemia

Is It Possible to Predict Clonal Thrombocytosis in Triple-Negative Patients with Isolated Thrombocytosis Based Only on Clinical or Blood Findings?

JAK2, MPL, and CALR mutations define clonal thrombocytosis in about 90% of patients with sustained isolated thrombocytosis. In the remainder of patients (triple-negative patients) diagnosing clonal thrombocytosis is especially difficult due to the different underlying conditions and possible inconclusive bone marrow biopsy results. The ability to predict patients with sustained isolated thrombocytosis with a potential clonal origin has a prognostic value and warrants further examination. The aim of our study was to define a non-invasive clinical or blood parameter that could help predict clonal thrombocytosis in triple-negative patients. We studied 237 JAK2 V617-negative patients who were diagnosed with isolated thrombocytosis and referred to the haematology service. Sixteen routine clinical and blood parameters were included in the logistic regression model which was used to predict the type of thrombocytosis (reactive/clonal). Platelet count and lactate dehydrogenase (LDH) were the only statistically significant predictors of clonal thrombocytosis. The platelet count threshold for the most accurate prediction of clonal or reactive thrombocytosis was 449 × 10⁹/L. Other tested clinical and blood parameters were not statistically significant predictors of clonal thrombocytosis. The level of LDH was significantly higher in CALR-positive patients compared to CALR-negative patients. We did not identify any new clinical or blood parameters that could distinguish clonal from reactive thrombocytosis. When diagnosing clonal thrombocytosis triple-negative patients are most likely to be misdiagnosed. Treatment in patients with suspected triple negative clonal thrombocytosis should not be delayed if cardiovascular risk factors or pregnancy coexist, even in the absence of firm diagnostic criteria. In those cases the approach “better treat more than less” should be followed.

Etiologies of Extreme Thrombocytosis: A Contemporary Series

OBJECTIVE

To describe the multifactorial etiologies of extreme thrombocytosis (EXT) in different care settings and the frequency of finding an occult malignancy.

PATIENTS AND METHODS

We conducted a retrospective chart review at Mayo Clinic from January 1, 2011, through December 31, 2016. Adult patients who had at least 2 readings of platelet counts greater than 1000×10⁹/L within 30 days of each other were included. We determined the causes of EXT on the basis of preset definitions of precipitating factors and identified the dominant causes on the basis of the trend of platelet counts.

RESULTS

A total of 44,490 patients had thrombocytosis, and 305 patients (0.7%) had EXT. In 242 patients (79.3%), EXT was multifactorial. Surgical complications (54.1%) and hematologic malignancies (27.9%) were the 2 most dominant causes. Thirty-eight patients (12.5%) had new diagnoses of malignancies, mostly myeloproliferative neoplasms. In inpatients, surgical complications (71.9%), concurrent/previous splenectomy (50.5%), and infections (44.9%) were the most common causes, whereas hematologic malignancies (56.9%), iron deficiency (36.7%), and previous splenectomy (28.4%) were the most common causes in outpatients. Hematologic malignancy was 3.4 times more likely to be the cause of EXT in outpatients than in inpatients (56.9% vs 16.8%), and a new diagnosis of hematologic malignancy was 1.9 times more likely to be made in outpatients (15.6% vs 8.2%). Eighty-four percent of patients had resolution of EXT within 30 days. One patient died during the period of EXT. Nonsurgical patients with hematologic malignancies had the most prolonged period of EXT.

CONCLUSION

Extreme thrombocytosis is a multifactorial hematologic condition, and its etiology differs substantially between inpatients and outpatients. Occult hematologic malignancies are uncommon in EXT when other major causes are present.

The role of thrombocytapheresis in the contemporary management of hyperthrombocytosis in myeloproliferative neoplasms: A case-based review

Extreme thrombocytosis induces an acquired thrombotic-hemorrhagic diathesis, and left uncontrolled is a harbinger of potentially fatal vascular complications. Currently, cytoreduction with medical therapy remains the mainstay of hyperthrombocytosis management. However, it offers a less-than-ideal option in situations where a rapid reduction in platelets is urgently needed, as in the presence of vital end-organ ischemia or to ameliorate of life-threatening hemorrhage. The role of thrombocytapheresis, or plateletpheresis, in hyperthrombocytosis has become increasingly obsolete given the proactive titration of cytoreductive therapies and early identification and correction of reversible causes of reactive thrombocytosis. Despite its narrowed indications, plateletpheresis continues to offer a valuable temporizing measure in platelet count reduction before cytoreductive agents exert their maximal effect. In this context, it is important for the treating physician to be aware of the symptoms and risks associated with hyperthrombocytosis to inform best clinical practices. In this review, we discuss the role of plateletpheresis in the modern-day management of hyperthrombocytosis in patients with myeloproliferative neoplasms through a case based review of the literature. It becomes apparent throughout the discussion that the decision to perform plateletpheresis should be individualized based upon the clinical scenario, degree of thrombocytosis, available infrastructure and every patient's risk profile.

Acute Myocardial Infarction in a Patient with Essential Thrombocythemia Treated with Glycoprotein Ilb/Illa Inhibitor

Essential thrombocythemia (ET) rarely causes obstruction of coronary arteries or acute myocardial infarction. Treatment of acute myocardial infarction in patients with ET may be a problem due to the important role of platelets in the pathogenesis of infarction. There is no reported case of acute myocardial infarction with essential thrombocythemia treated with a glycoprotein lIb/Illa inhibitor. In this report, a 49-year-old woman with essential thrombocythemia, admitted with a diagnosis of acute inferolateral myocardial infarction, was treated with tirofiban, a glycoprotein IIb/IIIa receptor blocker.

Prognostic significance of preoperative C-reactive protein elevation and thrombocytosis in patients with non-metastatic renal cell carcinoma

PURPOSE

The aim of this study was to investigate the association of preoperative C-reactive protein (CRP) elevation and thrombocytosis with the prognosis of patients with non-metastatic renal cell carcinoma (RCC).

MATERIALS AND METHODS

This was a retrospective review of the medical records of 177 patients (130 men and 47 women) with non-metastatic RCC who underwent a radical nephrectomy between March 2000 and May 2008 and for whom preoperative CRP and platelet data were available for analysis. Preoperative CRP elevation and thrombocytosis were compared with clinical and pathological variables.

RESULTS

There were 38 patients with CRP elevation and 11 patients with thrombocytosis. The mean follow-up time was 48.3 months (median, 48.0; range, 13-111 months). Twenty-three patients (13.0%) developed metastases and six patients died during the follow-up period. CRP elevation was significantly correlated with anemia (p=0.001), T stage (p=0.004), grade (p=0.025), and metastasis (p<0.001). Thrombocytosis was significantly correlated with anemia (p=0.003), T stage (p=0.002), and metastasis (p=0.001). The univariate analysis identified anemia, CRP elevation, thrombocytosis, tumor histology subtype, tumor size, T stage, and grade as significant prognostic factors associated with recurrence-free survival, whereas the multivariate analyses showed that CRP elevation (p=0.033) and tumor size (p=0.007) were independent prognostic factors.

CONCLUSIONS

Preoperative CRP elevation and thrombocytosis were associated with a poorer prognosis and a higher recurrence rate in patients with non-metastatic RCC. Moreover, preoperative CRP elevation appeared to be an independent predictor of tumor recurrence and prognosis. Preoperative thrombocytosis, however, was not an independent prognostic factor for tumor recurrence and prognosis.

Non-ST-segment Elevation Myocardial Infarction in a Patient With Essential Thrombocythemia Treated With Glycoprotein IIb/IIIa Inhibitor

Essential thrombocythemia (ET) can cause systemic vascular thrombosis but rarely cause obstruction of coronary arteries or acute myocardial infarction (MI). Treatment of acute MI in patients with ET may be a problem due to the important role of platelets in the pathogenesis of infarction. In this report, a 63-year-old man presented with acute chest pain and a greatly increased platelet count. The patient was successfully treated with intravenous tirofiban, a glycoprotein IIb/IIIa receptor blocker. Essential thrombocythemia was diagnosed based on bone marrow findings, clinical presentation, and laboratory analysis. Thrombocythemia had been controlled with hydroxyurea.

Aortic thrombus in a patient with myeloproliferative thrombocytosis, successfully treated by pharmaceutical therapy: a case report

Introduction

Thrombosis in myeloproliferative thrombocytosis occurs usually in the microvessels and medium-sized arteries and veins and only rarely in the aorta. Aortic thrombosis is usually treated with thrombectomy. Reported here is a rare case that was treated pharmacologically.

Case presentation

A 60-year-old Japanese woman presented with numbness of both lower extremities. Her platelet count was 1787 × 10³/μl. Through bone marrow examination, we diagnosed her condition as myelodysplastic and/or myeloproliferative disorder-unclassifiable. Abdominal ultrasonography and computed tomographic scan revealed aortic thrombosis. Her platelet count was controlled with hydroxyurea and ranimustine. Aspirin and ticlopidine improved the numbness in both lower limbs on the second day. Aortic thrombosis was not observed in a computed tomographic scan on the seventh day.

Conclusion

For aortic thrombosis, surgical management is usually adopted, but pharmacological management is also an option because of its immediate curative effects.

The role of the Platelet Function Analyzer (PFA)-100 and platelet aggregometry in the differentiation of essential thrombocythemia from reactive thrombocytosis

INTRODUCTION

The most crucial component of all diagnostic criteria for essential thrombocythemia (ET) has been the exclusion of reactive thrombocytosis (RT). Our aim was to evaluate the diagnostic performance of the PFA-100 collagen-epinephrine (CEPI) cartridge test and epinephrine-induced aggregometry individually, but mainly combined, in the differentiation of ET from RT.

MATERIALS AND METHODS

26 patients with ET and 25 with RT were studied. Platelet function was analyzed by the PFA-100 and by light transmission aggregometry with epinephrine and ADP. The JAK2 mutational status was identified and hematological parameters, plasma von Willebrand factor antigen and activity levels were also assessed.

RESULTS

The sensitivity (Se), specificity (Sp), positive predictive value (PPV), and the negative predictive value (NPV) of PFA-100 CEPI vs epinephrine-induced aggregometry in the differentiation of ET from RT were estimated as follows: Se (%): 78.9 vs 84.6, Sp (%): 92.0 vs 96.0, PPV (%): 88.2 vs 95.7, NPV (%): 85.2 vs 85.7, respectively. When both of these methods were combined, a lower sensitivity of 68.4%, but a specificity of 100% was attained. The PPV observed with this double abnormal combination was 100% and the NPV 80.6%. Lastly, when we assessed the abnormality for either CEPI CT or epinephrine-induced aggregometry, the sensitivity was 100%, the specificity 88.0%, PPV 86.4% and NPV 100%. Thus, an abnormal combination was strongly suggestive of ET, while normal results with both methods excluded ET.

CONCLUSIONS

If our results are replicated by further studies, these two methods could be used very effectively as adjunct markers in the differentiation between ET and RT.

Defective plateletβ-N-acetyl hexosaminidase content and release in chronic myeloproliferative disorders

BACKGROUND AND OBJECTIVES

Abnormalities of platelet function or structure are a hallmark of chronic myeloproliferative disorders (MPD). In vivo platelet activation with the release of alpha- and delta-granules in the circulation is one of the most frequently described alterations in MPD. Platelets contain and release upon activation also lysosomes, and in particular beta-N-acetylhexosaminidase (Hex). We have assessed whether the content and in vivo release of Hex of platelets from MPD patients is altered.

DESIGN AND METHODS

Twenty-three MPD patients were compared with 19 age- and sex-matched healthy controls. The activity of platelet beta-N-acetylhexosaminidase was measured in plasma, serum and in the capillary blood emerging from the skin wound inflicted for the measurement of the bleeding time. Lysosome integral membrane protein (LIMP or CD63), lysosome-associated membrane protein (LAMP-2 or CD107b) and P-selectin were evaluated by flow cytometry. Platelet aggregation in vitro and the release of beta-N-acetylhexosaminidase, ATP and beta-thromboglobulin were performed to study platelet reactivity.

RESULTS

Hex levels in plasma were significantly higher in MPD than in controls while the release of Hex in the bleeding time blood, i.e. at a localized site of in vivo platelet plug formation, was lower in MPD and the platelet content of Hex was reduced. These changes were accompanied by in vivo platelet activation. Finally, the isoenzymatic pattern of Hex was altered in platelets of MPD patients, with a reduced amount of the Hex A isoform as compared with controls.b

INTERPRETATIONS AND CONCLUSIONS

MPD patients present an altered platelet Hex content and release; prospective studies to assess whether altered platelet Hex is related to thrombotic/hemorrhagic complications and/or tissue fibrosis in MPD are warranted.

Incidence and etiology of thrombocytosis in an adult Turkish population

The aim of the study was to determine the incidence and etiology of thrombocytosis in an adult Turkish population. The medical records of 2000 patients were reviewed retrospectively to determine (i) the etiology of elevated platelet counts, (ii) additional laboratory parameters (i.e., complete blood counts), and (iii) the presence of thromboembolic complications. Within 5 years, 174 678 platelet counts had been performed for 124,340 patients. Of the 124,340 patients, 2000 (1.6%; mean age, 55.2 +/- 17.4 years; range 16-94 years; male-to-female ratio, 3.6:1 [1570:430]) had one or more platelet counts of 500 x 10(3)/mm3 or higher during the study period. Secondary thrombocytosis was the most frequent cause of an elevated platelet count and occurred in 1934 cases (96.7%). Infection was the most common cause of secondary thrombocytosis, occurring in 1001 patients (50.1%). Compared with secondary thrombocytosis, primary thrombocytosis was significantly associated with a higher rate of thromboembolic complications. It is concluded that a high platelet count may have both diagnostic and therapeutic implications. Secondary thrombocytosis is a common finding and mostly secondary to infection. Primary thrombocytosis has a higher risk for thromboembolic events than does secondary thrombocytosis.

Essential thrombocythemia: a review of diagnostic and pathologic features

CONTEXT

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder (CMPD) characterized predominately by thrombocytosis and abnormal megakaryocyte proliferation. The current diagnostic criteria require a combination of clinical, histologic, and cytogenetic data. The diagnosis relies largely on exclusion of other causes of thrombocytosis.

OBJECTIVE

Describe historical, clinical, and laboratory features of ET in order to understand, clarify, and more accurately diagnose this entity.

DATA SOURCES

Review contemporary and historical literature on ET and other causes of thrombocytosis.

CONCLUSIONS

ET is a relatively indolent and often asymptomatic CMPD that is characterized primarily by a sustained elevation in platelets > or = 600 x 10(3)/microL (> or = 600 x 10(9)/L), proliferating enlarged and hyperlobated megakaryocytes, and minimal to absent bone marrow fibrosis. Significant changes and revisions to the diagnostic requirements and criteria for ET have occurred during the last 30 years. Recently, a mutation in the Janus kinase 2 (JAK2) gene has been found in a significant number of cases of ET and other CMPDs. In up to 57% of ET cases, a mutation in the JAK2 gene can be detected. In the absence of a JAK2 mutation and features of another CMPD, the diagnosis of ET remains a diagnosis of exclusion after other causes of thrombocytosis have been excluded.

Multiple coronary thrombosis and stent implantation to the subtotally occluded right renal artery in a patient with essential thrombocytosis: A case report with review

Essential thrombocytosis is a myeloproliferative disorder of unknown etiology manifested clinically by the overproduction of platelets in the absence of a definable cause. Platelet dysfunction in essential thrombocytosis results in both hemorrhage and thrombosis. It is one of the rare causes of ischemic cardiovascular events. Fewer than 20 cases of essential thrombocytosis with involvement of coronary arteries leading to acute coronary syndromes or myocardial infarction have been reported. We report a case of multiple coronary thrombosis involving the left anterior descending artery and circumflex artery and stent implantation to the subtotally stenotic right renal artery in a women with unstable angina pectoris, essential thrombocytosis and previous history of renal artery trombosis.

Thrombocytosis after trauma: incidence, aetiology, and clinical significance

BACKGROUND

Our aim was to assess the occurrence, aetiology, and clinical significance of a platelet count greater than 600 x 10(3)/mm(3) in trauma patients.

METHODS

All trauma patients admitted to the intensive care unit (ICU) during a 13-month period were prospectively studied. Platelet counts were performed daily. We recorded the patient's age, sex, nature of trauma, severity of illness scores, episodes of infections in the ICU, acute lung injury, bleeding, and thromboembolic events. Patients with thrombocytosis were also followed during their hospital stay and 1 month after hospital discharge.

RESULTS

A total of 176 patients were included. Thrombocytosis developed in 36 patients (20.4%) at a mean (sd) time of 14.0 (4.0) days and the platelet count normalized 35.0 (13.0) days after admission to the ICU. All patients with thrombocytosis had one or more possible predisposing conditions before the occurrence of thrombocytosis: nosocomial infection occurred in 30 patients (83%), acute lung injury in 17 (47%), bleeding in 27 (75%), and administration of cathecholamines in 24 (67%). Three venous thromboembolic complications occurred in the ICU (1.7%) and one during follow-up. Only one patient presented thrombocytosis at the time of diagnosis. Despite the fact that patients with thrombocytosis had a greater severity of illness, the ICU mortality was comparable among patients with and without thrombocytosis (8 vs 14%, P=0.34).

CONCLUSIONS

Reactive thrombocytosis is a common finding after severe trauma and was found to be associated with a better survival than predicted by severity of illness score. Unless additional risk factors are present, reactive thrombocytosis is not associated with an increased risk of thromboembolic events.

Significance of thrombocytosis for determining prognosis in patients with localized renal cell carcinoma

OBJECTIVES

To evaluate the significance of thrombocytosis for determining survival in patients with localized renal cell carcinoma (RCC) who underwent radical nephrectomy with curative intent.

METHODS

The study population comprised 151 patients who underwent radical nephrectomy with a diagnosis of localized RCC. The inclusion criteria were at least one preoperative platelet count and a tissue diagnosis of RCC. Thrombocytosis was defined as a platelet count greater than 400,000/mm3. The charts of these patients were retrospectively reviewed and the relationship between the preoperative platelet counts and survival was evaluated according to the histologic variants.

RESULTS

The mean follow-up was 37.1 +/- 24.1 months (median 34, range 3 to 91). Of these 151 patients, 21 had a preoperative platelet count greater than 400,000/mm3. The thrombocytosis rate was significantly greater in those with advanced T stage (P = 0.045). Lymph node positivity also correlated with thrombocytosis (P = 0.028). However, no statistically significant correlation was found between grade and histologic subtypes and thrombocytosis (P = 0.053 and P = 0.354, respectively). Ten (47.6%) of 21 patients with thrombocytosis and 21 (16.2%) of the remaining 130 patients died of disease progression (P = 0.002). The Kaplan-Meier cause-specific survival curves showed that patients who had thrombocytosis had a mean survival of 45.2 months compared with 76.6 months in patients without thrombocytosis (P = 0.0002).

CONCLUSIONS

Preoperative thrombocytosis is a significant predictor for determining prognosis in patients with localized RCC. Thrombocytosis was found more frequently in patients with advanced stage RCC, and patients with preoperative thrombocytosis had a worse survival compared with those with normal platelet counts.

Essential thrombocytosis causing a massive myocardial infarction

Essential thrombocytosis (ET) is an uncommon myeloproliferative disorder. This disease may have both occlusive thrombotic as well as hemorrhagic complications throughout the body. We report a young man with severe thrombocytosis, clinically thought to be unknown ET, who had massive myocardial infarction requiring bypass surgery, ventricular assist device and ultimately cardiac transplantation. ET may have devastating cardiovascular consequences and should be considered as a rare cause of myocardial infarction in the young.

Hantavirus infection in people inhabiting a highly endemic region of the Gran Chaco territory, Paraguay: association with Trypanosoma cruzi infection, epidemiological features and haematological characteristics

The seroprevalences of anti-hantavirus antibodies were determined in 712 individuals (551 Indians, 140 Mennonites of German ancestry, and 21 Paraguayans of Spanish ancestry) inhabiting a region of western Paraguay in the Gran Chaco territory of South America. The overall seroprevalence of hantavirus infection among the 712 subjects, who were aged 2-80 years, was 42.7% (45.2% in the Indians and 34.2% in the non-Indians). Of the 672 subjects also checked for antibodies against Trypanosoma cruzi, 226 (33.6%) were seropositive for this protozoan parasite. The results of a multivariate regression analysis indicated that, after adjusting for age, sex, setting of residence (rural/urban) and infection with the human T-cell leukaemia/lymphoma virus type II (HTLV-II), a T. cruzi-seropositive individual was 1.73 times more likely to be hantavirus seropositive than a T. cruzi-seronegative individual. Living in a rural setting increased the risk of being hantavirus seropositive 2.17-fold. In both the Indians and non-Indian subpopulations, hantavirus seroprevalence increased with age in both sexes, but only in the non-Indian supopulation was this increase significantly greater in males than in females. Hantavirus seropositivity was significantly associated with thrombocytosis, even after adjusting for the relevant confounders.

Levels of serum cytokines and acute phase proteins in patients with essential and cancer-related thrombocytosis

Essential thrombocytosis (ET) is a myeloproliferative disorder resulting in an increased production of abnormal platelets. Reactive thrombocytosis (RT) is occasionally observed in clinical situations including chronic inflammation and malignancy. The aim of the present study was to evaluate the discriminatory efficiency of various laboratory tests in patients with ET and cancer-related RT. Forty-five patients with ET, 52 patients with RT, and 25 age-matched normal individuals comprised the study population. Plasma interleukin-1 alpha (IL-1a), IL-2, IL-6, tumor necrosis factor alpha (TNF-a), platelets, hematocrit, hemoglobin, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), lactate dehydrogenase (LDH) and ferritin were determined. We found increased levels of ferritin, LDH, CRP, ESR, IL-1a, and IL-6 in RT compared with ET (p < 0.01 to p < 0.0005). Hemoglobin, hematocrit, and platelets were significantly lower in RT than in ET (p < 0.0005). Furthermore, ferritin and ESR were negatively correlated with Hct, hemoglobin, and TNF-a, whereas ferritin was positively correlated with ESR, IL-1a, IL-6, and CRP, and IL-1a was positively correlated with IL-6. We consider that the aforementioned parameters should be included in the investigation of unexplained thrombocytosis for the differentiation of essential from cancer related thrombocytosis.

Extreme thrombocytosis as a sign of coeliac disease in the elderly: case report

Increase in the number of blood platelets to over 1,000,000/mm3 in elderly patients is generally considered secondary to a myeloproliferative or neoplastic disease. To report the case of an elderly woman hospitalized for extreme thrombocytosis associated with severe anaemia, who was found to be suffering from coeliac disease. The patient, aged 83 years, was hospitalized presenting with fatigue. Laboratory tests showed microcytic hypochromic anaemia (haemoglobin 4 g/dl) and extreme thrombocytosis (platelet count 1,400,000/mm3). Physical examination was normal, with the exception of marked thinness. There was no evidence of macroscopic bleeding from the gastrointestinal or genitourinary tracts. She had never suffered from gastrointestinal problems and had no family history of gastroenterological diseases. Oesophagogastroduodenoscopy and histology of the gastric and duodenal mucosa evidenced atrophic gastritis and an adenomatous polyp. The duodenal mucosa showed total villous atrophy, suggesting the diagnosis of coeliac disease. Antiendomysial IgA and anti-transglutaminase IgA antibodies were also positive. Colonoscopy was negative. An ultrasound examination of the abdomen was normal, and the spleen was within the normal range. A peripheral blood smear showed no alterations in erythrocyte morphology typical of hyposplenism due to coeliac disease. The platelet count decreased rapidly after blood transfusions, when both serum iron and ferritin levels were still below normal limits. Furthermore, we observed a significant inverse correlation between the platelet count and haemoglobin concentration (r = -0.94, P < 0.003). Platelet count and red blood cell count normalized after 2 months of a gluten-free diet; the haemoglobin concentration was also normal at this time. After 1 year of following a gluten-free diet, the patient remained well and had no complaints. There were no gastrointestinal disturbances. All haematological parameters were within normal limits. Intestinal biopsies showed normal villi and crypts without inflammatory infiltration of the lamina propria. This case shows that the association of haematological signs--extreme thrombocytosis and severe anaemia--considered in an elderly patient to be typical of myeloproliferative disorders or neoplastic conditions can be due to coeliac disease; thus, coeliac disease must also be considered among the possible diagnoses.

Serum proinflammatory cytokines and its relationship to clinical parameters in lung cancer patients with reactive thrombocytosis

Proinflammatory cytokines Interleukin-1 beta (IL-1 beta) and Interleukin-6 (IL-6) play a significant role in the pathogenetic processes related to various malignant and inflammatory conditions. Leukocytosis, thrombocytosis and increased acute phase protein levels are part of a systemic inflammatory response. In this study, we measured the concentrations of IL-1 beta, IL-6 and ferritin as well as hemoglobin, lactate dehydrogenase (LDH), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in 23 patients (male 15, female 8, median age 68 years) with lung cancer and reactive thrombocytosis (LCRT), in 27 (male 18, female 9, median age 64 years) with benign inflammatory lung disorder (BILD) and 18 (male 10, female 8, median age 62 years) lung cancer patients with a normal platelet count (LCNP). IL-1 beta levels were significantly higher in the three patient groups in comparison with control subjects (P < 0.001) but without significant difference among the three patient groups. IL-6 was higher in all three patients groups but only in the BILD group it was significantly higher than the control group (P < 0.05). However, no significant difference in IL-6 serum levels was found between the two lung cancer groups. CRP and LDH were significantly higher in the LCRT group in comparison with the other two patient groups (P < 0.01 and 0.001, respectively), while ferritin was higher in both lung cancer groups in comparison with the BILD group (P < 0.001). Our data suggest that in lung cancer patients, reactive thrombocytosis is part of the systemic inflammatory reaction for which IL-1 beta and IL-6 may be intermediate but not independent mediators.

Aortic mural thrombus embolization: an unusual presentation of essential thrombocytosis

Hypercoagulable conditions are increasingly recognized as a causative factor in patients with thromboembolic phenomenon. Essential thrombocytosis (ET) is one such condition. This particular myeloproliferative disorder is most commonly associated with thrombotic complications of the microvasculature and bleeding complications involving mucosal surfaces (e.g., gastrointestinal tract bleeding). This case identifies an uncommon manifestation of ET-aortic mural thrombus leading to visceral embolism. Vascular surgeons should be aware of the diagnosis, treatment, and complications of ET, as patients with this condition may first present with an arterial occlusion.

The role of blood component removal in essential and reactive thrombocytosis

An elevated platelet count is now a common finding in both hospitalized and ambulatory patients with the advent of automated complete blood cell counters. Clinicians may be called upon to make a distinction between a reactive process and a primary hematologic disorder as the cause of a thrombocytosis and to determine whether treatment is indicated. Essential thrombocythemia and other myeloproliferative disorders may present with marked increases in the platelet counts and may be associated with thrombohemorrhagic complications. Reactive thrombocytosis can be caused by iron deficiency and a variety of inflammatory conditions, infections, malignancy, bleeding or hemolysis, splenectomy, and drugs. Acute therapy for all of these disorders has included blood component removal, specifically plateletpheresis. The role of plateletpheresis in current management of thrombocytosis is considered, based on current knowledge of pathophysiology and a review of the literature.

Relation of serum 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) level to hematological examination results in veterans of Operation Ranch Hand

The authors studied indices of hematologic function and exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in Vietnam War veterans of Operation Ranch Hand--the Air Force unit responsible for the aerial spraying of Agent Orange and other herbicides in Vietnam. The herbicides were contaminated with TCDD. The authors measured TCDD serum levels in 1987 or later and extrapolated the result to the time of service in Vietnam. The authors studied serum TCDD level in relation to red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, white blood cell count, platelet count, and erythrocyte sedimentation rate at each of 4 physical examinations. Compared with veterans not involved in Operation Ranch Hand, those with the highest TCDD levels in Operation Ranch Hand had mean corpuscular volumes that were about 1% higher and platelet counts that were about 4% higher. These small increases were unlikely to be of clinical significance and may not have been caused by TCDD.

Medical management of a large aortic thrombus in a young woman with essential thrombocythemia

Aortic thrombus formation is rare in the patients with essential thrombocytosis (ET); therefore, no guidelines for its management have been established. Embolism from ET-associated large vessel thrombi is potentially lethal and has been managed surgically in a few reported cases. We describe herein a 45-year-old black woman with ET found to have a 3.5-cm, pedunculated intra-aortic thrombus at the thoracoabdominal junction. How to treat this potentially devastating aortic thrombus was a management dilemma. We believed, based on the patient's diagnosis of ET and the histology of similar thrombi in 1 reported series, that the aortic thrombus was a "white thrombus" consisting primarily of aggregated platelets with a minimal fibrin network and almost no entrapped erythrocytes. The patient was treated with aspirin, 325 mg daily, as a platelet antiaggregating agent and hydroxyurea, 1,500 mg daily, to reduce the platelet count to less than 450 x 10(9)/L. The thrombus resolved without severe thromboembolic events. To our knowledge, this is the first reported case of a large intra-aortic thrombosis associated with ET that has been successfully managed with medical therapy alone.

Abnormalities of platelet aggregation in chronic myeloproliferative disorders

A large variety of platelet dysfunctions has been described in chronic myeloproliferative disorders. These abnormalities may be due to deficiency of platelet granules, arachidonic acid metabolism defects or platelet membrane glycoproteins abnormalities. In this study we intend to detect the incidence of platelet function defects in 76 patients with various types of chronic myeloproliferative disorders. The platelet activity was studied in vitro by measuring platelet aggregation in response to ADP, epinephrine, collagen, arachidonic acid and ristocetin. These results were subsequently correlated with bleeding time and clinical aspects (bleeding or thrombosis). We found complex changes in platelet response with all agonists, in varied proportions. These abnormalities include absent, decreased or abnormal platelet aggregation response. In a few cases we found a markedly decreased, almost absent platelet response to all agonists while in some patients a normal platelet aggregation was noted. The correlation between these results and template bleeding time, thrombotic or hemorrhagic events and the type of diseases was difficult to establish and sometimes conflictual. Despite this fact, we consider that investigating platelet aggregation may be useful not only for the assessment of the hemostatic balance in chronic myeloproliferative disorders but also for a better insight into cell abnormalities occurring in these pathologic conditions.

Artefactual serum hyperkalaemia and hypercalcaemia in essential thrombocythaemia

AIM

To investigate possible abnormalities of serum potassium and calcium levels in patients with essential thrombocythaemia and significant thrombocytosis.

METHODS

24 cases of essential thrombocythaemia with significant thrombocytosis (platelet count > 700 x 10(9)/litre) had serum potassium and calcium estimations performed at the time of maximum thrombocytosis before treatment, and at the time of low platelet count after treatment with cytoreductive drugs. Selected patients were further investigated with plasma sampling and estimation of ionised calcium and parathyroid hormone.

RESULTS

At the time of maximum thrombocytosis six patients had serum hyperkalaemia (> 5.5 mmol/litre) and five had serum hypercalcaemia (> 2.6 mmol/litre). Following treatment and reduction of the platelet count, hyperkalaemia resolved in all cases and hypercalcaemia in four of the five cases. Mean serum potassium and calcium concentrations were raised (p < 0.0001) at maximum thrombocytosis compared with the values when the platelet count was low. Serum potassium and calcium values were significantly correlated at all stages. Measurements on plasma consistently corrected the hyperkalaemia but not the hypercalcaemia. Serum hypercalcaemia was associated with raised ionised calcium and normal parathyroid hormone concentrations.

CONCLUSIONS

Essential thrombocythaemia with significant thrombocytosis is associated with serum hyperkalaemia and hypercalcaemia. The probable mechanism of hypercalcaemia is the secretion of calcium in vitro from an excessive number of abnormally activated platelets. It is thus likely that the hypercalcaemia is an artefact, as is the hyperkalaemia.

Circulating levels of thrombopoietic and inflammatory cytokines in patients with clonal and reactive thrombocytosis

The regulation of megakaryocytopoiesis and thrombopoiesis appears to be under the control of an array of hematopoietic growth factors. To determine the relationship between endogenous cytokine levels and circulating platelet counts, we measured the serum levels of both thrombopoietic and inflammatory cytokines in the peripheral blood and bone marrow samples from 70 patients with clonal thrombocytosis (CT) caused by myeloproliferative disorders, 28 patients with reactive thrombocytosis (RT), and 35 normal control subjects. The levels of thrombopoietin (TPO), interleukin-6 (IL-6), soluble IL-6 (sIL-6) receptor, IL-11, stem cell factor (SCF), IL-3, and IL-8 were determined by enzyme-linked immunosorbent assay (ELISA). Platelet counts were significantly higher in both CT and patients with RT (699+/-399x10(9)/L, P<.001; 642+/-200 x 10(9)/L, P<.001; respectively) as compared with the normal control subjects (240+/-47x10(9)/L). The concentrations of cytokines in the bone marrow correlated well with those in the peripheral blood. The endogenous levels of TPO, IL-6, and sIL-6 receptor were significantly higher in both CT and patients with RT than those in normal control subjects. The median level of IL-6 was significantly higher in patients with RT than in patients with CT (40 pg/mL vs. 5 pg/mL; P<.001); however, there was no detectable difference in TPO and sIL-6 receptor levels between the two groups. Significantly higher levels of SCF and IL-8 were also found in patients with CT as compared with those found in normal control subjects (median 2460 pg/mL vs 1995 pg/mL, P<.05; 20 ng/mL vs. 5 ng/mL, P = .001; respectively). Finally, IL-11 and IL-3 levels were undetectable in most patients with thrombocytosis. Our results reveal that the endogenous levels of TPO, IL-6, sIL-6 receptor, IL-8, and SCF are elevated in patients with CT or RT. These cytokines appear to be active mediators involved in the regulation of thrombopoiesis during clonal and reactive thrombocytosis.

Aetiology and clinical significance of thrombocytosis: analysis of 732 patients with an elevated platelet count

OBJECTIVE

To determine the aetiology and clinical significance of an elevated platelet count (thrombocytosis) in a large cohort of patients.

DESIGN

A retrospective review of the medical records was performed on all patients, who had at least one platelet count > or = 500 x 10(9) L-1.

SETTING

Departments of Medicine and Surgery, University of Ulm, Germany.

SUBJECTS

A total of 732 patients with thrombocytosis.

MAIN OUTCOME MEASURES

Classification of thrombocytosis and thromboembolic complications, and evaluation of laboratory parameters distinguishing between primary and secondary thrombocytosis.

RESULTS

Of the total of 732 patients, 89 (12.3%) had primary and 643 (87.7%) had secondary thrombocytosis. Essential thrombocythaemia was observed in 40 of 89 patients (45%) with primary thrombocytosis. The most frequent causes of secondary thrombocytosis were tissue damage (42%), infection (24%), malignancy (13%) and chronic inflammation (10%). Primary thrombocytosis was significantly associated with a higher platelet count and an increased incidence of both arterial and venous thromboembolic complications. In secondary thrombocytosis, thromboembolic events were restricted to the venous system and occurred only in the presence of other risk factors. Mean values of leucocyte count, haematocrit, erythrocyte sedimentation rate, fibrinogen, serum potassium and lactate dehydrogenase were significantly different in primary and secondary thrombocytosis.

CONCLUSIONS

The finding of an elevated platelet count on routine blood examination has diagnostic, prognostic and therapeutic implications. It is of clinical importance to distinguish between primary and secondary thrombocytosis, as thrombotic complications occur more frequently in primary thrombocytosis. Unless additional risk factors are present, secondary thrombocytosis is not associated with a significant risk for thromboembolic events.

Acute coronary occlusion and in-stent thrombosis in a patient with essential thrombocythemia

We describe a case of essential thrombocythemia in a 34-year-old male who presented with acute anterior wall myocardial infarction and a platelet count of 2,100,000/mm3. Primary percutaneous coronary angioplasty and stenting were performed. Postangioplasty course was complicated by stent thrombosis requiring repeat coronary angioplasty and persistent femoral arterial bleeding that was treated with surgical exploration and repair. The patient was subsequently treated with platelet pheresis, acetylsalicylic acid, ticlopidine, hydroxyurea, and anagrelide without further complications.

Thrombotic complications in essential thrombocythemia with relatively low platelet counts

Essential thrombocythemia (ET) is often associated with thrombotic and hemorrhagic complications, mostly at platelet counts exceeding 600 x 10(9)/L. There are, however, a few reports of such complications in ET at considerably lower platelet levels and the therapeutic approach to affected patients with relatively low platelet counts is still controversial. In the present study, the first to directly address the issue of hemostatic manifestations at relatively low platelet counts, we have determined the lowest platelet counts associated with such manifestations in 56 consecutive ET patients. Clinical manifestations related to ET were recorded in 46 (82%) patients. Of the symptomatic patients, 32 (70%) had symptoms at platelet counts lower than 600 x 10(9)/L, 23 (50%) at counts lower than 500 x 10(9)/L, 10 (22%) at counts lower than 400 x 10(9)/L, and 6 patients (13%) at platelet counts as low as 300-350 x 10(9)/L. Severe complications occurred at platelet counts lower than 600 x 10(9)/L in 10 patients (22%), lower than 500 x 10(9)/L in 7 (15%), and at lower than 400 x 10(9)/L in 2 (4%). Thrombotic neurologic symptoms were the most common (31 patients, 67%), followed by peripheral vascular symptoms (17 patients, 37%); hemorrhagic complications were relatively rare (3 patients, 7%). In most cases, cessation or improvement of clinical manifestations was observed only after further reduction in platelet counts. In conclusion, thrombotic manifestations, including severe ones, are not uncommon in ET at relatively low platelet counts. We recommend that symptomatic patients with relatively low platelet counts be treated and the platelet counts further reduced well into the lower normal range.

Thiotepa for the treatment of thrombocythemia in patients with Philadelphia chromosome positive chronic myelogenous leukemia

BACKGROUND

Patients with chronic myelogenous leukemia (CML) occasionally experience persistent thrombocythemia despite having adequate white blood cell (WBC) counts. Trimethylenethiophosphoramide (thiotepa) is an alkylating agent that significantly inhibits platelet production.

METHODS

The authors studied the effects of thiotepa in eight patients with CML with persistent thrombocythemia. All patients had adequate WBC counts while receiving therapy for leukemia. The median age of the patients was 58 years, and all had received at least 2 prior therapy regimens for CML. Thiotepa was administered by intravenous infusion at a dose of 75 mg/m2 once every 2 to 3 weeks; doses were adjusted according to hematologic response.

RESULTS

Seven patients were evaluable for response to thiotepa. Their pretreatment median platelet count was 1215 x 10(9)/L. After receiving the first dose, 6 patients (86%) had favorable responses as the median platelet count dropped to 348 x 10(9)/L (P = 0.02). However, all the patients' platelet counts returned to near baseline values after the first course. Patients required a median of three courses to achieve stable platelet counts near the normal range. In 4 patients (57%), administration of thiotepa was discontinued because of a stable normal platelet count after a median of 7.5 courses; 1 patient was still receiving treatment at last follow-up (18 courses) and 2 patients stopped receiving treatment after their disease progressed to the blastic phase. Toxicity was mostly hematologic, with neutropenia (< or = 1 x 10(9)/L) occurring during 5 of the 64 courses (8%) administered but only 1 patient's course was complicated by fever.

CONCLUSIONS

The authors conclude that thiotepa is useful in controlling thrombocythemia in CML patients who have elevated platelet counts despite having adequate WBC counts.

Idiopathic primary osteo-myelofibrosis: a clinico-pathological study on 208 patients with special emphasis on evolution of disease features, differentiation from essential thrombocythemia and variables of prognostic impact

A retrospective clinico-pathological study was performed on 208 consecutively recruited patients (94 males, 114 females, median age 67 years) with idiopathic (primary) osteo-/ myelofibrosis (IMF). According to bone marrow histology (cellularity) as well as extent (semiquantitative grading) and quality (reticulin/collagen) of myelofibrosis, stages of the disease process were determined. At closure of this study (observation time 65 months) 133 patients were dead and 75 alive and median survival was 56 months. The wide spectrum of clinical signs and symptoms and laboratory data on admission was reflected by a corresponding variety of histological features. Significant differences of hematological values could be calculated between patients with or without early reticulin fibrosis (fiber scores 0 and 1) and advanced fibro-osteosclerotic stages (fiber scores 2 and 3). Evolution of disease features was elicited by longitudinal follow-up studies and sequential bone marrow biopsies. Morphometric assessment of fiber density in patients without preceding chemotherapy revealed an unpredictable and varying progression of myelofibrosis associated with alterations of certain laboratory parameters (hemoglobin level, spleensize, thrombocytosis). Differentiation from essential (primary) thrombocythemia (ET) was required in 25 patients who fulfilled the postulated diagnostic criteria. In fact, this group was consistent with hypercellular, early stages of IMF without relevant reticulin fibrosis and an excessively raised platelet count (> or = 1000 x 10(9)/1). Discrimination was only feasible by regarding histology carefully, particularly abnormalities of megakaryopoiesis and follow-up data. Parameters of predictive value indicating a significant loss in life expectancy in comparison with a sex- and age-adjusted normal population included: age (> or = 60 years), hemoglobin levels (< or = 10 g/dl), thrombocyte count (< or = 600 x 10(9)/1) and the presence of myeloblasts and promyelocytes. Statistical analysis disclosed that in the so-called early stages of IMF without relevant myelofibrosis, findings indicative for extramedullary hemopoiesis or generalization of the disease process exerted an unfavourable influence on survival.

Reduction of antithrombin III, protein C, and protein S levels and activated protein C resistance in polycythemia vera and essential thrombocythemia patients with thrombosis

Patients with polycythemia vera (PV) or essential thrombocythemia (ET) show a high frequency of thrombosis. The reduction of hematocrit after phlebotomy and normalization of platelet counts do not completely eliminate thrombotic risk. Some preliminary studies reported a reduction in the concentration of natural anticoagulants (NA) in this group of patients. For this reason we evaluated protein S (PS) total antigen, antithrombin III (AT III), and protein C (PC) activity in 81 patients with chronic myeloproliferative disorders (33 with PV and 48 with ET). Data were compared with those obtained in 70 healthy sex- and age-matched subjects. Fifty-seven percent of patients (46 out of 81) showed one or more thrombotic episodes at diagnosis or during follow-up. Interestingly, we found a NA deficit in 43.5% of patients with thrombosis versus only 5.7% in the group of patients without thrombosis. These results may suggest new interpretations about the pathogenesis of thrombosis in PV or ET patients.

Acute myeloid leukemia evolving from essential thrombocythemia in two patients treated with hydroxyurea

Essential thrombocythemia (ET) is an uncommon myeloproliferative disorder, which is thought to develop from a multipotent stem cell. Like other myeloproliferative diseases, ET is associated with an increased risk of development of acute leukemia (AL). However, the large majority of cases of leukemic transformation in ET are thought to be related to prior therapy, usually radioactive phosphorous or alkylating chemotherapy, and the development of AL in ET is extremely rare in the untreated patient. In this report, two cases of ET which evolved into AL without prior exposure to radiation or alkylating agents, and which were treated with long-term hydroxyurea therapy, are described. The first case had cytogenetic changes in the bone marrow suggestive of therapy-associated leukemia, and the second developed myelodysplastic syndrome on therapy which was likely chemotherapy-induced and led to acute leukemia. Prolonged used of hydroxyurea in patients with ET may lead to therapy-associated acute leukemia.

Treatment of essential thrombocythemia with anagrelide

Essential thrombocythemia (ET) is a myeloproliferative disorder characterized by persistent elevation in platelet count. It is a rare disorder in children, and children who have symptoms require treatment. We report the successful use of anagrelide, with few toxic effects, in the treatment of three children with ET.

Plasma interleukin-6 and C-reactive protein levels in reactive versus clonal thrombocytosis

PURPOSE

Evaluate the discriminatory value of plasma interleukin-6 or C-reactive protein levels in clonal thrombocytosis compared with those in reactive thrombocytosis.

PATIENTS AND METHODS

A comparative analysis of quantitatively measured laboratory values in a prospectively studied group of consecutive patients. The setting was a tertiary referral center consisting of two hospitals and an outpatient clinic. Plasma interleukin-6 and C-reactive protein levels were measured in 91 consecutive patients with thrombocytosis (platelet count > or = 600 x 10(9)/L). The cause of thrombocytosis was determined by reviewing the medical histories and follow-up data without knowledge of the corresponding laboratory values. Sixty-four patients had reactive thrombocytosis, 20 had clonal thrombocytosis, and 7 had clonal thrombocytosis plus reactive thrombocytosis. Plasma interleukin-6 was measured by an enzyme-linked immunosorbent assay, and C-reactive protein was measured with rate immunonephelometry.

RESULTS

Interleukin-6 levels were undetectable in all the patients with clonal thrombocytosis, whereas they were increased in 60% of the patients with reactive thrombocytosis or clonal thrombocytosis plus reactive thrombocytosis. There was a correlation between interleukin-6 and C-reactive protein levels (r = .6), and the median and range values of both levels differed significantly between the clonal thrombocytosis group and the other two groups (P < 0.0001). In 81% of the patients with reactive thrombocytosis, levels of either interleukin-6 or C-reactive protein were elevated. There was no correlation between interleukin-6 and C-reactive protein levels and the platelet count.

CONCLUSIONS

An elevated interleukin-6 level is rare in uncomplicated clonal thrombocytosis and suggests reactive thrombocytosis. However, an isolated normal value has little discriminatory value. Measurement of C-reactive protein level may be used as a less expensive surrogate for measurement of interleukin-6. Repeatedly low levels of both interleukin-6 and C-reactive protein are most consistent with clonal thrombocytosis.

Issues in the diagnosis and management of essential thrombocythemia

OBJECTIVE

To summarize the current trends in the diagnosis and management of essential thrombocythemia (ET) and to discuss the treatment of young and pregnant patients with ET.

DESIGN

We review our experiences in the diagnosis and management of ET.

MATERIAL AND METHODS

A definitive diagnosis of ET at initial examination is seldom possible because of the low incidences of associated clonal cytogenetic abnormalities and palpable splenomegaly. The criteria of the Polycythemia Vera Study Group for the diagnosis of ET are provided, as are the clinical and laboratory features that help to distinguish ET from reactive thrombocytosis.

RESULTS

Patients with ET have an almost normal life expectancy if thrombohemorrhagic complications are controlled. Although a previous history of thrombosis is an established risk factor for further episodes, the adverse effects of extreme thrombocytosis and age are less well defined. Determining which patients require therapy is controversial. The management of young or pregnant patients necessitates special considerations.

CONCLUSION

Until additional data become available, no strong recommendations can be given in support of or against specific therapy for asymptomatic young patients. We favor treatment in asymptomatic patients with cardiovascular risk factors but not in asymptomatic women who are pregnant or are of childbearing age.

Occurrence, etiology, and clinical significance of extreme thrombocytosis: a study of 280 cases

PURPOSE

To determine the etiology and to evaluate the clinical consequences of an extremely elevated platelet count.

PATIENTS AND METHODS

A review of the medical records was performed on all patients encountered during a 5 1/2-year period who had at least one platelet count of 1,000 x 10(9)/L or greater.

RESULTS

Of the total of 280 patients with extreme thrombocytosis (EXT), 231 (82%) had reactive thrombocytosis (RT), 38 (14%) had a myeloproliferative disorder (MPD), and 11 (4%) had cases of uncertain etiology. RT was more common than MPD in all age groups except those in the eighth decade and older. Symptoms of bleeding and/or vaso-occlusive phenomena were noted in association with EXT in 21 (56%) of the MPD patients but in only 10 (4%) of the RT patients. Treatment to lower the platelet count and/or inhibit platelet function was employed in 36 MPD patients and 23 RT patients. Eight patients with MPD and 34 with RT are known to have died, but no patient in either group is known to have died of a thrombotic or bleeding event when the platelet count was greater than or equal to 1,000 x 10(9)/L.

CONCLUSIONS

Platelet counts greater than or equal to 1,000 x 10(9)/L should not be considered rare events in the general, acute-care hospital population, and usually represent a reactive phenomenon.

Combined plateletpheresis and cytotoxic chemotherapy for symptomatic thrombocytosis in myeloproliferative disorders

BACKGROUND

Patients with myeloproliferative disorders (MPD) may have symptomatic thrombocytosis develop that requires prompt and sustained lowering of platelet counts to avert serious thrombotic or hemorrhagic sequelae.

METHODS

The authors retrospectively studied the short- and long-term effects of plateletpheresis combined with three different chemotherapy regimens (busulfan, hydroxyurea, or busulfan/hydroxyurea) in 30 patients with MPD with symptomatic thrombocytosis.

RESULTS

Twenty-nine patients entered first remission (FR) with initial treatment. The average number of plateletphereses to FR was three (standard deviation [SD], +/- 3). Average total dose of busulfan (216 mg) and time to FR (1.6 months) were less than for previously reported patients treated without plateletphereses. Addition of hydroxyurea to busulfan decreased the number of plateletpheresis needed (P = 0.02) but did not additionally reduce the amount of busulfan needed or the time to FR. The shortest time to FR was in the hydroxyurea group (mean, 0.6 +/- 0.3 months), but unmaintained remission could be achieved only in the busulfan-treated groups. With median follow-up of 68 months, median survival was 53 months for the busulfan group, 55 months for the hydroxyurea group, and was undefined with no deaths for the busulfan/hydroxyurea group. Neither fatal complications of recurrent symptomatic thrombocytosis nor development of acute leukemia has occurred, except for progression to blast crisis in two patients with chronic myelogenous leukemia.

CONCLUSION

Combined plateletpheresis and chemotherapy is a rapidly effective initial treatment for patients with MPD with symptomatic thrombocytosis. With maintenance therapy or prompt treatment at relapse of disease, prolonged good quality survival can be expected.

Vascular complications of essential thrombocythaemia: a link to cardiovascular risk factors

Essential thrombocythaemia (ET) is a myeloproliferative disorder characterized by absolute thrombocytosis and increased incidence of thrombosis and haemorrhage. We report higher morbidity in patients with ET due to arterial ischaemic complications when cardiovascular risk factors are present. In this retrospective analysis of 46 patients, arterial complications occurred in 20/46 patients (43.4%); patients with cardiovascular risk factors, especially cigarette smoking, had more than twice as many arterial complications than patients without risk factors (62.5% v 22.7%, P < 0.05). Neither age, gender nor degree of thrombocytosis were linked to the number of complications. In contrast, we observed no association between cardiovascular risk factors and venous thrombosis or haemorrhagic complications of ET.

An abnormal pattern of multiple platelet function abnormalities and increased thromboxane generation in patients with primary thrombocytosis and thrombotic complications

Platelet aggregation (PA) induced by ADP, collagen and epinephrine, plasma levels of beta-thromboglobulin (beta TG) and thromboxane B2 (TXB2) and serum TXB2 generation were studied in 11 patients with primary thrombocytosis (7 with essential thrombocythaemia and 4 with polycythaemia vera) and compared with 16 healthy subjects. 5 patients suffered from peripheral vascular ischaemia and another 3 had venous thrombosis, but none had bleeding complications. The patients showed an abnormal pattern of platelet function and of thromboxane generation distinct from the healthy subjects in three aspects. a) Shape change was 5-26 times greater, the lag-time of collagen PA was 2.3-2.9 times longer and the extent of epinephrine PA was nil or very low. ADP- or collagen-induced PA was also reduced (p less than 0.02). b) Plasma TXB2 generation (corrected to a normal platelet concentration) stimulated by the three PA inducers was within the range of the healthy subjects in spite of the reduced extent of PA. c) Plasma beta TG level and serum TXB2 generation (both corrected to a normal platelet concentration) were 2.9-7.1 times higher (p less than 0.001) indicating enhanced in vivo platelet activation and possibly increased thrombin generation. These abnormalities were not detected in another 4 patients with secondary thrombocytosis. The abnormal pattern of platelet function and thromboxane generation can be a useful laboratory method in the evaluation of patients with primary thrombocytosis. It might also explain the thrombotic complications which occurred in 8 of the patients in a manner such that increased or normal TXB2 generation overcomes the reduced extent of PA. In this respect, the pronounced serum TXB2 synthesis might be a marker of intravascular thrombosis.

Primary thrombocythaemia: diagnosis and management

Since PT is more likely than reactive thrombocytosis to be complicated by thromboembolic manifestations, the differential diagnosis is important. A combination of positive clinical and laboratory criteria probably represents the most useful diagnostic method at present, although a molecular biological approach may prove to be of value in females in the future. Treatment to suppress the megakaryocytic proliferation is suggested in all patients, since even young patients are not immune to major complications, and treatment may possibly delay long-term myelofibrotic transition. Acute haemorrhage should be treated by platelet transfusions, with or without platelet apheresis and with rapid control of the count by hydroxyurea. Vascular occlusive lesions should be treated with aspirin, with or without platelet apheresis and with hydroxyurea. Busulphan is suggested as the drug of choice for long-term therapy in patients over 40 years of age while hydroxyurea is proposed below this age. The place of interferon-alpha therapy has not yet been established but may have a particular role in women of child-bearing age.

Primary thrombocythaemia in pregnancy

Nine pregnancies in six patients with primary thrombocythaemia are reported. Eight pregnancies resulted in the delivery of normal infants. One pregnancy ended in spontaneous abortion at 7 weeks gestation. One pregnancy was complicated by superficial thrombophlebitis and a postpartum haemorrhage. We suggest that pregnancy in patients with primary thrombocythaemia can have a favourable outcome, but requires close monitoring. Administration of aspirin during pregnancy may be of benefit.

The clinical spectrum of thrombocytosis and thrombocythemia

Platelet production is the result of a highly ordered maturation of a developmental hierarchy of megakaryocytic progenitor cells regulated by a variety of cytokines. GM-CSF, II-3 and II-6 have a stimulatory effect and several cytokines (TGF-beta, platelet released glycoprotein, platelet factor 4 and interferons) have inhibitory effects down regulating platelet production perhaps as part of an autocrine control loop. Excess platelet production can be clinically characterized as pseudothrombocytosis, thrombocytosis or thrombocythemia; the clinical features and criteria for each are defined. The term thrombocytosis infers its reactive nature and, in the absence of arterial disease or prolonged immobility, it poses little risk regardless of platelet numbers. By contrast, in thrombocythemia, whether primary or associated with other myeloproliferative lesions, significant thrombohemorrhagic events occur. The natural history, rationale, and approach to platelet reduction and control of clinical sequela are reviewed. Clinical therapeutic options include a new agent, Anagrelide.