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To investigate erythroid colony formation in polycythaemia of different types and in thrombocythaemia, a study was performed in 121 subjects, including 13 normal volunteers (N), 30 patients with Primary Proliferative Polycythaemia (PPP), 35 with Idiopathic Erythrocytosis (IE), 19 with Secondary Polycythaemia (SP), 10 with Primary Thrombocythaemia (PT) and 14 with Secondary Thrombocytosis (ST); BFU-E colony formation from peripheral blood samples was studied in the presence of medium only, medium plus a source of burst-promoting activity (BPA) and medium BPA, plus erythropoietin (Ep). In the presence of medium only, practically no colonies were seen in cultures from N and SP, while a variable number was observed in cultures from PPP, IE and PT. Significant differences between groups were as follows: N v PPP; IE v PPP; SP v PPP; N v PT; ST v PT. Such differences persisted in the presence of BPA, but disappeared when Ep was added to the cultures. Further experiments, plating non-adherent mononuclear cells in a chemically defined serum-free medium, confirmed the growth of tiny erythropoietic colonies from circulating stem cells of patients with PPP and PT, in the absence of BPA and EP. These results provide a useful criterion to differentiate PPP, as a group, from other types of polycythaemia; individual cases of IE may need further characterization.

Two patients with coexistent hereditary haemorrhagic telangiectasia (HHT) and primary thrombocythaemia (PT) are presented. In one of them, both diseases were detected at the same time. In the other, signs of HHT were present 20 years prior to the diagnosis of PT. Both patients had recurrent gastrointestinal haemorrhage with consequent anaemia, and multiple gastric telangiectases were demonstrated endoscopically. Persistent and severe haemorrhage from gastric telangiectases in one of the patients was successfully controlled by endoscopic monopolar electrocoagulation. The very high platelet counts were reduced with melphalan in one patient and with busulfan in the other. The degree of severity of both disorders was parallel in both cases. We suggest that the coexistence of these two rare disorders in one and the same patient may represent a syndrome that could be more common than hitherto known.

Primary thrombocythaemia (PT) is the most frequent among the rare chronic myeloproliferative disorders. Life expectancy is determined by thromboembolic and haemorrhagic complications, which can be prevented by cytoreductive therapy. For a long time, hydroxyurea has been considered as the therapeutic gold standard. However, hydroxyurea treatment is not lineage-specific, may not be tolerated because of adverse effects (skin, gastrointestinal tract) and is leukaemogenic when sequentially used with other DNA-targeting drugs. Hence, anagrelide was welcomed in 1988 when it was first described as being efficient at normalising elevated platelet counts, specific for megakaryocytes and non-mutagenic. Since then, anagrelide has been approved in the US and Canada (Agrylin), Shire Pharmaceuticals) as well as in Austria and other countries of the EU (Thromboreductin), AOP Orphan Pharmaceuticals). Clinical Phase III trials (PT1 and ANAHYDRET) are underway to directly compare the efficacy and safety of anagrelide and hydroxyurea.

A young primigravida presented with postpartum haemorrhage with no apparent cause following a low forceps delivery. She was extremely pale with gross hepato-splenomegaly. Hysterectomy was performed following three episodes of disseminated intravascular coagulation. Investigations revealed an extremely high platelet count with poor aggregatory function. A diagnosis of primary thrombocythaemia was made.

A morphometric evaluation of number and grouping of megakaryocytes (MK) in five different groups of chronic myeloproliferative disorders (CMPD) was performed by counting 60 high power fields equaling approximately 14.28 mm2 of haematopoiesis in each case. Twenty-one up to 29 cases were evaluated for each of five categories of CMPD and one control group; a total of 132 cases of CMPD and 33 control cases were used. The mean number of MK per square millimetre was 15.54 +/- 1.53 in chronic myeloid leukaemia of common or granulocytic type (CML.CT), 69.91 +/- 5.85 in CML with megakaryocytic increase (CML.MI), 59.59 +/- 3.27 in polycythaemia vera (P. vera), 59.85 +/- 4.59 in primary thrombocythaemia (PTH), 67.58 +/- 4.11 in chronic megakaryocytic granulocytic myelosis (CMGM), and 19.7 +/- 3.07 in controls. The distinction between free or isolated MK, and between clustered or grouped MK corresponds to the total cell counts of MK in the various groups of CMPD. Clustering of MK was significantly higher in CMGM and PTH compared to other groups, but the difference between them was not statistically significant. Significant differences in the mean number of MK were obtained between controls and CML.CT on the one hand and all other groups of CMPD on the other. The results further support the histological sub-classification of CMPD according to the primary disorders of the Hannover classification (not advanced by sclerosis, fibrosis or excess of blasts, respectively).

Mastocytosis is an uncommon disease characterized by a proliferation of tissue mast cells involving various organs, particularly the bone marrow. Though rare, the association of mastocytosis and haematological malignancies is well established. However, the frequency of mastocytosis reported in patients with essential thrombocythaemia is relatively low. We report five cases of such an association. Our five patients were undergoing evaluation for thrombocyte when the bone marrow biopsy revealed the presence of mastocytosis. The pathogenetic significance of this association is poorly understood. The different hypotheses are discussed.

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.

Clinical uses for recombinant human erythropoietin (rHuEPO) therapy continue to expand. Initial use was in anaemia associated with end-stage renal disease, but more recently there have been many reports of the benefits of erythropoietin in other clinical situations such as cancer-related anaemia. Recombinant erythropoietin reduces the need for blood transfusion and hence exposure to donor blood products as well as improving quality of life. We report four patients who were transfusion dependent, none of whom had licensed indications for the use of recombinant erythropoietin. Two patients had microangiopathic haemolytic anaemia secondary to mechanical valve haemolysis and were unsuitable for any further cardiac intervention. One patient had anaemia of chronic disease and anti-Vel red cell antibodies, making compatible blood transfusions difficult to obtain. The fourth patient had primary thrombocythaemia and developed transfusion-dependent anaemia secondary to myelosuppressive agents. All four patients had a relative deficiency in endogenous erythropoietin levels ranging between 7 and 41 IU/l. After commencing recombinant erythropoietin therapy, all had a response in haemoglobin of at least 1 g/dl with an overall improvement in their quality of life. We conclude that rHuEPO is a very convenient and useful form of treatment in transfusion-dependent anaemia and in some cases beyond the licensed indications. The Hematology Journal (2004) 5, 181–185. doi:10.1038/sj.thj.6200350

A case of non-fatal massive bone marrow necrosis (MBMN) is reported in a patient with primary thrombocythaemia five years after diagnosis. No precipitating cause was identified. The patient developed postnecrotic myelofibrosis six months later. As far as is known, this is the first report of MBMN in a case of primary thrombocythaemia.

Essentially, the chronic myeloproliferative diseases comprise the four following diseases: (1) chronic myeloid leukemia, and (2) osteomyelofibrosis (osteomyelosklerosis), (3) primary thrombocythaemia, (4) polycythaemia vera.

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.

A 28 year old patient with primary thrombocythaemia, who had had two stillbirths in the third trimester, is reported. She was successfully treated with hydroxyurea and delivered a healthy 6lb boy by elective caesarean section. The ease with which this treatment can be given, its high level of tolerance among patients, and its low cost are likely to increase its use as a safe and effective treatment in pregnant patients with primary thrombocythaemia.

Summary. Routine blood examination of a 27-year-old female revealed a platelet count of 2000 109/1. Bone marrow cells showed the Philadelphia chromosome which was one product of a complex rearrangement of chromosomes 9, 22 and X. Her platelet count was lowered by plateletphoresis and chemotherapy. She remains in good health 19 months later, but her thrombocythaemia is considered to be an early manifestation of chronic myeloid leukaemia.

The formation of erythropoietic colonies from the peripheral blood of normal subjects, patients with primary proliferative polycythaemia (PPP) and primary thrombocythaemia (PT) was studied, using a chemically defined serum-free (S-) medium. Colony formation was markedly more prominent in the presence of burst-promoting activity (BPA) and erythropoietin (Ep) than with medium alone (P less than 0.001). In cultures using medium alone, significantly more PPP patients formed colonies than the control group (P less than 0.05). In the PT group this difference did not achieve statistical significance, but the mean BFU-E yield was significantly greater than in controls (P less than 0.05). In a separate series of experiments, parallel cultures in serum-containing (S+) and serum-free (S-) systems, in the presence of BPA and Ep did not show any significant difference in colony yield. The growth of 'endogenous' colonies in cultures with serum-free medium alone could be due to a peculiar sensitivity of erythropoietic progenitors to growth factors other than Ep.

Summary. Thirty-seven patients with primary thrombocythaemia (PT) treated with busulphan have been followed for periods up to 25 years. Reduction of the platelet count to less than 400 × 109/l resolved vascular occlusive symptoms, but haemorrhagic symptoms often remained unaltered. Cox regression analysis indicated that there were only two prognostically important presenting features; age had a strong inverse correlation with survival and vascular occlusive symptoms correlated with a better survival. Median duration ofsurvival on treatment was 9·8 years. The number of deaths was 2·1 times that of a comparable control group, with deaths from myelofibrosis markedly increased. Deaths from thrombosis and malignant diseases, including leukaemia, were not significantly different from the number expected. which emphasizes the efficacy and the relative safety of busulphan for the long-term treatment of PT. Progression of PT into myelofibrosis occurred in 24% of cases and 9% became polycythaemic. Two additional cases of ‘thrombocythaemia'with a Philadelphia chromosome (and no overt evidence of chronic granulocytic leukaemia) are also presented.

Cytogenetic analysis was performed on bone marrow cells in 14 untreated patients with primary thrombocythaemia. The chromosome studies mainly concerned the G-group, i.e. chromosomes Nos. 21 and 22. Three different staining methods were used: Giemsa without banding, Q-banding and R-banding. No detectable changes were observed in any of the chromosomes belonging to the G-group. In 2 of the patients chromosome abnormalities were found (14 %). In one of them the first examination showed a normal karyotype. The abnormal clone developed several years later, although no myelosuppressive therapy was given. The frequency of abnormal clones in untreated primary thrombocythaemia is similar to that found in polycythaemia vera (14 %).

Megakaryocyte morphology was studied quantitatively in primary thrombocythaemia (PT) and in chronic myelogenous leukaemia (CML). The relation of thrombokinetics to megakaryocyte quantifications was evaluated in PT and compared to previously obtained results in polycythaemia Vera (PV) and idiopathic thrombocytopenic purpura (ITP). Megakaryocyte area, number and volume per μl bone marrow were significantly higher in PT as compared to controls. The nuclear lobe number was significantly increased and the megakaryocytes were shifted towards more mature forms, suggesting a prolonged megakaryocyte generation time. In CML the megakaryocyte number and volume per μl bone marrow were also significantly above normal, but the megakaryocyte area, number of lobes and degree of megakaryocytic maturation were significantly below normal. Platelet production was in PT 6.2 times normal and proportional to the increase in megakaryocyte volume which was 6.8 times normal. In PV with major splenomegaly the mean platelet production rate was higher (9.5 times normal) although their peripheral platelet count was lower than in PT. This discrepancy is explained by the greatly enlarged splenic platelet pool in the PV patients. In ITP the mean platelet production rate was 2.2 to 3 times normal and was significantly lower than in PT and PV.

Summary In a group of 14 patients with primary thrombocythaemia (PT) the study of erythropoietic colony formation in vitro showed the development of so-called ‘endogenous’colonies, namely colonies with no added erythropoietin (Ep), in all but one case. In the presence of added Ep the colony formation increased slightly in the PT group, but the rise in the control group was so pronounced that any statistical difference between the two groups disappeared. No ‘endogenous’colonies were observed in cases of secondary thrombocytosis. This finding reinforces the view that PT is a myeloproliferative disorder and establishes that some erythroid progenitors show the same high sensitivity to Ep as that found in polycythaemia vera; it is of interest that, in the patients studied, there was no apparent involvement of erythropoiesis.

Primary thrombocythaemia is described in a 6-year-old boy and the literature is reviewed. The features distinguishing primary thrombocythaemia from secondary thrombocytosis are discussed, and the value of platelet function tests and platelet biochemistry are emphasized.

SummaryA 20-year-old male who required splenectomy following abdominal trauma was subsequently shown to have primary thrombocythaemia. This report illustrates the diagnostic problems associated with a refractory post-splenectomy thrombocytosis, and the therapeutic difficulties in the management of primary thrombocythaemia are discussed.

SUMMARY The use of “‘Iridium oxine as a platelet label for the performance of platelet life-span studies has been examined. Platelet life-span in normal subjects varied between 8-10 and 10-36 d. Patients with primary thrombocythaemia had clearly reduced platelet life-span whether or not they presented with vascular occlusion and this abnormality persisted after reduction of the platelet count to normal by busulphan therapy. Patients with similarly elevate platelet counts due to chronic granulocytic leukaemia or after splenectomy had platelet life-span values in the normal range. Plasma β-TG levels could not be used to predict platelet life-span in these groups of patients. Measurement of platelet life-span using 111 Indium labelled platelets is a useful technique in the examination of platelet function in occlusive vascular disease.

Splenic volume was measured by visual assessment of planar images of the spleen, and also by single photon emission computerised tomography (SPECT) using 99mtechnetium tin colloid, in a group of 33 patients with primary thrombocythaemia (PT) or reactive thrombocytosis. Volumes greater than 337 cm3 correlated strongly though not absolutely with PT, all patients with volumes greater than this figure being in the PT group. Simple visual assessment of planar images by an experienced observer matched measured splenic volumes very closely.

Forty new patients with elevated platelet counts (greater than 600 x 10(9)/l) and without palpable splenomegaly were assigned to diagnostic groups defined by essentially conventional criteria after 3 months follow up: Proliferative (17), reactive (17) or unclassified (six). Mean platelet volume (MPV), platelet distribution width (PDW), platelet nucleotide ratio (ATP:ADP), unstimulated BFU-E derived colony formation from peripheral blood, spleen scan and clinical ischaemia were assessed at the outset, with a view to defining diagnostic criteria for distinguishing primary thrombocythaemia from reactive thrombocytosis. All except the first variable were significantly associated with diagnostic group (P less than 0.05). A simple scoring system was devised: enlarged spleen on scan, or presence of BFU-E, each scored 2; elevated PDW (greater than 2 SD from mean), elevated ATP:ADP (greater than 4 SD from mean) or presence of clinical ischaemia, each scored 1. Score totals greater than or equal to 3 predicted primary thrombocythaemia, and totals less than 3 suggested reactive thrombocytosis (predictive value 89%). The system correctly predicted diagnosis in four out of four (probably six out of six) patients whose diagnosis was not apparent initially, and thus whose results were not used in constructing the scoring system. Exclusion of BFU-E from the system resulted in only one incorrect prediction in this group.