[Clinical characterization of essential thrombocythemia in comparison with other myeloproliferative diseases and reactive thrombocytoses]

Histologic findings in bone marrow biopsies of patients with thrombocythemic cell counts

Histologic diagnoses from bone marrow biopsies were analyzed in a total of 1165 patients presenting with thrombocythemic platelet counts at initial examination. Two cut-off points suggested by the Polycythemia Vera Study Group to define thrombocythemia by platelet counts were compared: the former limiting value of 1000 x 10(9)/l platelets versus the recently proposed value of 600 x 10(9)/l. The percentage of all nonproliferative disorders was 41% under the lower, dropping to 11% under the high cut-off point. The respective figures for myeloproliferative disorders increased from 49% under the lower to 74% under the high limiting value. Primary thrombocythemia was included in 72% by the lower, and in only 40% by the high limiting value when classified by its histologic pattern in bone marrow biopsy. A striking decrease of platelet counts occurs, related to fiber increase, among each of three main groups of myeloproliferative disorders: in CML with megakaryocytic predominance from 40% down to 25%, in megakaryocytic-granulocytic myelosis (primary, i.e., agnogenic myelofibrosis) from 36.6% to 10%, and in primary thrombocythemia from 72.6% to 28.6% in cases with reticulin sclerosis.

Cutaneous manifestations in patients with essential thrombocythemia

In a retrospective study of 268 patients with essential thrombocythemia, related cutaneous manifestations were found in 58 (22%). In 27 cases (10%) the related skin lesions were present at the time of the primary diagnosis of essential thrombocythemia. Hematomas, ecchymoses, petechiae, or purpura occurred in 24 (41%) of the 58 patients. Fifteen patients (26%) had erythromelalgia, in 11 of whom it was the initial complaint. Livedo reticularis, recurrent superficial thrombophlebitis, ischemic complications with gangrene, leg ulcers, or ulcers on the toes were other manifestations. Urticaria occurred in two patients, and Raynaud's phenomenon and necrotizing vasculitis were each observed in one patient. Platelet function may be abnormal, and this was found in 13 of 19 patients studied, 9 of whom had spontaneous platelet aggregation. Knowledge of the cutaneous manifestations in essential thrombocythemia may lead to its earlier detection. Prompt diagnosis of essential thrombocythemia is important because treatment may prevent severe hemorrhagic or thrombotic events.

[Megakaryocytic myelosis--clinical aspects, morphology and platelet function]

The study reviews 22 patients, aged between 19 to 73 years, with megakaryocytic myelosis. In the course of the disease 11 patients presented haemorrhagic manifestations, 12 patients thrombotic complications, and 6 patients the association of haemorrhage and thrombosis. The maximum platelet counts ranged from 524 to 2700 x 10(9)/l. The bone marrow showed a conspicuous megakaryocytic proliferation with polyploidy of the nuclei, giant forms and clusters. Marked alterations of erythro- and granulopoiesis were excluded. There was no evidence for a reactive thrombocytosis in any case. Patients with thrombocythaemia due to megakaryocytic myelosis (n = 14), with secondary thrombocytosis of various origin (n = 16), and a control group of healthy donors (n = 20) were investigated with respect to the aggregation behaviour and the total calcium content of blood platelets. In 9 of 14 patients with megakaryocytic myelosis platelet rich plasma did not respond to epinephrine (15 mumol/l), a concentration which induced at least weak aggregation in 14 of 16 patients with secondary thrombocytosis and also in healthy subjects. In patients with megakaryocytic myelosis the mean extent of aggregation induced by epinephrine, collagen or adenosine diphosphate was significant lower as compared to controls whereas in patients with secondary thrombocytosis in most cases this parameter did not differ significantly from that of controls. The total calcium content of platelets was significantly lower in both groups of patients as compared to controls. In 14 patients with megakaryocytic myelosis the concentration of the glycoprotein (GP) IIb-IIIa complex was estimated by crossed- and rocket-immunoelectrophoresis and found to be decreased in 8 of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Essential thrombocythemia. Clinical characteristics and course of 61 cases

Sixty-one patients with essential thrombocythemia (ET) were followed from 1974 through 1987 at the Medizinische Poliklinik. Fifty-one patients (84%) presented with thromboembolic complications, and eight patients (13%) with hemorrhages. In seven patients (12%), a thrombocytosis was detected accidentally. Disturbances of the microcirculation (67%), mainly of the fingers and toes (53%), were the most frequent thromboembolic symptoms. The mean age of all patients was 58 years (male patients, 61 years; female patients, 56 years). The average platelet count at diagnosis was 897,000/microliter. The average maximal platelet count was 1.231 X 10(6)/microliter (range, 500,000/microliter to 4 X 10(6)/microliter). Seventy-two percent had a moderate leukocytosis (average, 12,400/microliter), 34% a splenomegaly, 29% a hepatomegaly. Signs of hypermetabolism were infrequent, lactate dehydrogenase (LDH) and uric acid elevations, if present, were moderate. Bleeding time and viscosity were normal in most patients. Spontaneous platelet aggregation was increased in 81% of patients (n = 40). Platelet aggregation studies with the aggregation inducing substances adenosine diphosphonate (ADP), platelet activating factor (PAF), thrombin, collagen, and adrenalin showed hypoaggregation in most patients. Adrenalin-induced aggregation distinguished best between ET-patients and reactive thrombocytosis showing hypoaggregation in all ET-patients tested (n = 16) and in none of 22 controls. Bone marrow studies were performed in 57 patients. The histologic studies (done in 49 patients) were consistent with a chronic myeloproliferative disorder in all cases. In 41 cases (84%) the picture of a megakaryocytic myelosis was found, in 12 of these a granulocyte-rich form of megakaryocytic myelosis. Cytologic studies only (eight patients) did not differentiate ET well from reactive thrombocytosis. Platelet aggregation studies and bone marrow histology may be of help in the diagnosis of difficult cases of thrombocytosis. The Philadelphia status was negative in all cases studied (14 patients). Fourteen patients died. The causes of death were thromboembolic complications in probably 11 and acute leukemia in two patients. The probability of 10-year survival is 64% after a mean follow-up time of approximately 5 years. It appears that considering the average age of ET patients at diagnosis, life expectancy is close to normal.

[Thrombocyte function in essential thrombocythemia and reactive thrombocytosis]

Blood of 16 patients with essential thrombocythemia (ET), 9 patients with reactive thrombocytosis (RT) and 13 healthy persons was used for platelet aggregation studies. When the aggregation was induced with adenosine diphosphate (0.01 microM), collagen (0.1 micrograms/ml) or platelet activating factor (PAF 0.5 microM) the plasma of the patients with ET showed significantly decreased aggregation (35%-44% of the value for the control groups). Independent of inhibitors of platelet aggregation, thrombin (0.05 U/ml) caused similar aggregation in healthy controls and patients with ET; patients with RT showed an increase aggregation. Adrenalin-induced aggregation discriminated best between patients with ET and controls. Adrenalin in concentrations ranging from 0.01 micrograms/ml to 100 micrograms/ml caused comparable dose-related amounts of aggregation in healthy controls and patients with RT. Over the whole concentration range, patients with ET showed significantly decreased aggregation (28%-34% of the value for the control groups). This difference proved to be independent of the influence of inhibitors of platelet aggregation. Though concentrations of alpha1-acid glycoprotein never reached inhibitory levels in the plasma of patients with ET (n = 12) they were significantly higher compared with those in normal plasma (n = 12). Fibrinogen concentrations in plasma of ET-patients (n = 12) were in the normal range. Cellular adenosine 3'-5'-cyclic monophosphate concentrations in ET (n = 10) are comparable with normal values (n = 5). The significance of the results for diagnosis and better pathophysiological understanding of ET is discussed.