Ann Hematol (1994) 69:81-84 Springer-Verlag 1994 P. J. J. van Genderen J. J. Michiels S. C. P. A. M. van der Poel-van de Luytgaarde H. H. D. M. van Vliet Acquired von Willebrand disease as a cause of recurrent mucocutaneous bleeding in primary thrombocythemia: relationship with platelet count Received 2 March 1994 / Accepted 20 May 1994 Summary We present a 4-year follow-up of a 42-year- von Willebrand factor deficiency. An inverse relation- old patient with primary thrombocythemia whose clini- ship between platelet number and plasma high-molecu- cal course was complicated by two major mucocuta- lar-weight multimers of von Willebrand factor was de- neous bleeding episodes. On both occasions an ac- monstrated. quired functional yon Willebrand factor deficiency was demonstrated. In contrast to what is reported in the lit- erature, an inverse relationship between platelet num- Case report ber and plasma high-molecular-weight multimers of von Willebrand factor was established. A 42-year-old woman was referred to our department in Decem- ber 1989 with upper abdominal complaints due to massive sple- Key words Primary thrombocythemia nomegaly. Ultrasound examination of the abdomen revealed an Myeloproliferative disorder . von Willebrand factor enlarged spleen of 20 cm and thrombosis of the splenic vein. Sub- Acquired von Willebrand disease Platelets sequent endoscopy showed esophageal varices. A slight thrombo- cytosis of 431 x 109 platelets per liter was established (Fig. 1). He- Bleeding moglobin levels, white cell count and differentiation, creatinine, urea, and liver function tests were all normal. Extended hemos- tatic analysis excluded the presence of a lupus anticoagulant anti- Introduction body and a deficiency of antithrombin III, protein C, and protein S. Bone marrow smear and biopsy material showed an increased cellularity of normal hematopoiesis, a pronounced increase of Primary thrombocythemia (PT), a clonal myeloprolifer- clustered megakaryocytes, and the presence of fine reticulin fi- ative disorder characterized by a persistent elevation of bers, but the absence of collagen fibers and osteosclerosis, compa- the platelet count, paradoxically predisposes to both tible with the diagnosis of PT [15]. The score for the leukocyte alkaline phosphatase stain was 129 (normal 20-100 U/ml). Splen- thrombosis and hemorrhages [13, 15]. Despite the iden- ectomy in December 1989 (spleen weight 788 g) was uneventful. tification of a broad array of specific structural, bio- In March 1990, the platelet count rose to about 3500 x 109/1; this chemical, and metabolic platelet defects in patients was associated with spontaneous mucocutaneous bleeding con- with PT, a convincing correlation between these defects sisting of easy bruising, recurrent ecchymoses after minor injuries, and the clinical complications of thrombosis and bleed- and melena, causing a fall of the hemoglobin level from 7.3 to 4.6 mmol/1. Extended coagulation tests revealed a functional defi- ing has never been established [13, 15]. ciency of plasma von Willebrand factor [yon Willebrand factor Several authors have described a decrease or ab- antigen (vWF:Ag) 1.36U/ml; ristocetin co-factor activity sence of plasma high-molecular-weight multimers of (vWF: RCoF) 0.40 U/ml, and collagen binding activity yon Willebrand factor (vWF) in patients with myelo- (vWF:CBA) 0.22 U/ml, normal values for all vWF-related activi- ties 0.60-1.40 U/ml)] and a prolonged Ivy bleeding time (> 15 proliferative disorders and associated bleeding tenden- rain; normal _< 4 min). Platelet aggregation tests were normal. cy [4, 5, 10]. We present here a 4-year follow-up of a From that time on we prospectively studied plasma von Wille- patient with PT whose clinical course was complicated brand factor activities in relation to the platelet count. Reduction by two bleeding episodes associated with an acquired of the platelet count with hydroxyurea resulted in disappearance of the bleeding symptoms and the functional yon Willebrand fac- tor defect and in a normalization of the Ivy bleeding time. At platelet counts between 700 and 1650 x 109/1 for more than 1 year P. J. J. van Genderen (N~I) J. J. Michiels neither the bleeding nor the functional von Willebrand factor de- S. C. P. A. M. van tier Poel-van de Luytgaarde fect (vWF:Ag varied from 1.22 to 2.00 U/ml; vWF:RCoF from H. H. D. M. van Vliet 0.64 to 1.72 U/ml, and vWF: CBA from 0.67 to 1.26 U/ml) recur- Department of Hematology, University Hospital Dijkzigt, red. Erasmus University, Dr. Molewater plein 40, Discontinuation of hydroxyurea because of side effects (head- NL-3015 GD Rotterdam, The Netherlands ache and nausea) in August 1992 resulted in a rapid increase in 82 Platelet count I (x 109/1) 4000 Splen~ctomy / 1989/1990 2.0 Ratio 3000 1.5 2000 /i i i",',,,, /",, ,' ., 1.0 '/":i" v''':'''I /'x V" .,'" 1000 0.5 I I I I I I 1 I I I 0 0 nov I dec I jan feb I mar I aprilI may I juneI july I may june july aug sept oct nov dec jan platelets ............ vWF:RCoF/vWF:Ag .......... vWF:CBA/vWF:Ag mucocutaneous bleedings Fig. 1 The clinical course of a patient with primary thrombocy- wells were incubated with 1/200 dilution in PBS-Tween-albumin themia was complicated by two mucocutaneous bleeding episodes of horseradish peroxidase-conjugated rabbit polyclonal immuno- at platelet counts above 2000 x 109/1. On both occasions a func- globulins to human vWF (Dakopatts, Denmark) for another 2 h tional von Willebrand factor deficiency was demonstrated; this at room temperature. After washing, 100 Ixl ABTS substrate solu- disappeared after reduction of the platelet count with hydroxyur- tion was added. After 15 min incubation the color development ea. Von Willebrand factor activities are expressed as the ratio of was stopped by the addition of 10 ixl concentrated acetic acid and either vWF: RCoF/vWF: Ag or vWF: CBA/vWF: Ag to denote the extinction was measured at 414 nm. The multimeric pattern of the amount of functionally active von Willebrand factor. The up- vWF was visualized according to Brosstad et al. [2]. per two horizontal lines represent the normal range for the The relationship between platelet count and plasma levels of vWF: RCoF/vWF: Ag and vWF: CBA/vWF: Ag ratios. The lower von Willebrand factor was analyzed by linear regression and two horizontal lines indicate the normal range for the platelet Spearman's rank correlation test. Statistical significance was ac- count cepted at p < 0.05. circulating platelets (platelet counts 3700-4000 x 109/1) and recur- Results rence of the mucocutaneous bleeding tendency, which was char- acterized by easy bruising, prolonged bleeding after minor cuts, The clinical course of the described patient was compli- and menorrhagia, causing a fall of the hemoglobin level from 7.0 cated by two major bleeding events. On both occasions to 3.7 mmol/1. Again, a functional von Willebrand factor defect (vWF:Ag 1.31 U/ml; vWF:RCoF 0.46 U/ml, and vWF: CBA 0.11 an acquired von Willebrand defect and a prolonged Ivy U/ml) and a prolongation of the bleeding time (> 15 min) were bleeding time were demonstrated, occurring at platelet demonstrated. The bleeding symptoms and the functional von counts above 2000 x 109/1 (Fig. 1). At times of manifest Willebrand factor defect disappeared after reduction of the plate- bleeding, the vWF: RCoF/vWF: Ag ratios and let count with hydroxyurea. The hemoglobin level completely re- covered with oral iron administration. vWF: CBA/vWF: Ag ratios were decreased at 0.40+0.13 and 0.19_+0.08, respectively, indicating a functional deficiency of vWF. Reduction of the platelet Material and methods count with hydroxyurea resulted in disappearance of the bleeding symptoms as well as of the acquired func- All hemostatic tests were performed using routine procedures. tional von Willebrand defect (Fig. 1) and in a normali- Platelets were counted electronically in blood anticoagulated with zation of the Ivy bleeding time. A significant inverse EDTA. Bleeding times were measured according to Ivy et al. [9]. relationship between the platelet count and the ratios Von Willebrand factor antigen was assayed by an ELISA using rabbit anti-human vWF and rabbit horseradish peroxidase-conju- of vWF:RCoF/vWF:Ag (r=-0.728, p<0.001) and gated anti-human vWF polyclonal antibodies [7]. Ristocetin co- vWF:CBA/vWF:Ag (r=-0.834, p<0.001) was de- factor activity was assayed with formalin-fixed platelets [11] (in- monstrated (Fig. 2). Analysis of the vWF multimers at tra-assay variation 10%; inter-assay variation 11%). The binding different levels of thrombocytosis (Fig. 3) revealed a of vWF to collagen was measured according to the ELISA-based progressive decrease of the high-molecular-weight mul- method of Brown and Bosak [3], with slight modifications (intra- assay variation 5%, inter-assay variation 9%). Microtiter plate timers of vWF with increasing platelet counts. wells (A/S Nunc, Roskilde, Denmark) were coated overnight at 4~ with 100 ~1 of a 0.2-mg/ml suspension of collagen (bovine achilles tendon, type I, Sigma, St. Louis, USA) in 20 mM acetic acid. After washing with PBS-Tween, 100 txl of a 1/40 dilution of the test plasmas in PBS-Tween-albumin were added to the wells and incubated for 2 h at room temperature. After rinsing, the 83 1.50 strated, resulting in a functional von Willebrand factor defect at platelet counts above 1000x109/1. With in- 0 creasing platelet counts both the vWF:RCoF/vWF:Ag o o 0 and vWF: CBA/vWF:Ag ratios progressively de- 1.00 "'""" .. creased, suggesting a deficiency of the high-molecular- im0 4~ O'.~,.