case_images: PMC10867169_01
case_images: (A) Peripheral blood film showing increased platelets with clusters and giant platelets, morphologically normal white blood cells and erythrocytes. May-Giemsa, x63 objective. (B) Bone marrow trephine showing megakaryocytic clustering with atypical megakaryocytes. H&E, x20 objective.
case_images: fonc-14-1326209-g001.jpg
case_images: PMC10867169_01_fonc-14-1326209-g001.jpg
case_images: f1
case_images: Complete blood count showed normal hemoglobin (Hb) and white blood cell count, but platelet count was markedly elevated at 1,292x109/L ( Figure 1A ). It showed hypercellular bone marrow with clusters of abnormal megakaryocytes ( Figure 1B ).
case_images: (A) Platelet count (x109/L), PTT (seconds), Hemoglobin (g/L), vWF antigen (U/mL), vWF activity (U/mL) and coagulation factor VIII activity (U/mL) for patient #1 4 hours and 42 hours after bone marrow biopsy. Decrease platelet count after HU administration was accompanied by the normalization of coagulation parameters and von Willebrand panel. (B) Platelet count (x109/L), PTT (seconds), Hemoglobin (g/L), vWF antigen (U/mL), vWF activity (U/mL) and coagulation factor VIII activity (U/mL). Decrease platelet count after HU administration was accompanied by the normalization of coagulation parameters and von Willebrand panel.
case_images: fonc-14-1326209-g002.jpg
case_images: PMC10867169_01_fonc-14-1326209-g002.jpg
case_images: f2
case_images: As shown in  Figure 2  the patient had extreme thrombocytosis (platelet count rose to 1,491x109/L), elevated PTT (43 sec), normal INR and Hb 145 g/L. Repeated blood work showed normalization of PTT (34 sec) and vWF profile ( Figure 2 ).