Pediatric heparin-induced thrombocytopenia: management with Danaparoid (orgaran).

Heparin-induced thrombocytopenia is a rare and serious complication of anticoagulation therapy. There remains a paucity of information pertaining to alternative anticoagulation strategies for use during cardiopulmonary bypass concomitant with heparin-induced thrombocytopenia, especially in children. We report the successful treatment of heparin-induced thrombocytopenia and subsequent hemorrhagic complications postoperatively in a 2-year-old child with Danaparoid (orgaran). Emergent conduit revision with cardiopulmonary bypass was required for a thrombosed systemic-venous to pulmonary-arterial connection (completion modified Fontan procedure). Required doses of Danaparoid were consistently twofold that previously reported for adults.

Reticulated platelet counts in the assessment of thrombocytopenic disorders.

Reticulated platelets (RP) are the youngest platelets in the circulation and can be measured by analysing the RNA content of platelets from whole blood or platelet-rich plasma by flow cytometry. Increased RP are indicative of increased production of platelets. Despite the current lack of standardization for the measurement of RP, it is useful in the assessment of patients with ITP by aiding the distinction of these patients from those with decreased platelet production. RP counts also have a role in the assessment of the complicated patient with multiple possible aetiologies for thrombocytopenia. Measurement of the RP count may hold predictive value for marrow recovery following myelosuppressive or myeloablative chemotherapy, and may play a role in monitoring the administration of the various thrombopoietins currently under clinical trial.

Regression of extramedullary haemopoiesis and augmentation of fetal haemoglobin concentration during hydroxyurea therapy in beta thalassaemia.

Hydroxyurea increases fetal haemoglobin in many patients with sickle cell anaemia, but its effectiveness in thalassaemia appears to be less consistent. We describe the response to hydroxyurea in an adult male with homozygous beta thalassaemia, symptomatic paraspinal extramedullary haemopoiesis, bone pain, and progressive tissue iron loading. Prior to therapy with hydroxyurea the circulating haemoglobin (Hb) concentration was 7.0 g/dl and absolute fetal haemoglobin concentration was 5.0 g/dl. Administration of sodium phenylbutyrate had induced no increase in either parameter. Subsequent therapy with hydroxyurea was associated with increases in total haemoglobin to 9.0 g/dl, and in fetal haemoglobin to 7.6 g/dl. Ineffective erythropoiesis was reduced and extramedullary haemopoiesis regressed during therapy.

Reticulated platelet counts in the diagnosis of acute immune thrombocytopenic purpura.

PURPOSE: Bone marrow aspiration is often performed to diagnose childhood acute immune thrombocytopenic purpura (ITP) because no non-invasive investigation to confirm the diagnosis is routinely available. Reticulated platelets (RPs--young platelets characterized by a high RNA content--increase with increased platelet production and may be useful in the diagnosis of ITP. METHODS: To assess the role of RP counts in distinguishing ITP, we compared counts from 15 consecutive patients with ITP with counts from 20 patients with acute lymphoblastic leukemia (ALL), 10 with aplasia, and 27 healthy normal children. Whole blood in edetic acid (EDTA) was labelled with a platelet-specific monoclonal antibody and incubated with thiazole orange (TO). A standard gate was set to achieve a fluorescence value of 1.3 +/- 0.5% for control lyophilized platelets. RESULTS: Patients with ITP had a mean (+/- 1 standard deviation) RP level of 32.9 +/- 10.2%; patients with ALL, 6.6 +/- 3.1%; patients with aplasia, 3.4 +/- 2.0%; and normal patients, 7.9 +/- 2.9%. The difference in RPs between the ITP group and the ALL, aplasia, and normal groups was highly significant (p < 0.0001 each), with no significant difference between the non-ITP groups (p = 0.12). CONCLUSIONS: Measuring RPs by this simple whole-blood cytometric technique discriminated very well between the acute ITP and non-ITP groups. This test has a strong positive predictive value and may prove very useful in the assessment of childhood acute ITP and the screening of candidates for bone marrow aspiration.

Cellular expression of adhesion factors in childhood rhabdomyosarcoma.

Tumor invasion and metastasis are believed to involve the adhesive interaction of tumor cells with extracellular matrix (ECM). This study reports the expression of laminin, fibronectin, thrombospondin, tenascin, and CD44 in rhabdomyosarcoma cells taken from tumors derived from 12 pediatric patients. Twelve paraffin-embedded rhabdomyosarcomas consisting of five alveolar, six embryonal, and one botryoid subtype were examined. All tumors demonstrated positive staining for tenascin and thrombospondin, 10 were positive for fibronectin, 5 positive for laminin, and 4 positive for CD44. Both specimens without cellular staining for fibronectin were of embryonal subtype and no alveolar rhabdomyosarcomas were positive for CD44. No association of the expression of the studied ECM proteins and receptor with the presence of metastatic disease at clinical presentation or with the level of tumor differentiation was found.