Normal or Increased Megakaryocytes in the Marrow Megakaryocyte Thrombocytopenia

Neonatal Idiopathic Autoimmune Purpura Passive Transfer of Platelet Antibody from Mother Pregnant women with ITP are at a 50 risk for delivering thrombocytopenic infants, whether or not the mother is thrombocytopenic during pregnancy or at the time of delivery. This results from the transplacental passage of maternal IgG autoantibod-ies into the fetal circulation, with destruction of fetal platelets. Although self-limiting, neonatal ITP NITP may last for several weeks. Infants with severe...

Inherited Thrombocytopenia

Thrombocytopenia with a sex-linked pattern of inheritance has been reported in a number of families. The presence of a normal number of megakaryocytes in the bone marrow suggests that the thrombocytopenia is a result of shortened platelet survival due to an intrinsic platelet defect. The response to steroids is poor. A complete response to splenectomy has occurred in some patients. X-linked anemia with severe thrombocytopenia, due to defects in the GATA-1 gene, has been reported. Bone marrow...

Juvenile Myelomonocytic Leukemia

Blastic Bone Metastases

Incidence 1.2 per million children per year Median age at diagnosis 1.8 years 35 below 1 year of age, and only 4 above 5 years of age Male female ratio of 2 1 Association with neurofibromatosis type 1 NF-1 Children with NF-1 have more than a 200-fold increased risk of JMML. Fifteen percent of children with JMML have NF-1. Children with Noonan syndrome or trisomy 8 mosaicism are at increased risk of developing JMML. Most cases of neonates with Noonan syndrome with JMML-like presentation resolve...

Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia Osler-Weber-Rendu disease is the most common of the inherited vascular disorders. The disease is inherited as an autosomal dominant trait and bleeding occurs from vascular lesions on the skin or mucous membranes. Lesions consist of dilated arterioles and capillaries lined by a thin endothelial layer. They are typical in appearance 1-3 mm in diameter, flat, round, and red or violet in color , and they blanch on pressure. Histology of the abnormal vessels...

Polycythemia In Childhood

Polycythemia

The term polycythemia applies to an increase in circulating red cell mass to above the normal upper limits of 30 mL kg body weight excluding hemoconcentration due to dehydration . For practical purposes, this means a hemoglobin level higher than 17 g dL or a hematocrit level of 50 or more during childhood. Figure 8-1 depicts the pathogenesis of polycythemia, and Table 8-4 classifies various causes of polycythemia. Primary polycythemia results from congenital germline erythropoietin receptor...