Introduction When a patient with a suspected vascular anomaly is referred for consultation, it is critical to establish the correct diagnosis. The classification of vascular anomalies from the International Society for the Study of Vascular Anomalies (ISSVA) updated in 2018…
Hemostatic disorders Physiology of hemostasis As a result of injury to the blood vessel endothelium, three events take place concurrently: 1. vasoconstriction (vascular phase), 2. platelet plug formation (primary hemostatic mechanism—platelet phase), and 3. fibrin thrombus formation (initiation, amplification, and…
Platelets are an important component in primary hemostasis. Defects in platelet number or function may lead to bleeding and bruising. Bleeding due to platelet disorders usually involves skin and mucous membranes, presenting as petechiae, purpura, ecchymosis, epistaxis, hematuria, menorrhagia, as…
The most inclusive term for white blood cells (WBCs), that is, leukocytes, refers to the colorless amoeboid blood cells of the immune system involved in counteracting foreign substances and disease. Among these cells are granulocytes, a term that most accurately…
The term “polycythemia,” particularly as it pertains to newborns and children, should be more accurately termed erythrocytosis because it generally refers to conditions in which only erythrocytes are increased in number. It is usually a response to tissue hypoxia from…
Sickle cell disease Pathophysiology HbS arises as a result of a point mutation (A→T) in the sixth codon of the β-globin gene on chromosome 11, which causes a single amino acid substitution (glutamic acid to valine at position 6 of…
The causes of extracorpuscular hemolytic anemia are listed in Table 8.1 ; they may be immune or nonimmune. Table 8.1 Causes of hemolytic anemia due to extracorpuscular defects. Immune Isoimmune Hemolytic disease of the newborn Incompatible blood transfusion Autoimmune IgG…
Hemolysis is a reduction in the normal red cell survival of 120 days. A general approach to diagnosing hemolytic anemia in the context of other causes of anemia is described in Chapter 3 , Classification and Diagnosis of Anemia in…
Bone marrow failure may manifest as a single cytopenia (e.g., erythroid, myeloid, or megakaryocytic) or as pancytopenia. It may present with a hypoplastic or aplastic marrow or result from invasion of the bone marrow by neoplastic or nonneoplastic (e.g., storage…
Lymphadenopathy Enlarged lymph nodes are commonly found in children. Lymphadenopathy might be caused by proliferation of cells intrinsic to the node, such as lymphocytes, plasma cells, monocytes, or histiocytes, or by infiltration of cells extrinsic to the node, such as…