ABP Pediatric Hematology-Oncology key terms

Anemia in which circulating red blood cells are smaller than normal for age, reflected by a low mean corpuscular volume. Common pediatric causes include iron deficiency, thalassemia, lead toxicity, and chronic inflammation.

The most common childhood anemia, caused by insufficient iron for hemoglobin synthesis. It progresses from iron depletion to iron-deficient erythropoiesis to anemia, producing microcytosis, hypochromia, and low ferritin.

A calculated ratio of mean corpuscular volume divided by red blood cell count, used to distinguish iron deficiency from thalassemia trait. Values below 13 favor thalassemia; values above 13 favor iron deficiency.

The most severe form of alpha thalassemia, in which all four alpha globin genes are deleted. Fetuses develop profound anemia, heart failure, edema, and usually die before or shortly after birth without transfusion.

A group of inherited hemoglobin disorders caused by the sickle beta-globin mutation, in which deoxygenated hemoglobin S polymerizes and distorts red cells. This produces hemolytic anemia, vaso-occlusion, and episodic pain.

A life-threatening complication of sickle cell disease defined by a new pulmonary infiltrate with fever or respiratory symptoms. It is a leading cause of death and requires prompt antibiotics, oxygen, and often exchange transfusion.

Sudden trapping of blood in the spleen in young children with sickle cell disease, causing rapid anemia, splenomegaly, and hypovolemic shock. Parents are taught splenic palpation; treatment includes cautious transfusion and possible splenectomy.

Bone marrow failure with hypocellular marrow and pancytopenia in the absence of an infiltrating disease or marrow fibrosis. Most pediatric cases are acquired and immune-mediated; inherited syndromes must be excluded.

An inherited bone marrow failure syndrome caused by defective DNA repair, with progressive pancytopenia, congenital anomalies such as radial defects, and markedly increased risk of leukemia and squamous cell carcinoma.

A congenital pure red cell aplasia presenting in infancy with severe anemia, reticulocytopenia, and absent erythroid precursors in marrow. It is usually treated with corticosteroids or transfusions and is linked to ribosomal gene mutations.

An acquired clonal disorder in which red cells lack CD55 and CD59, making them unusually sensitive to complement-mediated destruction. It causes intravascular hemolysis, hemoglobinuria, thrombosis, and sometimes marrow failure.

An X-linked enzyme deficiency that impairs the red cell's ability to regenerate NADPH and withstand oxidative stress. Exposure to infection, fava beans, or certain drugs triggers hemolysis with bite cells and Heinz bodies.

An inherited red cell membrane defect, usually involving spectrin or ankyrin, that produces spherical, fragile cells trapped in the spleen. Features include hemolytic anemia, splenomegaly, jaundice, and pigment gallstones.

Also called the Coombs test; it detects antibodies or complement bound to a patient's red cells. A positive result supports immune-mediated hemolysis, such as autoimmune hemolytic anemia or a delayed transfusion reaction.

An X-linked bleeding disorder caused by deficient or dysfunctional coagulation factor VIII. Severity depends on residual activity; children present with spontaneous or post-traumatic joint and muscle bleeds.

The most common inherited bleeding disorder, caused by quantitative or qualitative abnormalities of von Willebrand factor. It impairs platelet adhesion and also reduces factor VIII stability, producing mucocutaneous bleeding such as epistaxis and menorrhagia.

An acquired autoimmune disorder in which antibodies destroy platelets, causing isolated thrombocytopenia with a normally cellular marrow. Children usually present with sudden bruising or petechiae and most recover spontaneously.

A clotting test that measures the intrinsic and common pathways. It is prolonged in factor VIII, IX, XI, and XII deficiencies and is used to monitor unfractionated heparin therapy.

A standardized ratio that adjusts prothrombin time for the sensitivity of the thromboplastin reagent. It is used to monitor warfarin therapy and to assess the extrinsic pathway of coagulation.

An acquired thrombophilia defined by thrombosis or pregnancy morbidity plus persistent antiphospholipid antibodies, such as lupus anticoagulant or anticardiolipin. In children it may cause venous or arterial thrombosis and stroke.

The most common childhood malignancy, arising from clonal proliferation of lymphoid precursors in marrow and extramedullary sites. Treatment uses risk-adapted multiagent chemotherapy with central nervous system prophylaxis; prognosis now exceeds 90 percent.

Low-level leukemia detectable by flow cytometry or polymerase chain reaction when morphology shows remission. Measured at defined time points, it is the strongest independent predictor of relapse and guides treatment intensification.

A translocation between chromosomes 9 and 22 that creates the BCR-ABL1 fusion gene and constitutive tyrosine kinase activity. It defines chronic myeloid leukemia and occurs in a subset of acute lymphoblastic leukemia.

A metabolic emergency caused by rapid destruction of malignant cells, producing hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia. It can cause acute kidney injury and arrhythmias and is prevented with hydration and rasburicase.

A lymphoid malignancy with characteristic Reed-Sternberg cells, usually presenting as painless cervical or mediastinal lymphadenopathy in adolescents. Staging and response assessment guide combined chemotherapy with or without radiation.

An embryonal tumor of sympathetic nervous system origin, most often arising in the adrenal medulla of young children. It frequently secretes catecholamines and can present with bone pain, proptosis, or opsoclonus-myoclonus.

The most common pediatric renal cancer, typically presenting as an asymptomatic abdominal mass in children under five. It is associated with WT1 mutations and syndromes such as WAGR and Beckwith-Wiedemann.

The most common primary bone cancer in adolescents, often arising near the knee with pain and swelling. Treatment combines neoadjuvant chemotherapy with limb-sparing surgery, and pulmonary metastases are common.

An embryonal tumor of the cerebellum and the most common malignant pediatric brain tumor. It often presents with headache, vomiting, and ataxia; treatment includes surgery, craniospinal radiation, and chemotherapy.

Fever in a patient with severe neutropenia, treated as an emergency because of the risk of rapidly progressive bacterial sepsis. Blood cultures are obtained and empiric broad-spectrum antibiotics started immediately.

An immune attack by donor T cells against recipient tissues after allogeneic transplant, affecting skin, gut, and liver. Acute disease occurs within months; chronic disease resembles autoimmune or scleroderma-like illness.

The point after hematopoietic stem cell infusion when donor cells begin producing blood cells, usually defined by sustained neutrophil and platelet recovery. It marks restoration of marrow function and is monitored with daily counts.

Noncardiogenic pulmonary edema developing within hours of transfusion, caused by donor antibodies injuring recipient pulmonary endothelium. It presents with dyspnea, hypoxemia, and bilateral infiltrates and is managed with supportive oxygen.

Use of agents such as deferasirox or deferoxamine to bind and excrete excess iron acquired from repeated transfusions. It prevents cardiac, hepatic, and endocrine toxicity and is monitored with ferritin and liver iron measurements.

Dose-dependent heart muscle injury from doxorubicin or daunorubicin, ranging from asymptomatic systolic dysfunction to cardiomyopathy. Risk rises with cumulative dose, younger age, and chest radiation; survivors need lifelong echocardiographic monitoring.

A clinicoradiologic syndrome of headache, seizures, visual changes, and hypertension with white matter edema, often triggered by chemotherapy, corticosteroids, or calcineurin inhibitors. Recognition and blood pressure control usually lead to recovery.

Interdisciplinary care focused on relieving physical, emotional, social, and spiritual suffering and improving quality of life for children with serious illness and their families. It is appropriate from diagnosis alongside curative treatment.

A child's informed agreement to participate in treatment or research, obtained alongside parental permission. Its scope reflects the child's developmental capacity, and dissent should be respected whenever possible.

Counseling and interventions offered before gonadotoxic therapy to protect future reproductive function. Options in children include sperm banking after puberty and ovarian or testicular tissue cryopreservation, ideally within a research protocol.