Peds Review: Blood/Neoplastic Disorders

Question 1An 8-week-old breastfed boy is brought to the clinic for his health supervision visit. His mother thinks he may be more pale than her other children, but he has otherwise been healthy. Findings on physical examination and vital signs are normal. He does not appear pale to you. A complete blood count reveals hemoglobin of 9 g/dL (90 g/L) and a mean cell volume of 85 fL. The remainder of the complete blood count is normal.

Of the following, the MOST appropriate recommendation for this infant is toa) administer a daily multivitamin and folic acidb) admit the infant for a packed red blood cell transfusionc) measure serum iron and transferrin concentrationsd) reassure the mother that the anemia will resolve Physiologic anemia of infancy (6 wks – 3months)e) switch feeding to an iron-fortified infant formula

Question 2A previously healthy 15-year-old girl returns from summer camp in the mountains complaining of dysuria, frequency, and urgency. You diagnose cystitis and prescribe trimethoprim-sulfamethoxazole. Her mother phones 3 days later to report that the girl is very tired and appears pale. You advise her mother to bring her to your office. On examination, she appears pale and your order laboratory tests. The girl's hemoglobin is 8.5 g/dL (85.0 g/L), a decrease from the value of 11.5 g/dL (115.0 g/L) that was measured during her pre-camp physical examination. Her reticulocyte count is 5.0% (0.050), and the red cell indices are normal except for mild microcytosis with a mean corpuscular volume of 76 fL. You review a smear

Of the following, the MOST likely cause of this girl's rapid onset of anemia isa) glucose-6-phosphate dehydrogenase deficiencyb) hemoglobin SC diseasec) hereditary elliptocytosisd) inadequate dietary irone) pyelonephritis

G6PD deficiency is the most common disease-producing enzymopathy in humans. Inherited as an X-linked disorder, primarily as single-base mutations in the G6PD locus at Xq28, G6PD deficiency affects 400 million people worldwide. The highest prevalence rates (with gene frequencies from 5% to 25%) are found in tropical Africa, the Middle East, tropical and subtropical Asia, some areas of the Mediterranean, and Papua New Guinea. The defect occurs in approximately 13% of African American males. Homozygous women are found in populations in which the frequency of G6PD deficiency is high. Heterozygous (carrier) women may develop hemolytic attacks. The gene confers some protection against malaria, which probably accounts for its high gene frequency in modern populations.

The G6PD enzyme catalyzes the oxidation of glucose-6-phosphate to 6-phosphogluconate while reducing the oxidized form of nicotinamide adenine dinucleotide phosphate (NADP+) to nicotinamide adenine dinucleotide phosphate (NADPH). NADPH, a required cofactor in many biosynthetic reactions, maintains glutathione in its reduced form.

Reduced glutathione is a scavenger for dangerous oxidative metabolites in the cell. Red blood cells depend on G6PD activity as the only protection against oxidative stresses. People deficient in G6PD, therefore, are at risk for hemolysis and its sequelae when exposed to oxidative stress. The degree of hemolysis varies with dose of the inciting agent.

The enzymatic defect in Americans of African descent is statistically less severe than that of people of Mediterranean descent. The enzyme also is found in lower quantities in older red blood cells due to senescence of the enzyme.

Affected individuals typically do not display symptoms or signs in the absence of oxidative stress. However, those who have very low enzyme concentrations may present with neonatal jaundice and acute hemolytic anemia. Neonatal jaundice usually appears by age 1 to 4 days, at the same time as or slightly earlier than so-called physiologic jaundice; kernicterus is rare. Acute hemolytic anemia results from stress factors such as oxidative drugs or chemicals, infection, or ingestion of fava beans (common to a Mediterranean diet).

Gallstones may be a prominent feature in affected individuals. As with hemolysis of different causes, jaundice and splenomegaly may be present during a crisis. Immediately after an episode, younger red blood cells are released that contain a higher concentration of enzyme. Accordingly, testing should be delayed in the event of undiagnosed hemolysis in children for a few weeks after the hemolysis to allow G6PD to decrease to normal concentrations.

The clinician should have a high suspicion for G6PD deficiency in immigrants of the ethnic groups noted previously and consider testing potentially affected males who exhibit hemolysis as part of a significant illness (such as diabetic acidosis, hepatitis) or trauma, especially prior to administering medications that may precipitate hemolysis. Precipitants include antibacterials (especially sulfonamides), antimalarials (chloroquine, primaquine), and other medications (aspirin, vitamin K analogs). Chemicals that may induce hemolysis include naphthalene, which is found in mothballs.

Question 3A newborn male experiences prolonged oozing following circumcision. Hematologic evaluation reveals that he has less than 1% of factor VIII clotting activity and a prolonged partial thromboplastin time, consistent with severe hemophilia A. His family history is negative for any individuals affected by clotting disorders.

Of the following, the MOST accurate statement for counseling this child's parents is thata) another family member likely is affected, but the condition is so mild that the person has not been diagnosedb) in families such as this, 50% of affected boys have a spontaneous gene mutationc) molecular genetic testing can detect mutations in 50% of affected individualsd) severe hemophilia is the rarest of all typese) there is an 80% chance that the mother is a hemophilia carrier

One third to one half of all males who have hemophilia A have no family history of the disorder, as described for the infant in the vignette. In these cases, it is important to recognize that multiple genetic scenarios can result in such an outcome.

In about 20% of the cases involving no previous family history for hemophilia, the mother is not a carrier, in which case her son has a de novo disease-causing mutation. In some of these situations, the son is a somatic mosaic for the mutation, ie, the mutation is not present in all of the cells of his body.

In 80% of such cases, the mother is a carrier, and she might have a de novo gene mutation. This mutation could have occurred in the egg or sperm cell from which she was conceived (in which case it is present in all of her cells). Alternatively, it may be due to a somatic mutation that occurred in early embryogenesis or to germline

mosaicism, in which case it is present in only some of her germ cells. The mother could have inherited the disease-causing mutation from her mother or unaffected father (if he is a somatic or germline mosaic). Finally, the mother could have inherited the mutation from a previous generation, which may have been passed on only through daughters, for example, so that no one was affected with hemophilia A.

Cases in which the mutation for hemophilia A is present in a mosaic state are unusual, and the gene mutation runs true in families. Therefore, every boy in a family who has the same mutation will have the same severity of disease.

Severe hemophilia (<1% normal factor VIII activity) is the most common of all types of hemophilia A. Molecular genetic testing can detect mutations in 98% of those who have severe disease.

Question 4When a 14-year-old girl had frequent complaints of shoulder pain made worse by pitching softball a few months ago, you diagnosed overuse injury. Nonsteroidal anti-inflammatory drugs and rest have provided some relief. She presents today with complaints of recurrent upper arm pain that is unrelated to exercise and sometimes awakens her from sleep. Physical examination reveals a slightly larger circumference of the left proximal humerus compared with the right. There is minimal tenderness on palpation over the area, although the girl reports a constant ache. She has full range of motion of the arm at the shoulder and elbow. You obtain a shoulder radiograph Of the following, the MOST likely diagnosis is

a) acromioclavicular separationb) acute osteomyelitisc) chronic osteomyelitisd) osteosarcomae) supracondylar fracture of the humerus

The differential diagnosis of bone pain and swelling includes stress fracture, hematoma, bone cysts, and other bony tumors such as Ewing sarcoma.Initial evaluation of an adolescent or older child presenting with bone pain and swelling, especially with a palpable mass, should include:

Plain radiographs (two views) of the suspected lesions, although no single feature on radiographs is diagnostic. Osteosarcomatous lesions can be purely osteolytic (about 30% of patients), purely osteoblastic (about 45% of patients), or a mixture of both. Elevation of the periosteum may appear as the characteristic Codman triangle. Extension of tumor through the periosteum may result in a so-called "sunburst appearance" (about 60% of patients).

Both magnetic resonance imaging of the primary lesion and computed tomography scan of the chest are necessary to confirm the diagnosis and for staging purposes. Such scans frequently are performed at the tertiary center using their protocols.

Question 5You are treating a 2-year-old girl who has suspected meningococcal bacteremia and meningitis. Over the past 2 hours, she has required multiple fluid boluses and inotropic support to help maintain her blood pressure. She has been intubated due to respiratory failure. Her temperature is 96°F (35.6°C), and she is covered in a petechial and purpuric rash (Item Q44A). Her most recent laboratory results reveal a white blood cell count of 1.2x103/mcL (1.2x109/L) with 80% lymphocytes, 10% neutrophils, and 10% band forms and a platelet count of 32x103/mcL (32x109/L).

Of the following, the MOST important additional laboratory test isa) erythrocyte sedimentation rateb) measurement of creatine kinasec) measurement of fibrinogend) measurement of lactic acide) review of peripheral blood smear

Question 6A male infant is born without a right thumb. Laboratory testing reveals a platelet count of 60 x 103/mcL (60 x 109/L). There is no evidence of bleeding.Of the following, the BEST management of this patient is

a) bone marrow biopsyb) computed tomography of the headc) genetics consultationd) intravenous corticosteroid therapye) intravenous immunoglobulin G

The newborn who has thrombocytopenia may be at risk for spontaneous hemorrhage, especially if platelet counts decrease to less than 10 to 15 x 103/mcL (10 to 15 x 109/L). Thrombocytopenia may be associated with numerous chromosomal and genetic syndromes, and one of the most readily discernible is the thrombocytopenia-absent radius (TAR) syndrome (Item C196A). Affected patients have bilateral absence of the radius, abnormal carpal bones and phalanges, clubbed hands, or phocomelia. Thumbs typically are present. Additionally, the thrombocytopenia in infants who have TAR becomes apparent in the first week after birth with spontaneous hemorrhage (90% of patients are symptomatic by 4 months of age). Intracranial hemorrhage may be present with seizure, lethargy, poor feeding, apnea, or hemodynamic collapse. The symptomatic patient should have platelet counts evaluated and imaging of the central nervous system (eg, computed tomography). Petechiae are common, and any procedure that could be associated with bleeding (eg, circumcision, phlebotomy) should be avoided. The thrombocytopenia is associated with a hyporegenerative marrow that is unresponsive to corticosteroids or intravenous immunoglobulin G. Bone marrow aspiration is both risky and unnecessary. Thrombopoietin levels are normal to elevated.

Management of infants who have TAR syndrome includes avoidance of trauma and elective surgeries and maintaining a platelet count greater than 15 x 103/mcL (15 x 109/L) using platelet transfusions. The thrombocytopenia typically is self-limited, with normal platelet counts being established by age 2 years. The limb anomalies require physical therapy, occupational therapy, pediatric orthopedic and physical medicine consultation, and rehabilitation over a number of years. Genetics consultation is required because some cases of TAR syndrome are autosomal recessive, and recurrence risks should be addressed.

Question 7An 18-month-old infant presents with a skin eruption that consists of discrete red, orange, and yellow-brown papules (Item Q2A). On physical examination, you note scaling dermatitis of the scalp, postauricular, perineal, and axillary areas. A skin biopsy reveals CD1a-positive monocyte macrophages that contain Birbeck granules.

Of the following, the MOST likely diagnosis for this infant is

a) acute monocytic leukemiab) familial erythrophagocytic lymphohistiocytosisc) infection-associated hemophagocytic syndromed) Langerhans cell histiocytosise) malignant histiocytosis

The infant described in the vignette exhibits physical findings and skin biopsy characteristics consistent with Langerhans cell histiocytosis (LCH). The name of LCH has been applied to the class I histiocytoses (Item C2A), previously known as histiocytosis X, and includes the clinical entities of eosinophilic granuloma, Hand-Schüller-Christian disease, and Letterer-Siwe disease. The normal Langerhans cell is an antigen-presenting cell of the skin. The hallmark of LCH is the Birbeck granule (Item C2B), a tennis racket-shaped bilamellar granule, which when seen in the cytoplasm of lesional cells in LCH, is diagnostic of the disease. Alternatively, LCH can be diagnosed definitively by demonstrating CD1a (surface markers on T cells) positivity of lesional cells.

Class II histiocytoses are characterized by accumulation of antigen-processing cells (ie, macrophages). These phagocytic cells lack the two class I markers (Birbeck granules and CD1a positivity) characteristic of LCH cells. The two major diseases of class II histiocytoses are familial erythrophagocytic lymphohistiocytosis and infection-associated hemophagocytic syndrome. In both diseases, disseminated lesions involve many organ systems. The lesions are characterized by infiltration of the involved organ with activated phagocytic macrophages and lymphocytes.

Class III histiocytoses are characterized by neoplastic proliferation of cells that have characteristics of monocytes/macrophages or their precursors. Acute monocytic leukemia and malignant histiocytosis are included in this category. In both conditions, Birbeck granules are absent, and cells are CD1a negative.

Question 8An 18-month-old girl comes to your clinic with her mother, who reports that the girl has seemed pale over the last week. The mother explains that there has been no fever, change in appetite, or weight loss. The girl has been healthy, but she always has been a “picky eater”. On physical examination, you find an alert girl who has marked conjunctival pallor. Her weight is at the 24th percentile, and her heart rate is 160 beats/min. There is no hepatosplenomegaly. You note a c-cm bruise on her left buttock and several smaller bruises on her upper arms and abdomen. Findings on the remainder of her examination are within normal limits.

Of the following, the MOST likely diagnosis isa) acute lymphoblastic leukemiab) child abusec) immune thrombocytopenic purpurad) iron-deficiency anemiae) transient erythroblastopenia of childhood

The clinical features of pallor and bruising in the child described in the vignette suggest anemia and thrombocytopenia. In such a case, when two cell lines appear to be affected, an impairment of normal bone marrow function (ie, erythropoiesis and thrombopoiesis) is likely. Viral infections are a common cause of bone marrow suppression in children. IN addition, any disease that affects the bone marrow can cause marrow failure, including aplastic anemia, myelofibrosis, and leukemias and other malignancies, such as neuroblastoma. Therefore, of the conditions listed, the most likely diagnosis in this child is acute lymphoblastic leukemia.

Children who have acute lymphoblastic leukemia typically present with symptoms suggestive of bone marrow failure, with the involvement of more than one cell line, as well as bone and joint pain lymphadenopathy, and organomegaly. Occasionally, affected children present with an abnormality of only one cell line, such as neutropenia or thrombocytopenia. Lymphoblasts may be seen on peripheral smear, but the absence of these cells does not rule out the diagnosis. A bone marrow examination and biopsy are necessary to make the diagnosis.

Child abuse should be suspected in any child who presents with bruising in atypical areas of the body, such as the trunk, face, or buttocks. However, marked pallor would not be seen unless massive bleeding from occult trauma was present. Immune thrombocytopenic purpura is a common cause of bruising in young children. Hemoglobin levels typically are normal in this disease; mild anemia due to bleeding may be present, but it is not severe enough to cause significant pallor. Iron-deficiency anemia and transient erythroblastopenia of childhood are diseases that affect only the erythroid cell line, so bruising is not present.

Question 9A 15-month-old infant has been breastfed since birth. He eats finger foods (eg, peas, carrots) and occasionally some cereal. His mother adheres to a vegan diet and plans the same for her child. A complete blood count documents anemia.Of the following, the MOST likely cause of this infant’s anemia is a deficiency of

a) folic acidb) niacinc) riboflavind) thiaminee) vitamin B12

The infant described in the vignette has been exclusively breastfed by a strict vegan mother and is at risk for anemia due to vitamin B12 deficiency. The appearance of hypersegmented neutrophils in the peripheral blood precedes the development of classic megaloblastic (macrocytic) anemia. The infant’s deficiency may be caused by reduced placental transfer of vitamin B12 in utero and lower vitamin content in the mother’s milk. In addition, the infant is being offered other foods that are consistent with a vegan diet and contain little vitamin B12. Deficiency of vitamin B12, including dietary deficiency, is unusual in infants and children in the United States. Other causes of deficiency are pernicious anemia; impaired gastric and small bowel absorption, including resections; and rare inherited metabolic disorders such as methylmalonic aciduria and intrinsic factor deficiency. Vitamin B12 deficiency is diagnosed by recognition of risk factors, documentation of low serum B12 concentrations in the infant, and a subsequent response to treatment. Demonstration of low serum vitamin B12 values in the mother supports the diagnosis.

Folic acid deficiency is an unlikely cause of the anemia for the infant described in the vignette. Folate is present in many foods consumed by vegans, and human milk provides adequate folate for the breastfed infant. Folate deficiency rarely is present in newborns because the fetus extracts adequate folate from the mother, even in the presence of maternal deficiency. Defects of folate metabolism are rare, although infants exclusively fed goat milk are at risk for folate deficiency and possible megaloblastic anemia. A diagnosis of folate deficiency should be confirmed, including the exclusion of vitamin B12 deficiency, before initiating folate replacement therapy. Treatment with therapeutic doses of folate may delay the diagnosis of vitamin B12 deficiency and increase the risk of neurologic complications. Erythrocyte folic acid concentration is a better measure of folate sufficiency than serum folate concentrations.

Deficiencies of thiamine (vitamin B1), riboflavin (vitamin B2), and niacin (vitamin B3) are rare and not associated with anemia. Thiamine deficiency is associated with beriberi (cardiomyopathy, peripheral neuropathy, and encephalopathy). Riboflavin deficiency is associated with cheilosis and glossitis. Pellagra (dementia, diarrhea, and dermatitis) is associated with niacin deficiency.

Question 10You are asked to see a 7-year-boy in whom medulloblastoma (primitive neuroectodermal tumor) was diagnosed at age 3 years. Treatment at that time consisted of chemotherapy and craniospinal irradiation. During the past year, he grew 2 cm, although he is eating normally, and his weight is appropriate for height. Despite spinal irradiation, the upper-to-lower segment ratio is normal for his age.

Of the following, the MOST likely diagnosis isa) acquired growth hormone deficiencyb) chemotherapy-induced renal failurec) Cushing syndromed) irradiation-induced epiphyseal fusione) tumor recurrence

Question 11You are seeing a 30-year-old multigravid woman for prenatal counseling. She has had immune thrombocytopenic purpura for the past 5 years, and her spleen was removed 2 years ago. She asks you about the effects that her disease might have on her unborn child.

Of the following, you are MOST likely to tell her thata) if her newborn has thrombocytopenia, he or she will be treated with intravenous immunoglobulinb) maternal platelet counts predict fetal risks of intracranial hemorrhagec) maternal platelet transfusion during pregnancy will minimize the risk for neonatal thrombocytopeniad) operative delivery of the newborn will reduce the risk of intracranial hemorrhagee) the newborn will require a platelet transfusion soon after birth

Question 12A 6-year-old child presents for a health supervision visit. On physical examination, his weight is 18 kg and height is 102 cm (<3rd percentile), his pulse rate is 90 beats/min, respiratory rate is 18 breaths/min, and blood pressure is 134/88 mm Hg. Of note, he has pale conjunctivae and mild edema. Among the results of laboratory evaluation are:

Hemoglobin, 7.5 g/dL (75 g/L) White blood cell count, 6x103/mcL (6x109/L) Platelet count, 275x103/mcL (275x109/L) Mean cell volume, 82 fL Reticulocyte count, 0.4% (0.004) Blood urea nitrogen, 94 mg/dL (33.6 mmol/L) Serum creatinine, 12.1 mg/dL (1,070 mcmol/L)

The stool is negative for occult blood.

Of the following, the MOST likely explanation for this patient's anemia isa) chronic gastrointestinal blood lossb) erythropoietin deficiencyc) folic acid deficiencyd) hemolysise) iron deficiency

Question 13A 6-month-old girl, who was born in Nigeria, presents for an urgent visit as soon as the family arrives in the United States because of fever and irritability. Physical examination reveals a fussy infant who has anorexia, a temperature of 100°F (37.8°C), and swelling of all of the fingers of the right hand (Item Q228). The remainder of the examination findings are negative.

Of the following, the MOST likely cause of this pattern of swelling in this child isa) cellulitisb) juvenile idiopathic arthritisc) malariad) sickle cell diseasee) trauma