Pediatric Examination and Board Review (158 page)

3.
Which of the following interventions is indicated for this patient at this time?

(A) intravenous antibiotics

(B) intravenous erythropoietin

(C) oral diuretic therapy

(D) subcutaneous heparin

(E) intravenous gammaglobulin

4.
Which of the following features of this patient’s presentation places her at highest risk for treatment failure?

(A) gender

(B) white blood cell count

(C) age

(D) physical examination

(E) platelet count

5.
What is the likelihood of a child with standard-risk acute lymphoblastic leukemia entering remission after the first month of induction therapy?

(A) 5-10%

(B) 20-30%

(C) 30-50%

(D) 50-60%

(E) 90-95%

6.
Which of the following increased serum laboratory values is not a feature of tumor lysis syndrome?

(A) uric acid

(B) calcium

(C) creatinine

(D) potassium

(E) phosphorus

7.
Measures to prevent the complications of tumor lysis syndrome include all of the following except

(A) intravenous hydration

(B) urine alkalinization

(C) xanthine oxidase inhibition

(D) intravenous potassium phosphate

(E) intravenous uricase

8.
Which of the following is not a risk factor for development of childhood leukemia?

(A) previous treatment with chemotherapy

(B) ataxia-telangiectasia

(C) maternal cocaine use during pregnancy

(D) Down syndrome

(E) Li-Fraumeni syndrome

9.
Which of the following is the least likely site of leukemia relapse?

(A) bone marrow

(B) cerebrospinal fluid (CSF)

(C) testes

(D) liver

(E) ovaries

10.
The best option for
Pneumocystis jiroveci
prophylaxis in this patient is which of the following?

(A) intravenous dapsone

(B) intravenous pentamidine

(C) oral trimethoprim-sulfamethoxazole

(D) intramuscular penicillin

(E) aerosolized pentamidine

11.
Which of the following immunizations is contraindicated in patients receiving chemotherapy?

(A) measles-mumps-rubella (MMR)

(B) tetanus-diphtheria (Td)

(C)
H influenzae
type b

(D) inactivated poliomyelitis vaccine (IPV)

(E) varicella vaccine

12.
Which of the following white counts represent neutropenia?

(A) WBC 8500; 51% neutrophils

(B) WBC 2000; 89% neutrophils

(C) WBC 16,000; 10% neutrophils

(D) WBC 5000; 15% neutrophils

(E) WBC 9000; 30% neutrophils

13.
Which of the following intravenous antibiotic regimens is least effective empiric therapy for febrile patients with neutropenia?

(A) ceftazidime

(B) vancomycin

(C) nafcillin and gentamicin

(D) meropenem

(E) vancomycin and ceftazidime

14.
Which of the following is the least common type of infection in patients with an absolute neutrophil count less than 500?

(A) gingivitis

(B) cellulitis

(C) bacterial pneumonia

(D) bacterial meningitis

(E) typhlitis

15.
Features of Shwachman-Diamond syndrome include all of the following except

(A) protein malabsorption

(B) cyclic neutropenia

(C) metaphyseal dysostosis

(D) elevated risk of aplastic anemia

(E) pancreatic deficiency

16.
Which of the following procedures is contraindicated in patients with severe neutropenia?

(A) lumbar puncture

(B) peripheral venous blood sampling

(C) throat culture

(D) rectal temperature

(E) bone marrow aspiration and biopsy

17.
Which of the following is not an acceptable management option for the management of a varicellanaive patient receiving chemotherapy who develops a new varicella infection?

(A) intravenous immunoglobulin

(B) intravenous acyclovir

(C) intravenous ribavirin

(D) isolation precautions

(E) hospitalization

ANSWERS

1.
(B)
The presence of cytopenias with blast forms on the peripheral smear is characteristic of acute leukemia. Leukemias are the most common form of childhood cancer and account for approximately a third of all pediatric malignancies. There are approximately 3000 new cases of pediatric leukemia each year in the United States, which occur in all races and equally in boys and girls. Approximately 75% of new leukemias are acute lymphoblastic leukemia; approximately 20% are acute myeloid leukemia. The peak age of onset of acute leukemia in children is between 2 and 5 years of age. The underlying etiology of acute leukemias in children is generally unknown, although there is an increased risk of acute leukemia in children with syndromes such as Down syndrome, Bloom syndrome, Fanconi syndrome, and ataxia-telangiectasia. Symptoms of acute leukemias in children are generally related to the cytopenias with bleeding, easy bruising, and petechiae from thrombocytopenia, pallor and fatigue from anemia, and fevers and infections from functional neutropenia. Children with acute leukemia also frequently have diffuse lymphadenopathy, hepatosplenomegaly, and bone pain with limping or refusal to walk.

Aplastic anemia can present with the acute onset of pancytopenia but does not have associated peripheral white blood cell blasts. Aplastic anemia can be either acquired or congenital, such as with Fanconi syndrome. Potential causes of acquired aplastic anemia include environmental toxins, infections, and prior radiation therapy or chemotherapy. Treatment requires either immunosuppression or bone marrow transplantation. ITP is characterized by isolated thrombocytopenia with no other blood count abnormalities, whereas hemolytic uremic syndrome, or HUS, is usually secondary to a prodromal diarrheal illness, followed by renal failure, anemia, and thrombocytopenia.

2.
(D)
The initial workup of a patient with leukemia includes a chest radiograph to rule out an underlying mediastinal mass with the possibility of airway compromise. Furthermore, bone marrow evaluation and a lumbar puncture are required for evaluation of the patient’s disease status. In general, the bone marrow in cases of acute leukemia is filled with more than 80% leukemic blasts and severely decreased numbers of precursors for other types of blood cells. In the absence of peripheral neurologic symptoms, a spinal MRI is not indicated. Approximately 5-10% of new cases of acute leukemia have leukemic blasts present in the CSF at diagnosis and rarely can have symptoms such as headache or cranial nerve palsies; but the presence or absence of leukemic blasts in the spinal fluid cannot be determined by imaging.

3.
(A)
Any patient with fever and neutropenia requires urgent intravenous antibiotic therapy. A patient with new acute leukemia, although potentially having a normal absolute neutrophil count, likely has few functional neutrophils and is therefore functionally neutropenic and at high risk for serious bacterial infections. This patient would benefit from blood and platelet transfusions at this time, but there is no indication for starting erythropoietin. Furthermore, diuresis and anticoagulation are not indicated at this time.

4.
(B)
Initial risk groups for pediatric leukemia are based on patient age and total white blood cell count. The patient’s white blood cell count of more than 50,000/μL places her in the high-risk category for acute lymphoblastic leukemia (ALL). Girls with ALL tend to have a slightly higher survival rate than boys, although gender is not a feature used to determine the initial risk groups for treatment purposes. Patients younger than 1 year of age or older than 10 years of age are considered “high risk” and require more intensive therapy. Physical examination features have no prognostic significance for ALL outcomes. Other prognostic features include cellular ploidy (with hypodiploid leukemias having a worse outcome) and other chromosomal abnormalities, such as the Philadelphia chromosome [t(9;22) bcr-abl translocation], which are associated with a worse outcome.

5.
(E)
The likelihood of remission after induction therapy for standard risk ALL in a child is more than 90%. The current likelihood of a long-term “cure” is approximately 70-80%, with lower survival for higher risk patients, patients with relapsed disease, and for those with acute myeloid leukemia.

6.
(B)
Tumor lysis syndrome, which most commonly occurs in leukemias and rapidly growing lymphomas, can occur both before and after therapy is initiated. The rapid cellular turnover in these types of tumors results in the release of large amounts of intracellular breakdown products and electrolytes into the blood. Features of tumor lysis include increases in serum uric acid, potassium, phosphorus, lactate dehydrogenase (LDH), and aspartate aminotransferase (AST). Calcium levels are frequently low because of the elevated phosphorus levels and can result in anorexia, vomiting, muscle cramps or spasms, tetany, and seizures. Uric acid and calcium phosphate can precipitate in renal tubules and cause renal insufficiency, resulting in elevation of the serum creatinine level.

7.
(D)
The management of tumor lysis syndrome includes aggressive hydration with intravenous fluids, urine alkalinization, and decreasing uric acid levels. The goals of hydration and alkalinization are to maintain good urine output and prevent precipitation of uric acid within the renal tubules. Inhibition of xanthine oxidase (which generates uric acid from nucleic acid metabolism) with allopurinol or direct metabolism of uric acid with intravenous urate oxidase decreases the serum levels of uric acid and decreases the risk of renal obstruction. Uricase is an alternative to allopurinol and reserved for patients who are at high risk for developing tumor lysis syndrome. It is a synthetic urate oxidase enzyme and acts by degrading uric acid. Treatment of increases in potassium and phosphorus with diuretics or medications such as insulin, calcium gluconate, or sodium polystyrene are also indicated as needed. Potassium and phosphorus should not be added to intravenous fluids because of the already increased levels in patients with tumor lysis syndrome and the potential for associated renal insufficiency. Dialysis for severe renal insufficiency may be required in some cases.

8.
(C)
Risk factors for the development of childhood leukemia include prior chemotherapy with either alkylating agents or topoisomerase inhibitors, both of which increase the incidence of secondary malignancies. Alkylating agents such as cyclophosphamide are associated with an increased risk of leukemias, usually within 5 years of exposure. Topoisomerase inhibitors such as etoposide are associated with an increased risk of myeloid malignancies, usually within 2 years. Ataxia-telangiectasia is a tumor predisposition syndrome associated with an increased risk of leukemias. Down syndrome is associated with a risk of transient myeloproliferative disorder (TMD), a neonatal leukemia-like proliferation of white blood cells that will spontaneously resolve without therapy. Unfortunately, in 20% of cases of TMD, true leukemia develops later in childhood, and patients with Down syndrome have a 500-fold increased risk of the M7 subtype of acute myelogenous leukemia compared with normal children. No linkage has been demonstrated between maternal illicit drug use during pregnancy and an increased incidence in childhood leukemia.