Pediatric Examination and Board Review (155 page)

18.
(B)
Penicillin is the first choice for pneumococcal prophylaxis in patients with sickle cell disease, which is required because of the decreased splenic function and increased risk of sepsis from encapsulated organisms. Trimethoprim-sulfamethoxazole, rifampin, and fluconazole are not effective agents against
S pneumoniae
. In patients who are allergic to penicillin, erythromycin provides an option for prophylactic therapy.

19.
(D)
In patients with sickle cell disease, hydroxyurea induces erythroid regeneration and increased production of HbF. The drug is classified as an antimetabolite and antineoplastic agent. The exact mechanism of its antineoplastic activity has not been fully elucidated but is believed to be S-phase specific. The dose is titrated according to the patient’s blood counts, in particular the absolute neutrophil count. Beneficial effects of hydroxyurea can begin in the first few weeks after commencing therapy, and studies have shown that treatment can result in significantly fewer hospitalizations for pain, with shorter lengths of stay, compared with those receiving placebo. The role of hydroxyurea in the prevention of stroke in sickle cell disease is an area of active investigation. High transcranial flow velocities are associated with an increased risk of stroke in patients with sickle cell disease, and hydroxyurea therapy has been shown to decrease elevated transcranial flow velocities, suggesting it might serve as an alternative to chronic erythrocyte transfusions for primary stroke prophylaxis. Hydroxyurea is also an alternative to chronic transfusions for secondary stroke prophylaxis in children for whom transfusions cannot be continued safely (eg, erythrocyte allosensitization). The role of hydroxyurea in preserving organ function in sickle cell disease is not yet determined. Although the long-term risks and benefits of hydroxyurea are not known, current clinical experience has not identified any clear detrimental effects or safety concerns.

S
UGGESTED
R
EADING

American Academy of Pediatrics. Health supervision for children with sickle cell disease.
Pediatrics.
2002;109(3):526-535.

Embury SH, Vichinsky EP. Sickle cell disease. In: Hoffman R, Benz EJ, Shattil SJ, et al, eds.
Hematology
:
Basic Principles and Practice.
5th ed. Philadelphia, PA: Churchill Livingstone; 2008.

Heeney MM, Ware RE. Hydroxyurea for children with sickle cell disease.
Pediatr Clin North Am
. 2008;55(2):483-501.

Lane PA. Sickle cell disease.
Pediatr Clin North Am.
1996;43(3): 639-662.

CASE 90: A 14-YEAR-OLD BOY WITH A PAINFUL LEFT THIGH

A 14-year-old boy is brought to your office by his father for left leg pain. He had injured his left leg several weeks earlier playing football. He was not seen by a physician at the time of injury. The pain has persisted despite minimal activity since that time, and the pain has not been relieved with the use of ibuprofen.

He has been seen in your office since he was an infant, and he has no history of any medical problems. The family history is also negative for any significant medical problems. He has been doing well in school and had been active in sports before this injury, with no history of prior leg injuries.

On physical examination, he is well appearing with normal vital signs. His left leg appears grossly normal but is tender above the left knee. Radiographs reveal a lytic bone lesion in the distal left femur, with no fracture.

SELECT THE ONE BEST ANSWER

1.
The differential diagnosis of painful bony lesions in children includes all of the following except

(A) osteosarcoma

(B) Ewing sarcoma

(C) osteoid osteoma

(D) nonossifying fibroma

(E) osteomyelitis

2.
Which of the following sites within bones is the
most
common primary site for osteosarcoma?

(A) metaphysis

(B) diaphysis

(C) bone marrow

(D) epiphysis

(E) osteoblast

3.
The peak incidence of osteosarcoma occurs in which age range?

(A) 1-4 years

(B) 5-8 years

(C) 9-12 years

(D) 13-17 years

(E) first year of life

4.
Which of the following is not a risk factor for osteosarcoma?

(A) history of bilateral retinoblastoma

(B) history of prior radiation exposure

(C) Down syndrome

(D) family history of leukemia

(E) Li-Fraumeni syndrome

5.
Which of the following is the peak age range for diagnosis of patients with Ewing sarcoma?

(A) 1-5 years

(B) 5-10 years

(C) 10-20 years

(D) 20-30 years

(E) first year of life

6.
Which of the following is the least common site of Ewing sarcoma?

(A) femur

(B) ilium

(C) rib

(D) skull

(E) fibula

7.
Which of the following clinical features is least likely to distinguish osteosarcoma from Ewing sarcoma?

(A) fever

(B) tumor location

(C) radiographic appearance

(D) age of onset

(E) family history

8.
Which of the following is not a clinical feature of Langerhans cell histiocytosis?

(A) diabetes mellitus

(B) seborrheic dermatitis

(C) lytic bone lesions

(D) pancytopenia

(E) diabetes insipidus

9.
Which of the following is the least likely laboratory finding in patients with hemophagocytic lymphohistiocytosis?

(A) thrombocytopenia

(B) elevated alkaline phosphatase

(C) elevated serum triglycerides

(D) low serum fibrinogen

(E) anemia

10.
Which of the following blood products should
not
be used in pediatric patients with malignancies who are receiving chemotherapy?

(A) platelet apheresis units

(B) blood-type matched FFP

(C) packed red blood cells obtained from the patient’s siblings

(D) leuko-reduced or leuko-filtered red blood cells

(E) cryoprecipitate

11.
In which of the following clinical situations is a platelet transfusion least likely to be effective?

(A) correction of thrombocytopenia in a patient with acute idiopathic thrombocytopenia purpura (ITP)

(B) control of bleeding in a patient with Fanconi anemia

(C) preparation for a lumbar puncture in a patient recently diagnosed with leukemia

(D) treatment of an intracranial hemorrhage in a patient with Wiskott-Aldrich syndrome

(E) control of bleeding following chemotherapy

12.
In which of the following clinical situations is the use of FFP the most effective treatment option?

(A) persistent hemorrhage in a patient with hepatic insufficiency

(B) presurgical prophylaxis in a patient with hypofibrinogenemia

(C) correction of prolonged PTT in a patient receiving heparin therapy

(D) treatment of a hemarthrosis in a patient with hemophilia A

(E) patient with bleeding following chemotherapy

13.
Which of the following microorganisms cannot be acquired via blood product transfusions?

(A) cytomegalovirus

(B) hepatitis B virus

(C) influenza virus

(D) human immunodeficiency virus

(E)
Plasmodium vivax

14.
Features of patient reactions to red blood cell transfusions include all of the following except

(A) temperature higher than 101.3°F (38.5°C)

(B) myoglobinuria

(C) hyperbilirubinemia

(D) dyspnea

(E) rash

15.
Long-term complications of radiation therapy include all of the following except

(A) diabetes mellitus

(B) secondary amenorrhea