MCQs In Pediatric Oncology>

Q1:

You identify a right-sided abdominal mass in a 2-month-old girl during a health supervision visit. The mass is firm but not tender. Abdominal ultrasonography reveals a solid mass pushing the right kidney downward. Abdominal radiography reveals no calcifications in the mass.

Of the following, the MOST likely diagnosis is:

A. adrenocortical carcinoma

B. hepatoblastoma

C. neuroblastoma

D. rhabdomyosarcoma

E. Wilms tumor

The primary site of neuroblastoma most commonly is the adrenal gland. Ultrasonography reveals a suprarenal mass displacing the kidney downward but not altering its intrinsic architecture, as described for the child in the vignette. 

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Q2 

A 7-year-old boy presents with bruising, pallor, intermittent "achy" pain in the extremities, and intermittent low-grade fever of 2 weeks' duration. Findings on laboratory studies include: hemoglobin, 5.5 g/dL (55 g/L); white blood cell count, 2,100/cu mm (2.1 x 109/L); mean corpuscular volume, 76 fL; lactate dehydrogenase, 230 IU/L; and uric acid, 5.5 mg/dL (327 mcmol/L).

Of the following, the MOST likely diagnosis is:

A. acute lymphoblastic leukemia

B.  aplastic anemia

C.  Fanconi anemia

D.  infectious mononucleosis

E.  parvovirus infection

Answer

A

Acute lymphoblastic leukemia (ALL) and aplastic anemia usually present with purpura and pallor, and it is critical to be able to differentiate between these life-threatening disorders. ALL is much more common and often presents with additional signs and symptoms. Hepatosplenomegaly occurs in more than 60% of patients; lymphadenopathy in more than 50%; and bone pain, onset of a limp, or refusal to walk in as many as 40%. Arthralgias arising from joint infiltration can imitate juvenile rheumatoid arthritis. Fever occurs in more than 50% of children and is more often due to the disease than to secondary infection. Respiratory distress due to superior vena cava syndrome is seen, particularly in adolescents. Occasional patients present with symptoms of increased intracranial pressure due to central nervous system involvement.

            An elevated white blood cell count, almost always associated with blasts in the peripheral blood, is an obvious sign of leukemia. However, as many as 50% of patients have a normal white blood cell count at diagnosis. Those who have the lowest counts may not demonstrate blasts in the peripheral blood, making the differentiation from aplastic anemia difficult, especially in the absence of other clinical signs. Children who have ALL and low white blood cell counts have lower tumor burdens. They have less lymphadenopathy and organomegaly and are more likely to have normal uric acid levels. In children who report bone pain, radiographs may identify typical leukemic changes, especially around the knees, wrists, and ankles, but the pain may be present without radiologic findings.

Acute myelogenous leukemia (AML) accounts for 15% to 20% of childhood leukemias. The clinical presentation is similar to ALL, but skin, gum, and central nervous system involvement are more common. Patients who have high white blood cell counts can develop life-threatening central nervous system disease due either to hemorrhage or cerebral leukostasis

.Inherited bone marrow failure syndromes are an important consideration because manifestations of these disorders may be apparent upon physical examination. Fanconi anemia, an autosomal recessive disorder, is most common. Approximately 80% of affected patients manifest physical abnormalities, including hyperpigmentation, short stature, abnormal upper limbs (particularly thumbs), hypogonadism, a small face, and typical facies. Although the physical findings are evident at birth, the pancytopenia usually is not evident until an average age of 8 years. Several other congenital disorders have been associated with bone marrow failure, but these are very rare. They include dyskeratosis congenita, Shwachman-Diamond syndrome, and reticular dysgenesis.

            Myelodysplastic syndromes are uncommon in children, but at presentation they can be confused easily with leukemia or aplastic anemia. Affected patients may present with involvement of any single or multiple cell lines. Clues to the underlying diagnosis include the presence of nucleated erythrocytes, tear drop-shaped erythrocytes, and relatively small numbers of immature white blood cells in peripheral blood. The bone marrow is hypercellular, with disordered and morphologically abnormal maturation of cell lines. Approximately 50% of patients have a clonal chromosomal abnormality that often involves chromosome 7. Most affected children progress to leukemia or die of bone marrow failure.

            Parvovirus infection causes transient erythroid hypoplasia, but this usually becomes clinically significant only in patients who have underlying hemolytic anemias