A 5-year-old girl is brought to the office by her mother and the mother's boyfriend due to leg pain. One week ago, the boyfriend saw the patient fall onto the living room floor after climbing on a couch. Since the incident, she has had persistent leg pain that appears to be worse at night, and for the last 2 days she has been refusing to walk, asking her mother to carry her. The patient has no chronic medical conditions but has had a mild, nonproductive cough for the past month. Temperature is 38.3 C (100.9 F); all other vital signs are normal. Height and weight are at the 20th percentile. Examination shows a pale child. The abdomen is nontender and the liver is palpated 3 cm below the costal margin. Palpation of the bilateral anterior proximal tibias elicits pain. There are a few scattered bruises across the chest and back. The remainder of the examination shows no abnormalities. Complete blood count results are as follows: Which of the following is the most likely cause of this patient's symptoms?

Question

A 5-year-old girl is brought to the office by her mother and the mother's boyfriend due to leg pain.  One week ago, the boyfriend saw the patient fall onto the living room floor after climbing on a couch.  Since the incident, she has had persistent leg pain that appears to be worse at night, and for the last 2 days she has been refusing to walk, asking her mother to carry her.  The patient has no chronic medical conditions but has had a mild, nonproductive cough for the past month.  Temperature is 38.3 C (100.9 F); all other vital signs are normal.  Height and weight are at the 20th percentile.  Examination shows a pale child.  The abdomen is nontender and the liver is palpated 3 cm below the costal margin.  Palpation of the bilateral anterior proximal tibias elicits pain.  There are a few scattered bruises across the chest and back.  The remainder of the examination shows no abnormalities.  Complete blood count results are as follows:  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d694_1afa_bc81_63236f77dfaf_MD0003_00 This patient's bone pain and pancytopenia are concerning for acute lymphoblastic leukemia (ALL), the most common leukemia in children. Bone pain is caused by leukemic infiltration of the bone marrow and typically affects the long bones (eg, femur, tibia). At night, the dull pain is often more noticeable, and during the day, children may limp or refuse to walk. The invasion of cancerous cells in the bone marrow also results in pancytopenia, with pallor (due to anemia) and bruising (due to thrombocytopenia); it also explains this patient's leukopenia (although ALL is classically associated with leukocytosis). In addition, fever is a common nonspecific finding, and hepatomegaly as well as splenomegaly can occur with extramedullary leukemic spread. Diagnosis is confirmed by >25% lymphoblasts on bone marrow biopsy. With treatment (ie, multidrug chemotherapy), prognosis is favorable in children, with a 5-year survival rate of >85%. (Choice B) Bone marrow failure due to aplastic anemia is characterized by pancytopenia. However, in contrast to the hypercellular bone marrow of ALL, the hypocellular bone marrow of aplastic anemia does not typically cause bone pain. In addition, hepatomegaly is uncommon with aplastic anemia. (Choice C) Immune thrombocytopenia is characterized by bruising and a low platelet count with normal red and white blood cells. (Choice D) Infectious mononucleosis due to Epstein-Barr virus causes fever, lymphadenopathy, and hepatosplenomegaly but not bone pain. (Choice E) Juvenile idiopathic arthritis is characterized by joint pain, swelling, and morning stiffness. Bony tenderness is not associated. (Choice F) Nonaccidental trauma can present with a vague history of bone pain (ie, fracture) and bruising. However, trauma would not depress cell counts. (Choice G) Osteomyelitis is a bone infection that can present with fever, leukocytosis, bone pain localized to the site of infection, and refusal to bear weight. This patient's pancytopenia, hepatomegaly, and diffuse bone pain (eg, affecting both tibias) make ALL more likely. Educational objective: Bone pain and pancytopenia in a child are concerning for acute lymphoblastic leukemia. Other characteristic findings include fever, pallor, bruising, and hepatosplenomegaly. References: Presentation and outcomes for children with bone marrow necrosis and acute lymphoblastic leukemia: a literature review. (http://www.ncbi.nlm.nih.gov/pubmed/21941136) Bone involvement at diagnosis as a predictive factor in children with acute lymphoblastic leukemia. (http://www.ncbi.nlm.nih.gov/pubmed/29097890)

A 5-Year-Old Girl Is Brought to the Office by Her