A 4-year-old boy is brought to the emergency department by his father for increasing fatigue. Three weeks ago, the patient developed a fever and congestion. The upper respiratory symptoms resolved, but the fever has persisted and he has also developed poor appetite and some weight loss. The patient has been less active and is refusing to walk. He has no chronic medical conditions. The patient's family emigrated from Kenya 2 years ago. Temperature is 39.4 C (102.9 F), blood pressure is 100/70 mm Hg, and pulse is 140/min. Height and weight are at the 80th percentile. The oropharynx is clear, and the conjunctivae are pale. Enlarged, nontender lymph nodes are palpable in the cervical, axillary, and inguinal regions. Lungs are clear to auscultation, but the spleen is enlarged. Deep palpation along the middle of the bilateral thighs elicits tenderness. Multiple petechiae are seen. Laboratory results are as follows: Chest x-ray is normal. Which of the following would most likely confirm the diagnosis?

Question

A 4-year-old boy is brought to the emergency department by his father for increasing fatigue.  Three weeks ago, the patient developed a fever and congestion.  The upper respiratory symptoms resolved, but the fever has persisted and he has also developed poor appetite and some weight loss.  The patient has been less active and is refusing to walk.  He has no chronic medical conditions.  The patient's family emigrated from Kenya 2 years ago.  Temperature is 39.4 C (102.9 F), blood pressure is 100/70 mm Hg, and pulse is 140/min.  Height and weight are at the 80th percentile.  The oropharynx is clear, and the conjunctivae are pale.  Enlarged, nontender lymph nodes are palpable in the cervical, axillary, and inguinal regions.  Lungs are clear to auscultation, but the spleen is enlarged.  Deep palpation along the middle of the bilateral thighs elicits tenderness.  Multiple petechiae are seen.  Laboratory results are as follows:  Chest x-ray is normal.  Which of the following would most likely confirm the diagnosis?

Quizplus · Accepted Answer

11ec25c8_d693_3098_bc81_717acdc35694_MD0003_00 This child has pancytopenia, which is typically caused by increased cell destruction or impaired cell production. In this case, the patient's bone pain and diffuse lymphadenopathy are concerning for acute lymphoblastic leukemia (ALL). In ALL, uncontrolled growth of malignant cells in the bone marrow results in impaired production of normal cell lines (ie, bone marrow failure). Although initial symptoms of ALL are often nonspecific (eg, fever, poor appetite, weight loss), physical examination frequently reveals pallor and bruising/petechiae due to anemia and thrombocytopenia, respectively. Leukopenia with recurrent infections can occur; however, leukocytosis often is seen due to spread of lymphoblasts from the bone marrow to the periphery. As leukemic cells proliferate and expand the bone marrow, many children develop bone pain (eg, pain with deep palpation, refusal to walk) affecting the long bones (eg, femur, tibia). In addition, lymphadenopathy and hepatosplenomegaly can result from extramedullary leukemic spread. Bone marrow evaluation is diagnostic; in normal marrow, blasts (immature cells) comprise a small percentage of cells, whereas diagnosis of ALL is confirmed by abnormally increased lymphoblasts (eg, >20%) on bone marrow aspirate. blasts (Choice A) Antinuclear antibodies screen for systemic lupus erythematosus, a rare diagnosis in young children that may cause pancytopenia in addition to fever, lymphadenopathy, and splenomegaly. However, swelling/pain of joints is typical, and this patient's midshaft tenderness of a long bone makes this diagnosis less likely. (Choice C) Infectious mononucleosis caused by Epstein-Barr virus (EBV) can present with prolonged fever and fatigue as well as diffuse lymphadenopathy and splenomegaly; pancytopenia can occur. In contrast to this case, lymph nodes are typically tender, and bone pain/refusal to walk would not be seen. (Choice D) Hemoglobin electrophoresis is diagnostic of sickle cell disease, which often causes splenomegaly in young children and can present with fever and bone pain (ie, vasoocclusive pain crisis) in the setting of infection (eg, parvovirus). Although parvovirus can cause aplastic crisis in such patients, this complication is characterized by severe anemia, not lymphopenia or thrombocytopenia. Moreover, diffuse lymphadenopathy is not seen. (Choice E) Fever, fatigue, lymphadenopathy, splenomegaly, and pancytopenia can be seen in HIV. However, transmission in young children typically occurs perinatally with symptoms (eg, failure to thrive, opportunistic infections) beginning in infancy; acute symptom onset in an otherwise healthy child at age 4 is unlikely. Educational objective: Acute lymphoblastic leukemia classically presents with signs of pancytopenia (eg, pallor, bruising, petechiae), bone pain, and hepatosplenomegaly in children. Diagnosis is confirmed by >20% lymphoblasts in the bone marrow. References: Acute lymphoblastic leukaemia. (http://www.ncbi.nlm.nih.gov/pubmed/23523389)

A 4-Year-Old Boy Is Brought to the Emergency Department by His