An 18-month-old boy is brought to the emergency department due to fatigue. Yesterday, his mother noticed that he was less active, and this morning, he did not want to get out of bed. The patient was born in Uganda, and the family recently moved to the United States. Temperature is 37 C (98.6 F), blood pressure is 74/40 mm Hg, pulse is 190/min, and respirations are 30/min. The patient appears tired. Eye examination shows equal and reactive pupils with bilateral scleral icterus. The oropharynx is clear, and the oral mucosa is pale. The neck is supple, and there are several 1-cm, anterior cervical lymph nodes. The lungs are clear bilaterally, and cardiac examination reveals a 2/6 systolic ejection murmur. Abdominal examination reveals tenderness on the left side. The spleen is palpable at the level of the umbilicus; the liver is not palpable. Bilateral distal pulses are weak. Which of the following would most likely establish this patient's diagnosis?

Question

An 18-month-old boy is brought to the emergency department due to fatigue.  Yesterday, his mother noticed that he was less active, and this morning, he did not want to get out of bed.  The patient was born in Uganda, and the family recently moved to the United States.  Temperature is 37 C (98.6 F), blood pressure is 74/40 mm Hg, pulse is 190/min, and respirations are 30/min.  The patient appears tired.  Eye examination shows equal and reactive pupils with bilateral scleral icterus.  The oropharynx is clear, and the oral mucosa is pale.  The neck is supple, and there are several 1-cm, anterior cervical lymph nodes.  The lungs are clear bilaterally, and cardiac examination reveals a 2/6 systolic ejection murmur.  Abdominal examination reveals tenderness on the left side.  The spleen is palpable at the level of the umbilicus; the liver is not palpable.  Bilateral distal pulses are weak.  Which of the following would most likely establish this patient's diagnosis?

Quizplus · Accepted Answer

11ec25c8_d6ac_fa6e_bc81_95426bda76f4_MD0003_00 This patient has splenomegaly with associated left-sided abdominal tenderness and signs of acute anemia (eg, fatigue, pale mucosa, flow murmur). This presentation most likely represents acute splenic sequestration crisis associated with sickle cell disease. Splenic sequestration is a potentially life-threatening complication of sickle cell disease that may be the presenting feature in some children. Because sickled red blood cells (RBCs) become trapped in the splenic sinuses, a large volume of blood pools in the spleen. The spleen rapidly enlarges (ie, tender splenomegaly), and hemoglobin drops acutely from baseline, resulting in fatigue, pallor, tachycardia, and even shock (eg, hypotension, weak pulses). Platelet counts are often low because of splenic sequestration, and reticulocyte production in the bone marrow increases in response to decreased circulating RBCs. Scleral icterus reflects underlying hemolysis. Hemoglobin electrophoresis showing the presence of hemoglobin S (HbS) (beta globin gene mutation) confirms the diagnosis of sickle cell disease. HbS polymerization in its deoxygenated state causing RBCs to form a sickle shape. Hemoglobin electrophoresis sickle shape (Choice A) Heart failure can cause shock and can occur with severe anemia. However, signs of fluid overload (eg, tachypnea, crackles) would be present, and hepatomegaly could occur. This patient's systolic flow murmur due to anemia does not require evaluation with echocardiography. (Choice B) Glucose-6-phosphate dehydrogenase deficiency causes acute hemolytic episodes after oxidative stress (eg, sulfa drugs, fava beans), not seen in this patient. Fatigue and jaundice occur, but dark urine due to hemoglobinuria would be expected, and splenomegaly is rare. (Choice C) Paroxysmal nocturnal hemoglobinuria (PNH), characterized by absent CD55 and CD59 on flow cytometry, is an acquired, complement-mediated hemolytic anemia. Thrombosis (eg, splenic vein, causing splenomegaly) can occur but is rare as a presenting manifestation. In addition, PNH is extremely rare in children, often causes dark urine, and is not typically associated with hypotension and shock. (Choice E) Lymph node biopsy is performed for suspected malignancy (eg, lymphoma). However, this patient's acute presentation, normal lymph nodes (eg, 1-cm anterior cervical lymph nodes), and signs of hemolysis (eg, scleral icterus) make lymphoma unlikely. (Choice F) Viral hepatitis can cause jaundice and scleral icterus, but hepatomegaly is generally present, and hypotension and splenomegaly with left-sided tenderness would be unusual. Educational objective: Splenic sequestration is a potentially life-threatening complication of sickle cell disease, an inherited red blood cell (RBC) disorder characterized by the presence of hemoglobin S on electrophoresis. RBCs become entrapped within the spleen, causing acute anemia and tender splenomegaly. References: Splenic sequestration crisis. (http://www.ncbi.nlm.nih.gov/pubmed/31985957)

An 18-Month-Old Boy Is Brought to the Emergency Department Due