A 13-year-old boy presents to the emergency department with complaints of headache and visual changes. History reveals progressive dyspnea on exertion, generalized fatigue, and increased bruising. His labs are significant for a WBC of 350,000/mcL, of which 80% are reported to be blasts and appear to be myeloblasts without the presence of Auer rods. His hemoglobin is 7.2 g/dL, and his platelets are 18,000/mcL. A CT scan of the head shows a small intracerebral hemorrhage. His coags are normal. Which of the following is the most appropriate therapy?

Correct Answer: C

Rationale: The correct answer is C: Perform emergent leukapheresis plus hydroxyurea. In this scenario, the patient presents with symptoms suggestive of acute myeloid leukemia with hyperleukocytosis and intracerebral hemorrhage. The goal of emergent therapy is to rapidly reduce the high blast count to prevent further complications such as leukostasis and hemorrhage. Leukapheresis can provide immediate reduction in the blast count, while hydroxyurea can further decrease the WBC count. Starting induction chemotherapy immediately can lead to tumor lysis syndrome due to rapid cell destruction. Emergent cranial radiation is not the primary intervention for hyperleukocytosis. Performing leukapheresis alone without adjunctive therapy like hydroxyurea may not adequately control the blast count. Thus, the most appropriate initial therapy is emergent leukapheresis plus hydroxyurea to stabilize the patient before initiating induction chemotherapy.

Correct Answer: C

Rationale: The correct answer is C: Chronic myeloid leukemia (CML). This is a likely diagnosis due to the presence of fatigue, weight loss, night sweats, splenomegaly, anemia, thrombocytosis, and leukocytosis with an elevated white blood cell count. CML is characterized by the Philadelphia chromosome, resulting in the BCR-ABL fusion gene. This gene leads to uncontrolled proliferation of myeloid cells, causing the symptoms seen in this patient. Leukemoid reaction (A) is a reactive increase in white blood cells, usually in response to an infection. Acute lymphoblastic leukemia (B) typically presents with symptoms in children but is more commonly associated with lymphoblasts in the peripheral blood. JMML (D) is a rare myelodysplastic disorder in children characterized by monocytosis and a specific genetic mutation.

Correct Answer: D

Rationale: The correct next step is D: Obtain labs, including a CBC with platelet count and fibrinogen. This is the most appropriate action because the infant presents with an indurated and purpuric lesion with petechiae, suggesting a possible coagulation disorder. Labs can help assess for any underlying hematologic abnormalities. Choice A is incorrect because it is important to investigate further given the concerning presentation. Choice B is not the best next step as an ultrasound would not provide information on the hematologic status. Choice C is also not the best option as an MRI is not typically used to assess coagulation disorders.

Correct Answer: D

Rationale: The correct answer is D: Kruskal-Wallis test. Since the LOS data is not normally distributed, parametric tests like Student's t test and ANOVA are not appropriate. The Kruskal-Wallis test is a non-parametric test used to compare three or more independent groups when the data is not normally distributed. It ranks the LOS values across the three central line types and tests whether there are differences in medians. The Wilcoxon-Mann-Whitney test (choice C) is used for comparing two independent groups, not three. Therefore, it is not the appropriate test in this scenario.

Correct Answer: B

Rationale: Correct Answer: B Rationale: 1. Autologous hematopoietic stem cell transplantation should be used when it can provide a meaningful survival benefit over chemotherapy. 2. The most common cancers it is used for include neuroblastoma, responsive brain tumors in young children to avoid/minimize early radiation therapy, and relapsed lymphoma. 3. This choice aligns with the current guidelines and evidence-based practice in utilizing autologous stem cell transplantation for specific cancer types to improve outcomes. Summary of Other Choices: A: Incorrect. It is not necessary to use autologous stem cell transplantation solely for high-dose therapy. The listed cancers are not the most common indications for this procedure. C: Incorrect. The statement about the graft-versus-tumor effect is misleading, and the listed cancers are not the most common ones treated with autologous stem cell transplantation. D: Incorrect. Autologous stem cell transplantation is not used to shorten treatment or avoid extensive chemotherapy. The listed cancers