A 14-year-old girl is evaluated for prolonged oozing after a dental extraction. Her screening labs show a prolonged Prothrombin Time (PT) and a normal Partial Thromboplastin Time (PTT). A deficiency of which of the following coagulation factors would best explain this isolated finding?
A 5-year-old child presents with fatigue and pallor. Physical exam reveals a spleen palpable 4 cm below the left costal margin. A complete blood count is ordered. The presence of which of the following best defines the condition of hypersplenism in this patient?
A 15-year-old male with a history of recurrent chylous effusions and bone lesions is diagnosed with a complex lymphatic anomaly. Genetic testing is performed to guide potential targeted therapy. An activating somatic variant in the NRAS gene would be most characteristic of which specific diagnosis?
A 7-year-old male with known hereditary spherocytosis presents for a routine check-up. He is asymptomatic with well-compensated hemolysis. His parents are concerned about the long-term risks and ask about the role of splenectomy. Which of the following is the most accurate statement regarding splenectomy in this patient’s condition?
A 17-year-old male with human immunodeficiency virus presents with generalized lymphadenopathy, fever, and night sweats. A lymph node biopsy confirms a diagnosis of multicentric Castleman disease. Testing for which of the following is crucial for sub-classification and guiding therapy in this patient?
A 2-week-old female infant, born to a mother with a history of immune thrombocytopenia who underwent splenectomy years ago, is found to have a platelet count of 25 × 10⁹/L. The mother’s current platelet count is normal. What is the most likely diagnosis?
A 2-year-old child presents with severe pallor and fatigue. Lab work reveals a normocytic anemia with a hemoglobin of 5.5 g/dL and marked reticulocytopenia. A bone marrow aspirate shows a selective reduction in red blood cell precursors. Which of the following findings would most strongly support a diagnosis of Diamond-Blackfan anemia (DBA) over transient erythroblastopenia of childhood (TEC)?
A 6-year-old boy presents with a new-onset, severe microcytic anemia that is refractory to oral iron therapy. He has no family history of anemia. His bone marrow examination reveals numerous ringed sideroblasts. A pathogenic variant in which gene is the most common cause of X-linked congenital sideroblastic anemia?
A 1-year-old male with severe hemophilia A, who has received 15 infusions of recombinant factor VIII concentrate, presents with a spontaneous hemarthrosis of the knee that is not responding to standard-dose factor replacement therapy. Which of the following factors is most strongly associated with an increased risk of inhibitor development?
An 8-year-old girl with transfusion-dependent β-thalassemia has been receiving regular red blood cell transfusions for years. Her physician is concerned about iron overload and wants to start chelation therapy. Which of the following is the most appropriate threshold to initiate iron chelation therapy?
