Nokea
You examine a 10-year-old boy with severe aplastic anemia. He has no dysmorphic features and is at the 50th percentile for height and weight. Family history includes a sister with aplastic anemia unresponsive to anti-human thymocyte globulin (ATG) and cyclosporine who died early in the course of an unrelated donor hematopoietic stem cell transplant complicated by severe mucositis and transplant-related organ toxicities. There are no other siblings. A cousin died of acute myeloid leukemia at age 5 years. A peripheral blood sample test for Fanconi anemia is negative with no increased chromosomal breaks in response to diepoxylbutane or mitomycin C. Which of the following is the most important next step in management?
Correct Answer: D
Rationale: The correct answer is D: Send a skin fibroblast culture for Fanconi anemia testing. This is the most important next step in management because the patient's history, including a family member with aplastic anemia and a cousin with leukemia, raises suspicion for a genetic disorder like Fanconi anemia. Testing skin fibroblasts for Fanconi anemia can help confirm or rule out this diagnosis. Administering ATG and cyclosporine (choice A) may not be effective if the underlying cause is a genetic disorder. Searching for a donor for matched unrelated transplant (choice B) is premature without confirming the diagnosis. Sending a bone marrow aspirate for Fanconi anemia testing (choice C) may not yield accurate results as the peripheral blood sample test was negative, making skin fibroblast culture the preferred choice.