Differential Diagnosis for an 8-year-old Female with Fatigue, Pallor, and Unexplained Bruises

Single Most Likely Diagnosis

• Acute Myeloid Leukemia (AML): The presence of 53% blasts in the peripheral blood with Auer rods, a high WBC count, and a decreased platelet count strongly suggests AML. Auer rods are particularly indicative of myeloid lineage leukemia.

Other Likely Diagnoses

• Acute Lymphoblastic Leukemia (ALL): Although the presence of Auer rods points more towards AML, ALL cannot be ruled out without further testing, such as immunophenotyping. However, the manual differential showing a predominance of myeloid lineage cells (promyelocytes, myelocytes, metamyelocytes) makes ALL less likely.
• Myelodysplastic Syndrome (MDS): This could be considered given the cytopenias (anemia suggested by pallor, thrombocytopenia) and the presence of blasts, but the high percentage of blasts and the specific findings of Auer rods make AML more likely.

Do Not Miss Diagnoses

• Severe Aplastic Anemia: Although the bone marrow would likely be hypocellular in aplastic anemia, which contrasts with the expected hypercellularity in AML, it's crucial to consider due to the potential for similar presenting symptoms (fatigue, pallor, bruising). However, the presence of a high WBC count with blasts makes this less likely.
• Infection or Sepsis: Infections can cause significant changes in the CBC, including a high WBC count, but the presence of blasts and Auer rods is not typical for infection alone.

Rare Diagnoses

• Myeloproliferative Neoplasms (MPN): These are rare in children and would not typically present with such a high percentage of blasts or Auer rods.
• Leukemia Cutis or Other Extramedullary Hematopoietic Tumors: These could present with similar symptoms but are less common and would require specific diagnostic tests for confirmation.

Chromosomal Translocations Least Likely to be Found

Given the clinical presentation and laboratory findings suggestive of AML, the chromosomal translocations least likely to be found would be those more commonly associated with other types of leukemia or lymphoma:

• t(8;14): This translocation is commonly associated with Burkitt lymphoma, a type of non-Hodgkin lymphoma.
• t(9;11), t(8;21), and t(16;16) are all associated with specific subtypes of AML, making them less likely to be the "least likely" given the context of AML suggested by the presence of Auer rods and the blast percentage. However, among these, t(8;14) is the least associated with AML and more specifically linked to lymphoid malignancies, making it the correct answer in the context of the question asking for the least likely translocation in AML.