Differential Diagnosis
The patient's presentation with 25% circulating blasts, negative cytochemical stains, and the presence of myeloid antigens on flow cytometry immunophenotyping guides the differential diagnosis. Here are the considerations:
Single most likely diagnosis
- D. acute myeloid leukemia (AML): The presence of 25% circulating blasts is diagnostic for acute leukemia. The lack of Auer rods does not rule out AML, as they are not present in all cases. The expression of myeloid antigens on flow cytometry strongly supports a myeloid lineage, making AML the most likely diagnosis.
Other Likely diagnoses
- None: Given the information, the other options are less likely. However, it's essential to consider the broad differential of acute leukemia, but the specifics provided point more directly to AML.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- C. chronic myeloid leukemia (CML) in blast crisis: Although CML is typically characterized by a much higher leukocyte count with a predominance of mature myeloid cells and the presence of the BCR-ABL1 fusion gene, transformation into blast crisis can present similarly to AML. It's crucial to differentiate because the treatment approaches can differ significantly.
- A. acute lymphoblastic leukemia (ALL): Although the presence of myeloid antigens points towards AML, some cases of ALL can express myeloid antigens (mixed phenotype acute leukemia). ALL treatment is different from AML, making accurate diagnosis critical.
Rare diagnoses
- Mixed Phenotype Acute Leukemia (MPAL): This is a rare type of leukemia that expresses both myeloid and lymphoid markers. Given the presence of myeloid antigens, this could be considered, but it would require additional lymphoid markers to be expressed.
- Other rare myeloid neoplasms: Depending on additional clinical and laboratory features, other myeloid neoplasms could be considered, but they are less likely given the provided information.