case_images: PMC10756059_01
case_images: (A) At initial diagnosis, bone marrow aspiration revealed large myeloblasts with subtle nuclear irregularities and scattered cytoplasmic granules (HE, 1000x). (B) Chromosomal karyotype: 45, X, -Y, t (8;21) (q22; q22).
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case_images: Bone marrow aspiration showed 38.5% blast cells ( Figure 1A ). A cytogenetic analysis showed the presence of t (8;21) ( Figure 1B ), which resulted in the AML1/ETO fusion gene detected by PCR analysis.
case_images: MRI revealed CNS involvement and extramedullary infiltration. (A-C) Diffuse hypointensity on T1WI and hyperintensity on T2-FlAIR of skull diploe (arrows), indicated leukocyte infiltration. (D) Soft tissue mass (arrow) adjacent to the left 9th-10th thoracic vertebrae on coronal T1WI+C. (E, F) Significant shrinkage of the soft tissue mass (arrow) of the thoracic vertebrae after localized radiotherapy.
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case_images: FLAIR and DWI sequences, indicating potential skull bone involvement ( Figures 2A-C ). Following two cycles of "3 + 7" chemotherapy with idarubicin and cytarabine, bone marrow blast count decreased to 4.0%; then a lumbar puncture was performed, revealing a CSF pressure of 220 mmH2O, with normal CSF analysis results. However, in April 2021, a high-resolution CT of the chest revealed a new soft tissue mass adjacent to his thoracic vertebrae, most likely an extramedullary lesion ( Figure 2D ). The involved site radiation therapy (ISRT) effectively resolved the mass ( Figures 2E, F ).
case_images: A timeline of the patient's clinical courses.
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case_images: The timeline of this case was summarized in  Figure 3 .