A fatal posterior-fossa chloroma masquerading as tuberculous meningitis after peripartum BCR-ABL1 inhibitor cessation - a case report.

Intracranial myeloid sarcoma complicating chronic myeloid leukemia (CML) is exceptional; when its cerebrospinal-fluid profile simultaneously mimics tuberculous meningitis (TBM), the diagnostic trap becomes fatal. A 27-year-old postpartum woman with Ph⁺ CML, initially presenting in B-cell acute lymphoblastic leukemia lymphoid blast crisis, developed rapidly progressive posterior-fossa syndrome following peripartum tyrosine kinase inhibitor (TKI) discontinuation. CSF revealed lymphocyte-predominant pleocytosis, hypoglycorrhachia, hyperproteinorachia, and adenosine deaminase 33 U/L, with negative CBNAAT, malignant cytology, and flow cytometry; BCR-ABL1 P210 registered an International Scale of 49.196%. Contrast-enhanced MRI demonstrated a dural-based, homogeneously enhancing, diffusion-restricting cerebellopontine mass with pachymeningeal involvement, consistent with granulocytic sarcoma. Death from tonsillar herniation occurred within one week, before tissue confirmation. Three imperatives emerge: CSF adenosine deaminase elevation lacks specificity for TBM in hematological malignancy; Ph⁺ CML can undergo myeloid CNS relapse following peripartum TKI cessation; and a posterior-fossa dural mass in leukemia demands urgent tissue diagnosis.