Background: Ibrutinib, a Bruton’s tyrosine kinase inhibitor (BTKi), has revolutionized the treatment of Chronic Lymphocytic Leukemia (CLL), yet hepatotoxicity remains a rare and poorly characterized adverse event. Case Presentation: We report the case of a 54-year-old man with progressive CLL and radiologically confirmed hepatic involvement who developed acute hepatocellular injury during ibrutinib monotherapy. Baseline liver tests showed mild abnormalities attributed to hepatic steatosis and leukemic infiltration. After approximately 10–12 weeks of ibrutinib (420 mg/day), transaminases markedly increased (ALT 660 U/L, AST 326 U/L), while bilirubin and synthetic function remained normal. Viral, autoimmune, and obstructive causes were excluded. Stepwise dose reductions to 140 mg/day provided limited benefit. The addition of prednisone (50 mg/day) led to rapid biochemical improvement. Ibrutinib was successfully re-escalated to 280 mg/day alongside venetoclax initiation, maintaining disease control without recurrence of liver injury. Discussion: The temporal relationship, exclusion of alternative causes, and corticosteroid responsiveness suggest an ibrutinib-induced liver injury, possibly exacerbated by pre-existing hepatic steatosis and leukemic infiltration. Conclusions: This case underscores the multifactorial pathogenesis of BTKi-related hepatotoxicity and highlights the potential role of corticosteroids in management. Prompt recognition, stepwise dose adjustment, and corticosteroid therapy may enable continued treatment and sustained disease control in selected patients.

The FLT3-ITD mutation is a critical prognostic marker in acute myeloid leukemia (AML) and recent clinical trials demonstrate that FLT3-based measurable residual disease (MRD) is both prognostic and predictive, guiding therapeutic interventions in intensive and post-transplant settings. Conventional detection methods lack the sensitivity required for effective MRD monitoring. We developed a patient-specific droplet digital PCR (ddPCR) approach achieving analytical sensitivity of 10⁻⁵ (0.001%) for FLT3-ITD quantification. In our cohort, ddPCR enabled longitudinal monitoring of clonal dynamics, allowing the detection of re-emerging FLT3-ITD clones months before hematologic relapse and earlier than standard capillary electrophoresis. Notably, 25% of patients who relapsed as FLT3-ITD positive despite being classified as FLT3-negative at diagnosis harbored detectable microclones when retrospectively analyzed by ddPCR, suggesting that FLT3-ITD-positive relapse frequently originates from pre-existing subclones below conventional detection thresholds. These findings challenge current diagnostic classification and may influence risk stratification and treatment decisions, particularly regarding FLT3 inhibitor eligibility. While ddPCR is limited to tracking known dominant clones, it represents a practical, cost-effective solution for high-sensitivity MRD surveillance. In the era of targeted FLT3 therapies, integrating sensitive molecular monitoring into routine AML management may enable timely therapeutic adjustments and improve patient outcomes.