A 51-year male patient presented with large skin masses of the chest wall that were pathologically proven to be chronic lymphocytic leukemia/small lymphocytic lymphoma(CLL/SLL) with Ki67:70%. The patient was treated with the time-limited Venetoclax/Obinutuzumab combination for 12 cycles and CLL/SLL including the skin component was set in complete remission.

We present a unique Richter's transformation case in CNS with identical to CLL clonal origin in a patient treated with Venetoclax. With our case we make implications on whether Venetoclax penetrates the blood-brain barrier and we address the debating issue of the appropriate Venetoclax dose in case of drug-drug interactions.