Here we report an unusual case of RT without any clinical, laboratory, or radiologic evidence suggestive of transformation other than cytopenia. Without any significant extramedullary involvement, RT presented in a leukemic phase that mimicked acute myeloid leukemia (AML). Importantly, despite the presence of a number of risk factors associated with a poor outcome, such as clonal relatedness, complex karyotype, expression of CD38 and ZAP70, thrombocytopenia, and multiple prior therapies, the patient responded well to ibrutinib monotherapy. This article is protected by copyright. All rights reserved.