Monoclonal B Lymphocytosis (MBL) is considered the pre-malignant state of chronic lymphocytic leukemia (CLL) and atypical chronic lymphocytic leukemia (aCLL). Both entities are rarely found in association with other hematological tumors; still, they naturally tend to progress to more aggressive lymphomas. This manuscript reports the case of an 81-year-old Caucasian male under follow up for MBL who presented to the Emergency Department with severe anemia and thrombocytopenia. A complete diagnostic workup revealed the simultaneous presence of atypical CLL and B-acute lymphoblastic leukemia, with minimal blast presence in peripheral blood.