Hematology-oncology (HO) fellows receive limited instruction in the process of establishing a diagnosis for hematologic neoplasms, and learning neoplastic hematology often occurs in limited encounters. In the current study, we developed a web-based interactive pathology tutorial in neoplastic hematologic disorders for HO fellows to work up simulated cases and establish the diagnosis. An online system (“Pathology Playground”) was utilized to load case materials including microscopic images and ancillary studies. Twelve high-yield simulated cases of common leukemias and lymphoma were included. At the beginning of each case, trainees review the clinical history and slide images, and then, they are given the option to request additional pathology work-up. Based on the results, they can enter their diagnostic impression. If the diagnosis is correct, the user is shown a short educational presentation. If the diagnosis is not correct, the user gets notified by the message “Incorrect.” The tutorial was integrated in the educational curriculum of our HO fellowship program, and bimonthly teaching sessions were held to review two cases each time. During the sessions, trainees request ancillary studies to complete the diagnostic work-up using the software and interpret the findings. As the case is being worked up by the trainee, the hematopathologists and HO fellowship program director discuss the findings, the appropriate work-up tools, and the implications on management. All of our six HO fellows attended the sessions, and a survey from the trainees showed high ease of use of the system and they viewed it as a very useful educational tool. A pre-test and post-test were administered for one of the sessions, and the result showed improvement in the average from 62 to 73%. Expanding the use of this online interactive tutorial and incorporating additional cases would enhance its value as a learning resource.