Hairy Cell Leukemia: A Differential Diagnosis of Hepatitis B-Associated Aplastic Anemia and Syphilis

Aplastic anemia occurs with an incidence of 2-5: 1 million people worldwide. However, the frequency of newly diagnosed cases of bone marrow aplasia is greater, and some of these patients present to emergency departments initially. <b>Description of Case:</b> We present the case of a middle-aged man with pancytopenia. In this case, aplastic anemia associated with hepatitis B and syphilis was only the initial diagnosis. An indolent hematologic malignancy-hairy cell leukemia-was diagnosed as the real cause of the bone marrow failure in a clinic of hematology. <b>Conclusions:</b> This clinical case allows us to make a conclusion, albeit not definitively, about the contribution of hepatitis B and syphilis to the clinical manifestation of hairy cell leukemia. A detailed and consistent diagnostic plan is also required in patients presenting with pancytopenia. Failure to diagnose a hepatitis B infection in a patient with malignant hematologic disease would lead to fatal therapeutic errors.