Hematological malignancies are protean in their presentations. Primary cardiac tumors are exceedingly rare, and primary cardiac leuke mia presenting as an isolated mass is even rarer. Here, we present a case of a young man who presented with a history of fever and short ness of breath for the past month. His examination revealed signs of right sided heart failure. On workup he was found to have a mass in the heart on computed tomography scan of the chest, his transthoracic echocardiography showed an isolated right atrioventricular groove mass. Surgical biopsy confirmed it to be an extremely rare presentation of pre‑B‑cell acute lymphoblastic leukemia. The patient underwent surgical excision of the lesion. In the further course, the patient developed bone marrow leukemic involvement, confirmed by bone marrow biopsy and died of overwhelming sepsis secondary to pancytopenia. This case highlights that hematological malignancies can present as cardiac masses and should be considered during workup of patients presenting with chronic fever and right sided heart failure