Pericardial effusion, a clinical condition characterized by an abnormal accumulation of fluid in the pericardial cavity, has multiple etiological factors. One of the prominent causes is malignant effusion. The patient is a 69-year-old female with a past medical history of Crohn's disease, melanoma status post-resection, and osteoarthritis. She presented with complaints of abdominal discomfort, shortness of breath on exertion, and lower extremity swelling for the past 2-3 days. She was recently discharged four days before this visit after being treated for a viral infection. A physical examination was significant for tachycardia, muffled heart sounds, abdominal distention, and bilateral lower extremity swelling. Labs were in the normal range except for elevated liver enzymes and sodium of 130 mmol/L. A chest X-ray revealed a small bilateral effusion; a bedside echocardiogram showed an ejection fraction greater than 70% and a large pericardial effusion >2 cm, consistent with cardiac tamponade. Emergent pericardiocentesis was performed with the drainage of 250 milliliters of hemorrhagic fluid, which was sent for diagnostic studies. Post-procedure echo on the next day showed an EF of 35-40% and no recurrent pericardial effusion. The workup for connective tissue disease was negative except for elevated antinuclear antibodies (ANA). CT of the abdomen and pelvis revealed gastric wall thickening with no solid organ mass. Her pericardial fluid studies were consistent with exudative etiology and positive for atypical lymphoid cells, leading to the diagnosis of diffuse large B-cell lymphoma. Diffuse large B-cell lymphoma is the most common type of non-Hodgkin lymphoma. Malignant pericardial effusion is common due to solid organ malignancy; however, it is rare with diffuse large B cell lymphoma (DLBCL). We present an intriguing case where pericardial effusion was the precursor to the eventual diagnosis of DLBCL, highlighting the complexity and diverse manifestations of this lymphoma subtype.