T-lymphoblastic lymphoma presenting as pericardial tamponade: A rare initial manifestation of an aggressive malignancy

Abstract Background: T-lymphoblastic leukemia/lymphoma (T-ALL/LBL) is a rare, aggressive neoplasm of precursor T-cells, typically affecting children and young adults. It usually presents with mediastinal masses, lymphadenopathy, or leukemic features. Initial presentation with pericardial tamponade is exceedingly rare and diagnostically challenging. Additionally, prompt recognition and intervention are essential in such cases Case Presentation: We describe a previously healthy 35-year-old male who presented with progressive dyspnea, dry cough, fever, night sweats, and unintentional weight loss. Upon presentation, patient was in respiratory distress, and physical examination revealed tachycardia, jugular venous distention, and muffled heart sounds. Chest X-ray showed a large anterior mediastinal mass and bilateral pleural effusions. Transthoracic echocardiography confirmed tamponade physiology. Emergent pericardiocentesis yielded 200 mL of fluid, with cytology suggestive of a lymphoid malignancy. Further workup, including contrast-enhanced CT and PET/CT, revealed a large necrotic anterior mediastinal mass encasing the great vessels. CT-guided biopsy and immunohistochemistry confirmed T-ALL/LBL (CD3+, CD10+, TdT+). Bone marrow aspiration showed no leukemic infiltration, consistent with T-LBL. The patient was initiated on induction chemotherapy (dexamethasone, daunorubicin, vincristine, peg-asparaginase) and discharged in stable condition. Conclusion: This case underscores the importance of including hematologic malignancies in the differential diagnosis of unexplained pericardial effusion and tamponade. Prompt imaging, cytology, and histopathologic confirmation are essential. Early Multidisciplinary coordination is critical to initiate timely and life-saving therapy in such rare and aggressive presentations.