Not Your Usual Tamponade: A Rare Manifestation of Cardiac Myeloid Sarcoma

Description of Clinical Presentation: A 68-year-old male with a history of myelodysplastic syndrome status post allogeneic hematopoietic stem cell transplant presented with 1-2 months of progressive exertional dyspnea. He was in acute hypoxic respiratory failure, requiring supplemental oxygen, though hemodynamically stable. Physical exam demonstrated an irregular rhythm with diminished heart sounds. Electrocardiogram demonstrated low voltage atrial fibrillation. An initial computed tomography angiography (CTA) to assess pulmonary or embolic etiologies revealed a large pericardial effusion and left-sided pleural effusion, leading to additional diagnostic imaging modalities (Figures A and B).

Diagnostic Techniques and Their Most Important Findings: A subsequent transthoracic echocardiogram (TTE) demonstrated a right atrial free wall adherent mass measuring 2.0 cm x 1.4 cm and circumferential pericardial effusion with tamponade physiology (Figure C). Emergent pericardial window procedure was pursued revealing hemorrhagic fluid. The differential diagnosis for pericardial effusion included acute decompensated heart failure, graft versus host disease, infectious etiologies, and malignancy. Thoracentesis of the pleural effusion with cytology analysis showed CD34 and CD117 positive cells, raising concern for myeloid sarcoma. Additional multimodality imaging was pursued. Cardiac magnetic resonance image (MRI) revealed an infiltrative soft tissue mass involving the right atrium, extending from the right ventricular free wall to the right atrioventricular groove (25.3 mm) with encasement and narrowing of the SVC and IVC. Cardiac MRI also demonstrated restricted right atrial and basal right ventricular motion due to soft tissue encasement of the chambers. These findings guided the subsequent indication for intracardiac biopsy under transesophageal echocardiogram guidance via the transvenous liver biopsy system, a novel use for this device. Histopathology and molecular analysis of the mass confirmed the ultimate diagnosis of isolated, extramedullary cardiac myeloid sarcoma (MS).

Learning Points from this Case: Cardiac MS is a rare hematologic malignancy characterized by myeloid blasts invading cardiac tissue. It is treated using radiation and targeted chemotherapies, often with high mortality, as was the ultimate case for this patient. Limited published clinical reports about this uncommon condition warrant high index of clinical suspicion. Although multimodality imaging can identify characteristics of a malignant intracardiac mass, tissue biopsy remains the gold standard for diagnosis and characterization to guide therapy and prognosis. Cardiac MS is a rare primary cardiac malignancy with no established treatment guidelines, but accurate tissue diagnosis can help tailor therapy.

Four-chamber multiplanar reconstruction from cardiac CT angiogram showing large intracardiac mass (asterisks) involving right atrium (RA).
Right ventricular inflow-outflow view demonstrating the same mass (asterisks) with superior vena cava (SVC) stenosis.
Transthoracic echocardiogram in the apical four-chamber view showing the intracardiac mass (asterisk) and a complex pericardial effusion (arrows).