Spontaneous inversion of the left atrial appendage: a first autopsy case report and updated literature review

BACKGROUND: A mass in the left atrium commands immediate attention. Echocardiography reflexively points towards thrombus, vegetation, or tumour-the common culprits. Rarer, and easily overlooked, is a fourth possibility that has accumulated a quiet but instructive literature since the earliest days of open-heart surgery: inversion of the left atrial appendage. The spontaneous form, occurring outside any surgical context, is documented in fewer than ten cases worldwide. CASE PRESENTATION: We present the autopsy findings of a spontaneously inverted left atrial appendage in an 8-month-old male infant who had never undergone cardiac surgery. CONCLUSION: This case, placed alongside an updated review of the literature from 2020 to 2024, reinforces a simple but easily forgotten message: spontaneous left atrial appendage inversion can occur at any age, even in infants with no surgical history. A pressure gradient across the appendage wall, most often driven by pericardial effusion, appears to be the decisive pathophysiological trigger.