Maia, L.M.E.P. and Maia, F.P. 2026. Inferior Vena Cava Mesenchymal Tumor with Intracardiac Extension Mimicking an Atrial Myxoma in a Young Adult: A Case Report. Brazilian Journal of Case Reports. 6, 1 (Jan. 2026), bjcr153. DOI:https://doi.org/10.52600/2763-583X.bjcr.2026.6.1.bjcr153.