Pericardial cysts are rare mediastinal abnormalities, generally benign, discovered most often incidentally in the course of diagnostic investigations involving the cardiac profile. They have an incidence of 1 case in 100 000 and are mostly located at the right cardiophrenic angle. Spontaneous resolution of cysts is even rarer. We describe an intricate case report in which the cyst was discovered incidentally and was no longer detected at cardiac magnetic resonance performed 7 years after the first diagnosis. The presence of an asymptomatic pericardial cyst should be regularly followed up over time for the potential risks of complications related to its growth but also because over time, although rarely, it may no longer be detected as in the case presented.