Intracardiac teratomas are rare primary tumours. We report the case of an infant prenatally diagnosed with an isolated multi-cystic mass developed in the right ventricle causing neonatal refractory ventricular arrhythmia. Despite rescue extracorporeal support and partial surgical resection, he died as almost all the previous reported perinatal intracardiac teratomas whatever the prenatal tolerance and the size of the tumour. The common poor outcome of fetal intracardiac teratomas should be known when counselling parents during pregnancy.

We consider a lifting of Joseph ideals for the minimal nilpotent orbit closure to the setting of affine Kac–Moody algebras and find new examples of affine vertex algebras whose associated varieties are minimal nilpotent orbit closures. As an application we obtain a new family of lisse ( $C_{2}$ -cofinite) $W$ -algebras that are not coming from admissible representations of affine Kac–Moody algebras.

For an arbitrary connected reductive group $G$ , we consider the motivic integral over the arc space of an arbitrary $ \mathbb{Q} $ -Gorenstein horospherical $G$ -variety ${X}_{\Sigma } $ associated with a colored fan $\Sigma $ and prove a formula for the stringy $E$ -function of ${X}_{\Sigma } $ which generalizes the one for toric varieties. We remark that, in contrast to toric varieties, the stringy $E$ -function of a Gorenstein horospherical variety ${X}_{\Sigma } $ may be not a polynomial if some cones in $\Sigma $ have nonempty sets of colors. Using the stringy $E$ -function, we can formulate and prove a new smoothness criterion for locally factorial horospherical varieties. We expect that this smoothness criterion holds for arbitrary spherical varieties.