An Unexpected Occurrence of Malignancy in a Patient After a Fontan Operation.

An 18-year-old male with complex single ventricle physiology status post Fontan and Kawashima procedures who presented with progressive dyspnea was found to have severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rhinovirus, and a new retroperitoneal mass. Biopsy of the retroperitoneal mass revealed a mixed germ cell tumor with areas consistent with choriocarcinoma. Imaging showed metastatic disease, including to the lungs which ultimately led to worsening respiratory failure that required intubation and ultimately, death.