Atypical presentation of sacrococcygeal yolk sac tumor in infant: beware of the injuries of the gluteal region.

Malignant sacrococcygeal yolk sac tumor is a rare extra-gonadal germ cell tumor of infancy and childhood. We report the case of a 14-month-old white female infant with a rapidly growing supra-gluteal mass at first misdiagnosed as hemangioma after a clinical assessment. The lesion was then classified as extra-gonadal yolk sac tumor due to alarming ultrasound features, later confirmed at MRI and pathology. This report remarks the need of a rigorous methodology in the ultrasound exploration of the gluteal region.