[An endodermal sinus tumor (yolk sac tumor) of the anterior mediastinum].

An own case of a primary mediastinal endodermal sinus tumour (yolk sac tumour) is presented that was transformed under therapy into an AFP-negative process and occurred combined with an arcus aortae dexter. This is followed by a description of the clinical and diagnostic patterns of signs and symptoms and of the treatment of this very rare dysontogenetic tumour.