Fetus-in-fetu or well-differentiated teratoma- a continued controversy.

Fetus in fetu is an uncommon anomaly in pediatric age group. There have been controversies regarding its differentiation from well differentiated teratoma. While presence of axial skeleton has been considered mandatory for diagnosis, there are many reports of fetus in fetu without any vertebral column. It has been suggested that the two entities form a spectrum of lesions depending upon the timing of embryological insult. The present case is another example of a lesion that fits in this spectrum of interesting lesion.