Retroperitoneal homunculus lesion in a newborn male

Abstract

Fetiform teratoma is a rare form of teratoma that resembles a malformed fetus due to highly organized differentiation. Most commonly seen arising from ovaries; however, we present a case of fetiform teratoma in the retroperitoneum in a male fetus. It is a unique case, as age, gender, and location point toward fetus-in-fetu where malignant transformation is highly unlikely. Distinction from fetus-in-fetu is necessitated due to malignant transformation in case of the presence of immature elements within.