[Omphalosite monster (acardius acephalus). Apropos of a case].

The omphalosite monster is acardiac (deprived of heart) and his survival is only possible through intrauterine life because of the umbilical vascular connections with his healthy monochorionic twin brother who takes in charge the circulation of both. We report one typical case of the acephalic variety in which all structures derived from the fetal cephalic fold were absent. Its only eventual clinical interest is limited to the prenatal radiological diagnosis and the neonatal onset of congestive heart failure in the healthy twin, a fact which must be known in order to establish an early treatment. On this occasion, we briefly review the current knowledge about this very rare form of monstrosity.