Lentoids within sacrococcygeal teratoma: origin by transdifferentiation?

Within a teratoma removed surgically from the sacrococcygeal region of a female newborn, clusters of lens-like cells (lentoids) surrounded by the immature tissue of the neural retina were revealed by routine histologic analysis. Comparison of the cytologic and microtopographic characteristics of lentoids that develop in experimental embryo-derived teratomas suggests that the lentoids within the sacrococcygeal teratoma originate by transdifferentiation (cell-type conversion, metaplasia) of cells of the immature neural retina or the pigmented retinal epithelium. The embryonic origin of sacrococcygeal teratomas is discussed in the context of complex morphogenetic features at the posterior end of the early embryo.