Sacrococcygeal teratoma in the perinatal period

Teratomas are formed when germ cell tumours arise from the embryonal compartment. The name is derived from the Greek word “teratos” which literally means “monster”. The ending “-oma” denotes a neoplasm.1 Sacrococcygeal teratoma is the most common congenital tumour in the neonate, reported in approximately 1/35 000 to 1/40 000 live births.2 Approximately 80% of affected infants are female—a 4:1 female to male preponderance.2 The first reported case was inscribed on a Chaldean cuneiform tablet dated approximately 2000 BC.3 In the modern era, the first large series of infants and children with sacrococcygeal teratomas was reported by Gross et al in 1951.4 Sacrococcygeal teratomas have tissues derived from ectoderm, mesoderm, and endoderm.2 Although their embryonic origin is still uncertain, they are believed to arise early in gestation (at around the late second or early third week) from the totipotential cells of Hensen's node (also called the primitive knot), a remnant of the primitive streak in the coccygeal region.5-7 The primitive streak appears as a linear thickening in the ectoderm at the caudal edge of the bilaminar embryonic disc. It usually diminishes in size, eventually disappearing after undergoing degenerative changes. As the mesoderm rapidly proliferates, the primitive streak comes to lie more and more caudally, where the remnant of Hensen's node descends to the tip or anterior surface of coccyx.5-7 Sacrococcygeal teratomas may be classified as benign (mature) and malignant or immature (composed of embryonic elements).8Mature teratomas are most common in neonates (68%) and older children (73%). Immature teratomas are cystic, whereas malignant tumours are solid. Over 50% of sacrococcygeal teratomas have calcification and ossification.8 Keslar et al reported that 69 (62%) of the 96 sacrococcygeal teratomas in their series were composed of both solid and cystic elements.8The cysts …