Abstract

A total of 21 cases of sacrococcygeal teratomas is reviewed and analyzed histopathologically. They were 15 mature teratomas, one immature teratomas, and five endodermal sinus tumors. All but one neoplasm occurred in infants aged 3 years or younger and had visible masses at birth. Seventeen of these cases occurred in females. In mature teratomas, variable teratoid elements were observed and neuroglial tissue was particularly prominent among them. Also found were gastrointestinal mucosa, respiratory mucosa, pancreas, retinal tissue, and cartilage in order of frequency. Only one case of mature teratoma recurred and turned out to be endodermal sinus tumor with metastasis to the lungs. One immature teratoma showed undifferentiated neuroectodermal tissue in over half of the total area and the remaining portion consisted of mature neuroglial tissue and gastrointestinal mucosa. All endodermal sinus tumors were not combined with germinomatous or choriocarcinomatous elements. Three cases of endodermal sinus tumor contained mature teratoid components adjacent to the carcinomatous area. Based on the findings described above, we discussed some different histopathologic characteristics between the sacrococcygeal teratomas and gonadal teratomas, and speculated the possible origin of sacrococcygeal teratoma from the sequestrated protein in the proximal part of cloacal membrane. And this sequestration might be occurred during the process of cephalo-caudal folding in early embryonal period.