Sacrococcygeal teratoma showing organoid differentiation: report of a case.

We present the case of a neonate with a sacrococcygeal teratoma showing organoid differentiation. A 5-day-old baby girl was transferred to our hospital with a large sacrococcygeal mass. Ultrasonography revealed a few well-limited fluid-filled lesions, indicating that the teratoma had cystic components. During surgery, a sac containing 30cm of small bowel loops was found in the tumor. The bowel segment was supplied by a mesentery-like structure originating from teratoid tissue. Histopathological examination verified a benign mature teratoma with fully developed small bowel loops. The tumor was defined as a sacrococcygeal fetiform teratoma. The terminological, structural, and clinical aspects of this unusual tumor are discussed, with a review of the English literature.