Sacrococcygeal developmental abnormalities and tumors in children.

Lesions from the SC region of children examined histologically at the RAHC were: 1. Malformations almost always associated with spina bifida aperta or occulta: 183 myelomeningocele (MM), 32 meningocele (M), 35 lipoMM and lipoma, 19 dermoid cyst, six occult meningocele, two Pacinian hamartoma, one short filum, four hindgut cysts or sinuses, two tailgut cysts, and two epithelial heterotopia. 2. Neoplasms, usually without spina bifida: 56 teratomas (11 malignant), five ependymomas (two purely subcutaneous), and 14 miscellaneous primary malignancies, (most neuroblastoma and rhabdomyosarcoma). Distinction between MM with glial tissue and M without glial tissue is important as M had a much better prognosis, less than a third developing hydrocephalus, and 77% walking unaided. Of those with glial tissue, the eight without Arnold-Chiari malformation were myelocystocele associated with cloacal exstrophy (six), caudal regression syndrome (one), and microcephaly (one). Postsacral glial tissue without paraplegia may occur with a subcutaneous vestige of filum terminale, or with herniation of the nonfunctioning half of a diplomyelia. Of postsacral "lipomas" and dermoids, 70% had an intraspinal connection through an occult spina bifida. This posterior vertebral defect is easily overlooked as the arches normally may not ossify until after 6 years. Therefore, the pathologist receiving a postsacral specimen may wish to alert the clinician to the high incidence of late effects from an occult intraspinal component or tethering of the spinal cord. Transsacral hindgut herniations and cysts probably result from ectoendodermal adhesions. Presacral multicystic malformations with mixed squamous and mucus cell lining are probably tailgut remnants or anorectal duplications, and may be mistaken for dermoid or teratoma. In SC teratoma in infants, contrary to some reports on ovarian teratoma in adults, immature tissues do not indicate a worse prognosis. Malignancy is virtually confined to teratomas including a carcinomatous or "yolk sac" component. It is more common in predominantly presacral examples and rare before the age of 4 months. SC ependymoma differs from ependymoma elsewhere in that it may be primary outside the craniospinal cavity (presacral or postsacral), may have a myxopapillary pattern special to the region, and although low-grade and slow growing, is more likely to metastasize beyond the central nervous system. Postsacral examples arise from vestiges of the filum terminale which are normal in the subcutis there. Combinations of all these lesions occur with vertebral defects and with each other.(ABSTRACT TRUNCATED AT 400 WORDS)