There are a variety of disorders among tumors in the lunibosacral area in neonates. We discuss here on the problems of diagnosis and treatment of such tumors, by our experience with 84 cases at Chiba University in the past 12 years. Most of 38 open myelonienmgoceles were easily diagnosed. They were mostly operated within 24 hours after birth. There were 6 cases with very small neural plaque on the midline, which were not referred early and were not operated on as emergency cases. In these, more post-operative troubles were observed. There were 34 cases of closed myelomeningcele. They were subcutaneous abnormalities. Fifteen cases were with lipomeningmyelocele, four with small meningeal sac as the main lesion, 5 with abnormal skin tumor, 5 with cicatrical epithelium and 5 with dermal dimple. The lesion was located between L-4 and S-2 of the vertebral level. No hydrocephalus was observed in these cases. Neurogenic bladder was observed in only 4 cases with lipomyelomeningocele and a dermal dimple in one in the post-operative follow-up course. We usually operate on these patients during infancy, between one and 8 months of age, before any neurological disorders are found by physical examinations. We believe that this condition must be operated on before the irreversible mal-effcct of the tethered cord appears. There were 3 cases of sacral abscess. They were incised and drained successfully. All of them were caused by Staphylococcus aureus. Real etiology of this was not known. Eleven cases of sacrococcygeal teratoma were experienced during the same period. Some of them were very difficult in defferntiation from closed myelomeningocele. Sacrococcygeal teratoma must be operated on during the neonatal period for prevention of malignant transformation, while closed myelomeningocele need not be operated on so early. The points of differentiation are the vertebral level to be under S-3, anterior shift of the anus and compression defect of the posterior wall of the rectum demonstrated in barium enema, which are seen in sacrococcygeal teratoma. Also we discussed on the confused terminology of spina bifida. We prefer to use the "open" and "closed" meningomyelocele and mcningocele according to anatomical evaluations.
