RT Journal A1 Gwinn JL, Lee FA T1 RAdiological case of the month JF American Journal of Diseases of Children JO American Journal of Diseases of Children YR 1969 FD March 1 VO 117 IS 3 SP 319 OP 320 DO 10.1001/archpedi.1969.02100030321012 UL http://dx.doi.org/10.1001/archpedi.1969.02100030321012 AB CLINICAL HISTORY.—This 1-day-old girl was transferred to Childrens Hospital, Los Angeles, with a large mass in the buttock. The mass was noted at birth. The mother's pregnancy and delivery were uncomplicated.Physical Examination.—The infant was alert, active, and in no distress. A 5 × 5 cm firm, purplish mass was palpable in the buttock. By rectal examination, the mass seemed to extend into the pelvis, posterior to the rectum. A firm mass was also palpable in the lower abdomen. The remainder of the examination was not remarkable. Radiographic studies were done (Fig 1-3).Denouement and Discussion  Hydrometrocolpos and Sacrococcygeal Teratoma  If an infant has one congenital anomaly, incidence of a second anomaly becomes very high.The presacral area is the most common site of teratomas in infancy. They usually present as a mass in the buttocks and extend into the presacral area (Fig 1 left). The radiograph may