Terminal Myelocystocele and Sacrococcygeal Teratoma: A Comparison of Fetal Ultrasound Presentation and Perinatal Risk

Abstract

SUMMARY:This case exemplifies the difficulty in differentiating cystic sacrococcygeal teratoma and terminal myelocystocele. Fetal sonography presentation and perinatal risks of sacrococcygeal teratoma and terminal myelocystocele are compared, and we emphasize the importance of obtaining fetal MR imaging to establish an accurate diagnosis.T he terminal spine presents unique imaging challenges, particularly in the case of large cystic masses. In the first case, an isolated terminal myelocystocele mimicked a cystic sacrococcygeal teratoma (SCT) on prenatal sonography. The second case of type 2 (SCT) is presented for comparison. We discuss the presentation and perinatal risks of these 2 cystic sacrococcygeal masses and illustrate surgical correction of a cystic terminal myelocystocele. Case Reports Index CaseA 22-year-old gravida 2, para 1 was referred to us for investigation of a fetal mass. Maternal serum alpha-fetoprotein (AFP) levels were mildly elevated, and amniocentesis results were a healthy female with normal acetylcholinesterase levels.At 30-weeks gestational age, sonography showed a cystic exophytic lower pelvic mass measuring 8 ϫ 7 ϫ 6 cm. The mass was skin-covered and septate ( Fig 1A, -B). It appeared to originate from the tip of an otherwise normal sacrum. Fetal calvaria views were normal, without Chiari II malformation. Amniotic fluid index (AFI) measured 21 cm, and fetal size was appropriate for gestational age. The size, location, and cystic composition of the mass and the perceived absence of skeletal dysraphism and Chiari II malformation supported the diagnosis of cystic SCT with complicating polyhydramnios. Fetal MR imaging was recommended to better characterize the mass; however, the patient refused due to claustrophobia. The follow-up fetal sonography at 36 weeks showed the mass had grown (10 ϫ 10 ϫ 6 cm) and the AFI had increased to 24 cm.At 37 weeks, the neonate was delivered via classic cesarean delivery without complications, weighing 3765 g with Apgar scores of 2, 5, and 8, at 1, 5, and 10 minutes, respectively. The mode of delivery was based on the prenatal diagnosis of a large SCT.Neonatal CT and MR imaging of the congenital cyst and spine revealed sacral spinal dysraphism and tethered cord (Fig 1C, -D). The diagnosis was revised to terminal myelocystocele.Surgical exploration was undertaken at 7 days of life ( Fig 1E, -F). The large cyst was entered and found to contain clear CSF in a terminal continuation of the spinal subarachnoid space. A second thinwalled cyst encountered at the base of the larger cyst represented terminal dilation of the spinal cord central canal (Fig 1G). These findings are diagnostic of terminal myelocystocele.1 Opening the second cyst revealed the true spinal canal, with lipomatous distal tethering of the cord to the dorsal and cranial aspect of the myelocystocele ( Fig 1H). Primary spinal cord untethering was undertaken, and the spinal canal was closed by using duraplasty material. Postoperatively, the neonate retained normal neurologic and urologic function....

Three‐dimensional power Doppler sonography in the diagnosis of a cystic sacrococcygeal teratoma mimicking a meningomyelocele: A case report

“…At autopsy, the fetus was noted to have a cystic SCT. In contrast, Yu et al 9 reported a case in which prenatal findings were interpreted as indicative of a cystic SCT, but postnatally the infant proved to have a myelocystocele. In addition, both cystic SCT and neural tube defects such as meningomyelocele and myelocystocele may be associated with elevated alpha-fetoprotein levels in maternal serum and amniotic fluid.…”

“…9 Evans et al 4 reported a case in which an incorrect prenatal diagnosis of fetal meningomyelocele led to termination of pregnancy at 17 weeks. At autopsy, the fetus was noted to have a cystic SCT.…”

Prenatal Diagnosis of Tethered Spinal Cord

“…14 Skin-covered lesions rarely demonstrate hindbrain malformation, hydrocephalus, or other findings of Chiari 2 malformation and are therefore generally more subtle and more difficult to diagnose in utero. 15,16 The In this case, the T12 and S1 levels of a normal 16-week-old spine are identified. maternal serum >-fetoprotein (AFP) levels are often normal or only minimally elevated when these anomalies are present.…”

Sacrococcygeal Teratoma - An Interesting Case and Infrequently seen Extension in Spinal Cord

“…Differential diagnosis which are considered and can be differentiated on the basis of MRI, ultrasound and pathological examination includes Extraspinal ependymoma, Ependymoblastoma, Neuroblastoma, Rhabdomyosarcoma and Terminal myelocystocele [8,9]. Treatments of SCT that have spinal extension consist of complete resection of the tumor followed by close follow up.…”