Perinatal/Neonatal Case Presentation Sirenomelia with an Angiomatous Lumbosacral Myelocystocele in a Full-term Infant

Marybeth Browne, MD cystic mass in the lumbosacral region of unknown etiology, and a Philip Fitchev, MD two-vessel umbilical cord. Cytogenetic analysis at that time revealed Brian Adley, MD a normal female fetus (46, XX). The infant was delivered at full Susan E. Crawford, MD term with Apgar scores of 0,0. A complete autopsy was performed. Gross examination of the infant displayed multiple external deformities including a single lower extremity with a single digit and absence of external genitalia or anus. Additionally, there was Sirenomelia, also known as the mermaid syndrome, is a rare congenital an obvious right-sided hypoplasia of the iliac bone, sacral agenesis, malformation of uncertain etiology. It is characterized by fusion of the multiple rib deformities, Potter’s facies, left-sided ear appendage, lower limbs and commonly associated with severe urogenital and and a large cystic lesion occupying the lumbosacral region. The gastrointestinal malformations. In this report, we describe the first case of cyst was retrotoneal, unilocular, and measured 17 Â 7 Â 2cmin an infant with sirenomelia and a massive angiomatous lumbosacral its greatest dimensions (Figure 1). It extended cephalad through myelocystocele. the soft tissues of the back and had a smooth lining filled with Journal of Perinatology (2004) 24, 329–331. doi:10.1038/sj.jp.7211085 serous fluid. Internally, the infant was noted to have severe bilateral lung hypoplasia, blind termination of the colon with proximal dilatation, and absence of the bladder, ureters, and bilateral kidneys. INTRODUCTION Radiographic pictures revealed a single distal leg with two Sirenomelia, also known as the mermaid syndrome, is a rare ossification centers consistent with a Stocker Type VI abnormality congenital anomaly characterized by lower limb fusion, and and several rib abnormalities (Figure 2). Histological evaluation of associated with severe urogenital and gastrointestinal the cystic mass revealed a skin-covered lesion lined by a thin layer malformations. With its physical resemblance to the mystical mermaid, the term ‘‘sirenomelia’’ was derived from the sirens of Greek and Roman mythology.1 Although the time of insult is known to be between 28 and 32 days of gestation, the pathogenesis of this malformation remains unclear, with some studies implicating caudal regression or vascular steal phenomenon.1–3 We will describe the first report of a fetus with sirenomelia and a massive angiomatous lumbosacral myelocystcele.

CASE REPORT A 40-week, 1760-g term female infant was born to a 22-year-old primigravida mother with no significant past medical history. During the prenatal ultrasound, oligohydramnios was noted as well as multiple congenital anomalies including an absent lower limb, absent bladder and kidneys, a malformed pelvis, scoliosis, a large

Department of Surgery (M.B), Children’s Memorial Hospital, USA; Department of Pathology (P.F., B.A., S.E.C.), Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. Figure 1. Infant with sirenomelia and lumbosacral myelocystocele. Address correspondence and reprint requests to Susan Crawford, MD, Feinberg School of Medicine, Northwestern University, Department of Pathology, 303 E Chicago Ave, w127, Chicago, Note the single lower extremity and the large lumbosacral cystic IL 60611, USA. structure, which extends cephalad through the soft tissues of the back.

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more common in males, having a higher incidence in identical twins, and having a slight increase in risk with maternal age of less than 20 years and older than 40 years.4,5 This syndrome was once thought to be uniformly fatal; however, since 1989, there have been four reports of children surviving with sirenomelia.6 The abnormalities found in these surviving children were variable and did not include renal agenesis; thus, demonstrating the unpredictable heterogeneity of the associated anomalies.6,7 Duhamel was the first to describe the associated anomalies of sirenomelia. He included sacral agenesis, imperforate anus, colonic or rectal atresia, renal agenesis, absent bladder, and absent internal genitalia.2 As a result of the renal agenesis, the description has come to include Potter’s syndrome, which consists of Potter’s facies (large low-set ears, epicanthal folds, hypertelorism, flattened nose, and receding chin), oligohydramnios, and pulmonary hypoplasia.4,8 In most cases, sirenomelia is found to have a Figure 2. X-ray examination of infant with sirenomelia. Note the single umbilical artery, considered a true artery with an abnormal multiple rib abnormalities, sacral agenesis, iliac hypoplasia, and single course. The unique point of origin for the single umbilical artery femur with two ossification centers. from the dorsal aortic trunk distinguishes this condition from others.1 There is great variability in the extent of the malformations within sirenomelia. Stocker and Heifetz1 classified the leg abnormalities into Types I through VII. Type I is the least severe with all bones present; and Type VII, most severe, consisting of a lower extremity with a fused femur and absent tibia and fibula.1 Our infant had a Stocker Type VI leg abnormality, the associated urogenital and gastrointestinal anomalies, and a lumbosacral myelocystocele. There have been three sirenomelia infants with meningomyeloceles; two with Arnold–Chiari’s malformation and one with significant hydrocephalus.1,3 This fetus had an unusual variant of a terminal or lumbosacral myelocystocele whereby the massive cyst was associated with sacral agenesis and spinal dysraphia with cystic dilatation around the Figure 3. Histopathology of myelocystocele. Cystic wall demonstrates 9 neural tissue with an ependymal lining. Note the cystic dilatation spinal cord. around the spinal cord and the marked angiogenesis and vascular There have been many theories about the etiology of the congestion in the adjacent fibromuscular tissue (H&E, 10 Â ). mermaid syndrome. In ancient times, many postulated about supernatural events, to consorting with a merman or an evil spirit, or to blaming a maternal experience or observation during of neural tissue. A mixture of neural elements was identified gestation.3 Currently, there are two major theories. First, Duhamel including neurons, peripheral nerves, and ependymal tissue. described the caudal regression syndrome to explain various Sections of the spinal cord revealed cystic dilatation around the congenital anomalies, sirenomelia being the most severe form. He cord with contiguous extension to the lumbosacral cyst. Marked postulated that a small localized lesion would lead to anal angiogenesis and vascular congestion was apparent in adjacent imperforation and mild vertebral anomalies; larger lesions would fibromuscular tissue (Figure 3). No additional elements were lead to urinary tract and gastrointestinal malformations; and lastly, identified excluding the possibility of a sacroccygeal teratoma. extreme lesions would cause lower limb fusion and anomalies associated with sirenomelia.2 This theory was popular for many years until Stevenson described an alternate theory of vascular steal DISCUSSION that has recently taken favor over caudal regression for the Sirenomelia is a rare congenital malformation, which occurs in mermaid syndrome. Stevenson et al.3 explain that in the mermaid 1.05 out of 100,000 births.4 It is described as being three times syndrome, blood is diverted from the caudal region of the embryo

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to the placenta producing a nutritional deprivation and abnormal References development of the caudal structures. The site at which the steal 1. Stocker JT, Heifetz SA, Sirenomelia. A morphological study of 33 cases and occurs determines the severity of the anomalies.3 The mechanism review of the literature. Perspect Pediatr Pathol 1987;10:7–50. of this discrepancy is not fully understood. Both theories may be 2. Duhamel B. From the mermaid to anal imperforation: the syndrome of oversimplifications of the true etiology of sirenomelia, since neither caudal regression. Arch Dis Child 1961;36:153–5. explains the noncaudal anomalies, which have been seen in some 3. Stevenson RE, Lyons Jones K, Phelan MC, et al. Vascular steal: the instances.7 Few have noted drug use in mothers of sirenomelia pathogenetic mechanism producing sirenomelia and associated defects of the viscera and soft tissues. Pediatre 1986;78(3):451–7. children; however, no substance has ever been proven to be the 1,6,8 4. Kallen B, Castilla EE, Lancaster PA, et al. The cyclops and the mermaid: teratogenic cause of sirenomelia. Maternal diabetes is 200 times an epidemiological study of two types of rare malformation. J Med Genet more likely in children with caudal regression syndrome; however, 1992;29:30–5. Stocker has failed to confirm this association in his series, where 5. Schiesser M, Holzgreve W, Lapaire O, et al. Sirenomelia, the mermaid maternal diabetes was rarely seen in connection with syndrome F detection in the first trimester. Prenat Diagn 2003;23:493–5. sirenomelia.1,10 6. Stanton MP, Penington EC, Hutson JM. A surviving infant with sirenomelia Early antenatal diagnosis should be made prior to the dramatic (mermaid syndrome) associated with absent bladder. J Pediatr Surg 2003; decrease in amniotic fluid.5 This is achieved by sonographic 38(8):1266–8. demonstration of constant simultaneous movement of the lower 7. Murphy JJ, Fraser GC, Blair GK. Sirenomelia: case of the surviving limbs, skeletal abnormalies in the lower extremities, and mermaid. J Pediatr Surg 1992;27(10):1265–68. oligohydramnios related to kidney agenesis.5,11 The progressive 8. Goodlow OG, McCoy Sibley RI, Allen BG, et al. Sirenomelia: mermaid oligohydramnios, noted in the second trimester, can be the first syndrome. J Natl Med Assoc 1988;80(3):343–46. 9. Mclone DG, Naidich TP. Terminal myelocystocele. Neurosurgery 1985; sign of this malformation; however, with severe oligohydramnios, a 5,11 16(1):36–43. prenatal diagnosis may be difficult. This is the first reported 10. Zaw W, Stone DG. Caudal regression syndrome in twin pregnancy with type case of a sirenomelia with a massive angiomatous lumbosacral II diabetes. J Perinatol 2002;22:171–4. myelocystocele. Despite a cystic structure being noted on prenatal 11. Valenzano M, Paoletti R, Rossi A, et al. Sirenomelia. Pathological features, ultrasound, the size of the mass obscured the ability to render a antenatal ultrasonographic clues, and review of current embryogenic theories. definitive diagnosis until postmortem evaluation. Hum Reprod Update 1999;5(1):82–6.

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