Case of the Week

Background:

• The Currarino syndrome/ASP triad is a complex condition variably comprising characteristic congenital anomalies of the sacrum, anorectum, and presacral soft tissues. If all 3 features are not always present, then it is called incomplete Currarino syndrome. This can be familial or sporadic, with an autosomal dominant inheritance mode.

Clinical Presentation:

• This condition may be detected and diagnosed antenatally or peripartum; it is not typically diagnosed after the first month of life. However, the incomplete form of the syndrome may remain undiagnosed until the patient is older (80% of cases are diagnosed before the patient is 16 years old).

Key Diagnostic Features:

• Anorectal malformation (which is absent in our case), sacrococcygeal osseous defect (always present, eg, scimitar sacrum/sickle-shaped sacrum/hemisacral agenesis is a unilateral, well-marginated, crescent-shaped defect in the lateral sacrum), presacral mass (anterior meningocele represents approximately 50% of presacral masses, teratoid tumor represents 40%, and the remaining include neuroeneteric, anal duplication cyst, immature teratoma, hamartoma, nephroblastoma, primitive neuroendocrine tumor, epidermoid [as in our case], dermoid cyst, or lipoma)
• Rare associations: thickened terminal filum, syringomyelia, low conus medullaris, and tethered cord (as in our case)
• Other associated manifestations include malformations of the urogenital system that comprise horseshoe kidneys, sigmoid kidneys, single pelvic kidneys, neurogenic bladders, multicystic kidneys, vesicouretral reflux, and partial or complete duplication of the vagina, clitoris, or uterus.

Differential Diagnoses:

• Isolated sacrococcygeal teratoma: associated anterior sacral meningocele and scimitar sacrum helps in diagnosis. Most often presents in the postcoccygeal region. The underlying sacral bone is often normal, and no anal malformations are associated.
• Neurogenic tumors: solid/mixed cystic mass with enhancing solid components and lack of additional findings 
• Caudal regression syndrome: lumbosacral agenesis and anal atresia. The sacral defect tends to be more extensive, involving the first sacral vertebra and often the lumbar and thoracic vertebrae as well. There is no association with a presacral mass.
• Isolated sacral agenesis: as a consequence of diabetic embryopathy or of unknown cause. No presacral mass or anorectal malformations are usually noted.

Treatment:

• Surgery: Sacral laminectomy is the most widely used approach for cases in which no presacral mass is present. The anterior approach has been used when a pelvic mass is present or the neck of the meningocele is too large to ligate (as in our case). The posterior midsagittal approach has been used for cases with associated anorectal anomalies.
• Collaboration of a multidisciplinary surgical team (a pediatric or spine neurosurgeon, a general surgeon, and, for girls, a gynecological surgeon) is essential for optimal outcome in most cases. Long-term neuroimaging follow-up is recommended after surgical repair in cases with complete or incomplete Currarino syndrome.
• Early diagnosis with adequate treatment prevents eventual serious complications including meningitis from fistula to the thecal sac or from bone erosion, meningocele rupture, perianal sepsis, urinary tract infection, and, rarely, malignant transformation of a teratoma.
• In addition, given that autosomal dominant inheritance is likely in this disorder and that early diagnosis and treatment are important, whenever a patient with Currarino syndrome is identified, other members of the patient’s family, particularly young children, should be evaluated for the condition. One-half of cases are due to an autosomal dominant mutation in the HLXB9 (MNX1) gene (on chromosome 7q36).