J Neurosurg (4 Suppl Pediatrics) 105:326–328, 2006
Possible genetic correlation of an occipital dermal sinus in a mother and son Case report SAEED ANSARI, M.D., MAJID DADMEHR, M.D., AND FARIDEH NEJAT, M.D. Department of Neurosurgery and Children’s Hospital Medical Center, Tehran University of Medical Sciences, Tehran, Iran
POccipital dermal sinuses (ODSs) are congenital lesions located in the midline and characterized by a cutaneous pit or dimple. The intracranial extension as well as the associated symptoms are variable. To date, a familial occurrence of these lesions has not been reported. In this paper the authors report on a 2-year-old boy with an ODS and intracranial hypertension. The boy’s mother had a similar lesion but did not have any complaints. Following their experience with this case and a literature review, the authors suggest that there may be a genetic basis in certain instances of ODS. KEY WORDS • occipital dermal sinus • dysraphism • pediatric neurosurgery
CCIPITAL dermal sinuses are rare dysraphic lesions that result from defective separation of the ectoderm and neuroectoderm during the 3rd to 5th weeks of gestation.8 These benign lesions are usually discovered along with recurrent meningitis, cerebellar abscess, or a cutaneous opening infection and are treated soon after diagnosis because of potentially life-threatening complications.5,10 The pathogenesis of these rare lesions is still poorly understood, although authors of previous studies have suggested that ODSs may be inherited.9,10 To draw attention to the familial occurrence of ODS, we report on a mother and son who had ODSs.
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Case Report History and Examination. This 2-year-old boy presented with headache, vomiting, and gait disturbance. He was the first child of nonconsanguineous parents and had no significant medical history. He had experienced worsening of his symptoms 3 weeks prior to presentation. On physical examination, the child was afebrile and had papilledema, right sixth cranial nerve palsy, and signs of cerebellar dysfunction. A dimple was noted at the midline occipital area above the inion. The lesion was surrounded by a few thick black hairs and occasionally it produced a white creamy discharge (Fig. 1). Brain MR imaging was performed, which revealed Abbreviations used in this paper: MR = magnetic resonance; NTD = neural tube defect; ODS = occipital dermal sinus.
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the ODS and intracranial extension of the sinus tract toward a large posterior fossa mass. The lesion was hypointense on T1-weighted and hyperintense on T2-weighted images that were indicative of a dermoid tumor accompanied by severe hydrocephalus (Fig. 2). The mother claimed that she had the same lesion since birth, and she was found to have a similar dimple exactly in the same area (Fig. 3). She denied having experienced any previous infection and therefore did not undergo further examination. Operation and Postoperative Course. The boy underwent a midline occipital craniectomy including resection of the sinus, intracranial tract, and posterior fossa dermoid tumor. His postoperative period was uneventful. Discussion Neural tube defects are a group of widely varying congenital malformations and are caused by a combination of many genetic and environmental factors.6,9 Congenital ODSs are a form of closed NTD that can occur anywhere along the craniospinal axis,5 least commonly in the calvaria and most commonly in the occipital region.7,8 The diagnosis of these lesions is generally made by the infant’s pediatrician or general practitioner during routine examination at birth. The typical finding at birth is a dimple surrounded by a tuft of abnormally thick and dark hair. A wide spectrum of clinical manifestations ranging from asymptomatic ODS to serious complications such as neuJ. Neurosurg: Pediatrics / Volume 105 / October, 2006
Occipital dermal sinus in a mother and son
FIG. 3. Photograph (posterior view) of the mother’s head revealing an uncomplicated ODS with thick black hair protruding from its opening.
FIG. 1. Photograph (posterior view) of the child’s head, which was shaved and prepared for operation, showing a small opening in the midline occipital area (arrow) above the occipital protuberance.
raxial infection and cerebellar abscess8 with hydrocephalus can occur; there is no apparent time frame for an asymptomatic lesion to later become symptomatic.10 It appears that most infections occur when the patient is between 1 and 20 years old. If the patient reaches the upper limits of this age range without having experienced an infection, it is most likely that the dermal sinus is closed.10 Magnetic resonance imaging is highly useful in identifying the sinus tract; its relationship to the tentorium, torcular herophili, and straight sinus; and its intracranial extension.7,8,10 Although less attention has been focused on the role that genetics plays in cases of closed NTDs, there is evidence that at least some of the underlying causes are common in
cases of open and closed NTDs. Familial aggregation noted in several families suggests that there may be a genetic origin.9 There is evidence of a possible genetic link such as a pair of monochorial twins, one with ODS and the other with cerebellar hypoplasia and occipital meningocele;4 two siblings, one with ODS and the other with myelomeningocele; association of ODS with Klippel–Feil syndrome;10 increased prevalence in certain ethnic groups;3 and higher incidences of ODS in females3,10 and children born to consanguineous parents.3 Therefore the role of genetics in the pathogenesis of this disorder is probable.9,10 Familial occurrence of some kinds of closed NTDs such as lipomyelomeningocele,6,9 syringomyelia,11,12 diastematomyelia,1 and frontonasal dermoid cysts2 has been reported previously, but in our comprehensive MEDLINE search of articles published between 1966 and 2005, we did not identify any case of familial ODS. The complexity of genetic mechanisms underlying NTDs are illustrated by a myriad of reports in which the authors have described autosomal-dominant, autosomal-recessive,
FIG. 2. Left: Sagittal T1-weighted MR image showing the opening of the dermal sinus above the inion and the extension of the tract through the skull into the posterior fossa. Note the large intradural mass (dermoid tumor) causing fourth ventricle compression. Right: Axial T2-weighted MR image showing the large hyperintense mass posterior to the fourth ventricle.
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S. Ansari, M. Dadmehr, and F. Nejat and X-linked patterns of inheritance within some families.3 In our case, we could not identify a definite inheritance pattern, but the passage of the trait from mother to son may support the concept of an autosomal-dominant inheritance. We present this case to emphasize the importance of examining the close relatives of affected individuals to identify cases of familial ODS, and to predict and prevent the potential complications and further evaluate the probable role of genetics in this abnormality. In conclusion, more studies with larger groups of familial samples will be necessary before these results can be clinically used to counsel parents regarding the risk of inheritance of this lesion. References 1. Balci S, Caglar K, Eryilmaz M: Diastematomyelia in two sisters. Am J Med Genet 86:180–182, 1999 2. Bratton C, Suskind DL, Thomas T, Kluka EA: Autosomal dominant familial frontonasal dermoid cysts: a mother and her identical twin daughters. Int J Pediatr Otorhinolaryngol 57:249–253, 2001 3. Dirks PB, Rutka JT: The genetic basis of neurological disorders, in Youmans JR (ed): Neurological Surgery, ed 4. Philadelphia: WB Saunders, 1996, pp 811–829 4. Groen RJ, van Ouwerkerk WJ: Cerebellar dermoid tumor and occipital meningocele in a monozygotic twin: clues to the embryogenesis of craniospinal dysraphism. Childs Nerv Syst 11: 414–417, 1995
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5. Higashi S, Takinami K, Yamashita J: Occipital dermal sinus associated with dermoid cyst in fourth ventricle. AJNR Am J Neuroradiol 16:945–948, 1995 6. Kannu P, Furneaux C, Aftimos S: Familial lipomyelomeningocele: a further report. Am J Med Genet A 132:90–92, 2005 7. McComb JG: Encephaloceles, in Youmans JR (ed): Neurological Surgery, ed 4. Philadelphia: WB Saunders, 1996, pp 829–842 8. Nejat F, Dias MS, Eftekhar B, Nasri Roodsari N, Hamidi S: Bilateral retro-auricular dermal sinus tracts with intradural extension. Case report. J Neurosurg 99:163–166, 2003 9. Sebold CD, Melvin EC, Siegel D, Mehltretter L, Enterline DS, Nye JS, et al: Recurrence risks for neural tube defects in sibling of patients with lipomyelomeningocele. Genet Med 7:64–67, 2005 10. Vinchon M, Soto-Ares G, Assaker R, Belbachir F, Dhellemmes P: Occipital dermal sinuses: report of nine pediatric cases and review of literature. Pediatr Neurosurg 34:255–263, 2001 11. Yabe I, Kikuchi S, Tashiro K: Familial syringomyelia: the first Japanese case and review of the literature. Clin Neurol Neurosurg 105:69–71, 2002 12. Zakeri A, Glasauer FE, Egnatchik JG: Familial syringomyelia: case report and review of literature. Surg Neurol 44:48–53, 1995
Manuscript received February 13, 2006. Accepted in final form July 12, 2006. Address reprint requests to: Farideh Nejat, M.D., Mailbox: Iran, Tehran, F. Nejat, 14155–7854. email:
[email protected].
J. Neurosurg: Pediatrics / Volume 105 / October, 2006
