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Intradural dermoid tumor of the posterior fossa in a child with diastematobulbia
Surgical Neurology 63 (2005) 571 – 575 www.surgicalneurology-online.com
Neoplasm
Intradural dermoid tumor of the posterior fossa in a child with diastematobulbia Alexandru Vlad Ciurea, MDa,*, Teodora Coman, MDa, Alexandru Tascu, MDa, Virgil Ionescu, MDb Departments of aNeurosurgery, and bRadiology, Clinic Hospital bBagdasar-Arseni,Q Bucharest 75622, Romania Received 19 May 2004; accepted 28 June 2004
Abstract
Dermoid tumors (DTs) are rare lesions and represent 0.3% of all intracranial tumors. More than 50% of these tumors are diagnosed in childhood or early adolescence. Authors report an intradural DT of the posterior fossa in a child aged 4 years, possibly originating in the brainstem in which the diastematobulbia was detected postoperatively. Magnetic resonance imaging investigations are mandatory to diagnose these cases. The only curative treatment in DT is the total removal of the lesion. The reported case presents good recovery in the follow-up period of 3 years. The surgical intervention is particularly related to the DT type. Diastematobulbia associated with DT and the origin of the DT in the brainstem is discussed based on the literature. D 2005 Elsevier Inc. All rights reserved.
Keywords:
Dermoid tumor; Posterior fossa; Diastematobulbia; Child; MRI
1. Introduction Dermoid tumors (DTs) are less common than epidermoid cysts and constitute approximately 0.3% of all intracranial tumors [3,5,8,10]. They generally grow more quickly than epidermoids and become symptomatic at an earlier age. More than 50% of these tumors are diagnosed in childhood or early adolescence [8,22]. Dermoid tumors may arise anywhere along the cranial midline axis, including the third ventricle [8]. Approximately one third is in the fourth ventricular region [8,10,22]. For calvarial lesions, the common location is in the midline near the anterior fontanel whereas intradural lesions are found in the midline frontal skull base [10,18,20]. Its common position in the posterior fossa may contact the skin through a narrow isthmus or sinus tract. Intradural dermoids and epidermoid tumors usually grow slowly and often are quite large before they become symptomatic. They are more often solid than cystic. In most cases, these tumors have associated congenital anomalies.
* Corresponding author. Tel.: +40 216 836 895; fax: +40 213 347 350. E-mail addresses: [email protected] (A.V. Ciurea)8 [email protected] (T. Coman). 0090-3019/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2004.06.024
Dermoid tumors do not have a gender preponderance, with onset typically occurring during childhood [10,17]. 2. Case report A 4-year-old boy presented with headache associated with vomiting, swallowing complaints, and visual impairment of 6 months duration before admission. During this period, the boy presented 7 episodes of aseptic meningitis and was treated in a pediatric department. The neurological examination showed ataxia, sixth left nerve paresis, ninth to tenth nerve impairment, mild spastic tetraparesis predominant on the right side, bilateral papilledema, and horizontal gaze-evoked nystagmus. The presumptive clinical diagnosis leads to a posterior fossa mass. A psychological profile was performed to appreciate the postoperative psychological deterioration index in comparison with children of same age. The following tests were performed: Wechsler Intelligence Scale for Children, Rey Memory Test, Bender-Santucci Test, Social Emotional Scale, and Galveston Orientation Amnesia Test. On magnetic resonance imaging (MRI), the T1-weighted images showed hypointense lesion extended transmedullary from fourth ventricle to the premedullary subarachnoidal
572
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Fig. 1. Preoperative MRI T1-weighted image, the hypointense mass in the posterior fossa.
spaces with cerebellar compression and mild dilatation of the third and lateral ventricle (Figs. 1 and 2). The T2weighted images showed a homogeneous high signal intensity lesion (Figs. 3 and 4). No associated dermal sinus tract was noticed at the clinical and radiological investigations. The preoperative diagnosis was cystic tumor of posterior fossa. A midline craniotomy was performed. The DT was located intradurally, on the midline, having a thin capsula. No associated dermal sinus was seen pre- and intraoperatively. The tumor was completely removed microscopically. The pathological diagnosis was cystic mass with fibrous capsule lined with squamous epithelium and dermal adnexae, filled by thick fluid, and composed of cholesterol and keratin lamellae, lipid metabolites, and sebaceous debris that pleaded for the diagnosis of DT. The 1 year postoperative neurological status showed ataxia, seventh peripheral left nerve paresis, bilateral sixth
Fig. 2. Preoperative MRI T1-weighted image, the hypointense mass in the brainstem.
Fig. 3. Preoperative MRI T2-weighted image shows a homogeneous high signal intensity lesion in the posterior fossa.
nerve paresis predominant on the left side, and neocerebellar signs. At 3 years follow-up, the neurological status improved to mild ataxia, seventh peripheral left nerve paresis, bilateral sixth nerve paresis, and neocerebellar signs. The neurological signs were improved and the outcome was a good recovery with adequate social reinsertion of the child. The psychological set of tests showed no deterioration in comparison with children of the same age. The computed tomography (CT) scan performed 1 year postoperatively showed no pathological features in the tumor bed, but MRI performed at 1 and 3 years postoperative showed a malformation of the brainstem diagnosed as diastematobulbia on the neuroimaging (Figs. 5-8). This diagnosis was misleading before the surgical intervention
Fig. 4. Preoperative MRI T2-weighted image shows a homogeneous high signal intensity lesion in the brainstem.
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573
Fig. 5. Postoperative CT scan (1 year), hypodense area at the posterior fossa without mass effect, diastematobulbia.
due to the DT that filled the fourth ventricle and compressed the brainstem and the cerebellum. 3. Discussion The DT is usually found in the midline and its common position in the posterior fossa may contact the skin through a narrow isthmus or sinus tract [1]. Dermoid tumors of the posterior fossa tend to lie in the midline of the skull, outside or within the dura mater [15]. Logue and Till [15] classified posterior fossa DTs into 4 groups, depending on whether they were extradural or intradural, and on the degree of
Fig. 6. Postoperative MRI T1-weighted image (3 years), diastematobulbia.
development of the dermal sinus, whether absent, partial, or complete: (1) (2) (3) (4)
extradural DT with a complete sinus, intradural DT without a dermal sinus, intradural DT with an incomplete dermal sinus, intradural DT with a complete dermal sinus.
According to this classification, the reported case is a grade 2 DT. Dermoid tumors are also found frequently at the anterior fontanels and the occipital region of children [6,16,19]. Klippel-Feil syndrome in association with a posterior fossa DT was described [9,13]. Of the 153 patients with retethering of the cord, Herman et al [12] found that 38% had associated hydromyelia and 16% had an inclusion DT or epidermoid
Fig. 7. Postoperative MRI T1-weighted image (3 years), diastematobulbia.
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A.V. Ciurea et al. / Surgical Neurology 63 (2005) 571–575
aseptic meningitis developed before the diagnosis of DT. The initial radiological investigations do not show the DT, which misleading diagnosis of etiology. Malignancy in DTs has not been reported but is a theoretical possibility [1]. Dermoid tumors of the ventricles appear to be more easily removed. The young age of most of these patients and the more rapid growth of these tumors impose greater operative demands upon the surgeon. Surgery is the treatment of choice in DTs. The total resection is the goal of surgery. In cases with associated dermal sinus, the dermal tract must be closed to prevent recurrences (not applicable in our case). No other therapies are valid to treat DTs. Radiation therapy has no effect on DTs. Postoperative irradiation does not shrink these tumors, nor does it prevent their recurrence [14]. 4. Conclusion Fig. 8. Postoperative MRI T2-weighted image (3 years), diastematobulbia.
tumor. Dermoid tumors are commonly found within the cerebellum in the midline, usually associated with a dermal sinus [7,8]. Only 2 cases of DTs originating in the brainstem are reported in the literature [4,7]. Dermoid tumors located in the midline position are thought to derive from ectodermal remnants that remain within the closing neural tube at an early developmental stage, between the third and the fifth week of gestation [2]. For the tumors located more laterally, 2 main hypotheses are proposed: (1) proliferation of multipotential embryonic cells and (2) lateral displacement of the primitive ectodermal remnants along the developing otic vesicles or neurovasculature [3,4]. The neuroimaging evaluation is mandatory to diagnose DTs. A helpful clue for identification is a bony defect of the skull on plain film or on a bone window on CT scan [21]. In our case, this feature was not present. Approximately 20% of DTs have evidence of calcium deposition [10], but in this case, this feature was not present to help in the diagnosis. Dermoid tumors are easier to differentiate than epidermoid neoplasms on neuroimaging, because they have much greater lipid concentrations due to glandular secretion [11]. The DT contents have very low attenuation on CT scan. In MRI, the cyst contents are associated with very high signal intensity on T1-weighted sequences and with low signal intensity on T2weighted sequences [23]. In this case, the postoperative neuroimaging investigations showed a brainstem malformation diagnosed as diastematobulbia. This diagnosis was obscurant preoperatively because of the presence of DT that filled the fourth ventricle. This fact also explains the neurological signs including cranial nerve paresis. Because of the tendency for DTs to occur in the midline, obstruction of cerebrospinal fluid pathways is frequently the cause of initial signs and symptoms. Chemical meningitis may occur in cases of rupture. In our case, 7 episodes of
Dermoid tumors of the posterior fossa occur frequently in children. Aseptic meningitis occurs when communication with ventricles is present. The clinical particularity of this case is the insidious evolution before the diagnosis, characterized by 7 episodes of recurrent aseptic meningitis. The neuroimaging particularity of this case was the diastematobulbia discovered after the tumor removal. Surgery is the only treatment in these cases, and the total removal of the DT must be performed. Diastematobulbia is a congenital malformation possibly associated with DT.
References [1] Acciarri N, Padovani R, Foschini MP, et al. Intracranial squamous cell carcinoma arising in an epidermoid cyst. Br J Neurosurg 1993;7:565 - 9. [2] Baxter JW, Netsky MG. Epidermoid and dermoid tumors: pathology. In: Wilkins RH, Rengachary SS8 editors. Neurosurgery. New York7 McGraw-Hill; 1985. p. 655 - 61. [3] Berger MS, Wilson CB. Epidermoid cysts of the posterior fossa. J Neurosurg 1985;62:214 - 9. [4] Caldarelli M, Colosimo C, Di Rocco C. Intra-axial dermoid/epidermoid tumors of the brainstem in children. Surg Neurol 2001;56:97 - 105. [5] Cobb CA, Youmans JR. Brain tumors of disordered embryogenesis in adults. In: Youmans JR8 editor. Neurological surgery. 2nd ed. Philadelphia7 W.B. Saunders; 1982. p. 2899 - 935. [6] Crawford R. Dermoid cyst of the scalp: intracranial extension. J Pediatr Surg 1990;25:294 - 5. [7] Dunn LT, May PL, MacKenzie JM. Brain stem dermoid cyst. Childs Nerv Syst 1994;10:529 - 32. [8] Fleming JFR, Botterell EH. Cranial dermoid and epidermoid tumors. Surg Gynecol Obstet 1959;109:403 - 11. [9] Gonzalez-Darder JM, Feliu-Tatay R, Pesudo-Martinez JV, VeraRoman JM. Klippel-Feil syndrome associated with posterior fossa dermoid cyst. Case report. Neurol Res 2002;24:501 - 4. [10] Guidetti B, Gagliardi FM. Epidermoid and dermoid cyst: clinical evaluation and late surgical results. J Neurosurg 1977;47:12 - 8. [11] Hahn F, Ong E, McComb R, et al. MR imaging of rupture intracranial dermoid. J Comput Tomogr 1986;15:888 - 92. [12] Herman JM, McLone DG, Storrs BB, et al. Analysis of 153 patients with myelomeningocele or spinal lipoma reoperated upon for a tethered cord. Pediatr Neurosurg 1993;19:243 - 9.
A.V. Ciurea et al. / Surgical Neurology 63 (2005) 571–575
575
[13] Hinojosa M, Tatagiba M, Harada K, Samii M. Dermoid cyst in the posterior fossa accompanied by Klippel-Feil syndrome. Childs Nerv Syst 2001;17:97 - 100. [14] Keville FJ, Wise BL. Intracranial epidermoid and dermoid tumors. J Neurosurg 1959;16:564 - 9. [15] Logue V, Till K. Posterior fossa dermoid cysts with special reference to intracranial infection. J Neurol Neurosurg Psychiatry 1952;15:1 - 12. [16] Martı´nez-Lage JF, Ramos J, Puche A, Poza M. Extradural dermoid tumours of the posterior fossa. Arch Dis Child 1997;77:427 - 30. [17] Ozgen T, Oge HK, Erbengi A, et al. Cranial dermoid and epidermoid cysts. Neurochirurgia (Stuttg) 1990;33:16 - 9. [18] Pannell BW, Hendrick BE, Hoffman HJ, et al. Dermoid cyst of the anterior fontanelle. Neurosurgery 1982;10:317 - 23. [19] Peter JC, Sinclair-Smith C, DeVilliers JC. Midline dermal sinuses and cysts and their relationship to the central nervous system. Eur J Pediatr Surg 1991;1:73 - 9. [20] Rubin G, Scienza R, Pasqualin A, et al. Craniocerebral epidermoids and dermoids: a review of 44 cases. Acta Neurochir (Wien) 1989;97: 1 - 16. [21] Starinsky R, Wald U, Michowitz SD, Lahat E, Schiffer J. Dermoids of the posterior fossa. Case reports and review. Clin Pediatr (Phila) 1988; 27:579 - 82. [22] Sweet WH. A review of dermoid, teratoid and teratomatous intracranial tumors. Dis Nerve Syst 1940;1:228 - 38. [23] Wilms G, Casselman J, Demaerel PH, et al. CT and MRI of ruptured intracranial dermoids. Neuroradiology 1991;33:149 - 51.
the splitting of the brainstem as a secondary phenomenon due to the progressive growth of the tumor within the brainstem could, however, account for the association of the two lesions that could then be explained on the basis of a unique pathogenetic mechanism. In 1991, Obana and Wilson [1] discussed the apparent intraaxial location of some dermoid/intradermoid cysts of the posterior cranial fossa. The authors propounded that the phenomenon could actually correspond to the progressive invasion and splitting of the brainstem caused by the growth of ectodermal remnants primarily developing around the basilar artery rather than to a primary development of these cysts within the brainstem. A similar event could also take place due to the development of ectodermal remnants that remain entrapped within the closing neural tube in an early developmental stage to reach their definitive intraaxial location along the Virchow-Robin space. In my opinion, the apparent normality of the cerebellar vermis on the preoperative MRI studies of this patient here considered could favor the pre-ponto-bulbar origin of the cyst, at least in this particular case.
Commentary
[1] Obana WG, Wilson CB. Epidermoid cysts of the brainstem. Report of three cases. J Neurosurg 1991;74:123 - 8.
Dr Ciurea and colleagues report an interesting case of an intracranial DT developing within a split brain stem. The authors incline to interpret their case as the association of DT with malformation of the brain stem (diastematobulbia). The malformation would have become apparent only after the excision of the tumor. An alternative interpretation that is
Reference
Concezio Di Rocco, MD Istituto di Neurochirurgia Universita` Cattolica del Sacro Rome, 00168 Italy
Neoplasm
Intradural dermoid tumor of the posterior fossa in a child with diastematobulbia Alexandru Vlad Ciurea, MDa,*, Teodora Coman, MDa, Alexandru Tascu, MDa, Virgil Ionescu, MDb Departments of aNeurosurgery, and bRadiology, Clinic Hospital bBagdasar-Arseni,Q Bucharest 75622, Romania Received 19 May 2004; accepted 28 June 2004
Abstract
Dermoid tumors (DTs) are rare lesions and represent 0.3% of all intracranial tumors. More than 50% of these tumors are diagnosed in childhood or early adolescence. Authors report an intradural DT of the posterior fossa in a child aged 4 years, possibly originating in the brainstem in which the diastematobulbia was detected postoperatively. Magnetic resonance imaging investigations are mandatory to diagnose these cases. The only curative treatment in DT is the total removal of the lesion. The reported case presents good recovery in the follow-up period of 3 years. The surgical intervention is particularly related to the DT type. Diastematobulbia associated with DT and the origin of the DT in the brainstem is discussed based on the literature. D 2005 Elsevier Inc. All rights reserved.
Keywords:
Dermoid tumor; Posterior fossa; Diastematobulbia; Child; MRI
1. Introduction Dermoid tumors (DTs) are less common than epidermoid cysts and constitute approximately 0.3% of all intracranial tumors [3,5,8,10]. They generally grow more quickly than epidermoids and become symptomatic at an earlier age. More than 50% of these tumors are diagnosed in childhood or early adolescence [8,22]. Dermoid tumors may arise anywhere along the cranial midline axis, including the third ventricle [8]. Approximately one third is in the fourth ventricular region [8,10,22]. For calvarial lesions, the common location is in the midline near the anterior fontanel whereas intradural lesions are found in the midline frontal skull base [10,18,20]. Its common position in the posterior fossa may contact the skin through a narrow isthmus or sinus tract. Intradural dermoids and epidermoid tumors usually grow slowly and often are quite large before they become symptomatic. They are more often solid than cystic. In most cases, these tumors have associated congenital anomalies.
* Corresponding author. Tel.: +40 216 836 895; fax: +40 213 347 350. E-mail addresses: [email protected] (A.V. Ciurea)8 [email protected] (T. Coman). 0090-3019/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.surneu.2004.06.024
Dermoid tumors do not have a gender preponderance, with onset typically occurring during childhood [10,17]. 2. Case report A 4-year-old boy presented with headache associated with vomiting, swallowing complaints, and visual impairment of 6 months duration before admission. During this period, the boy presented 7 episodes of aseptic meningitis and was treated in a pediatric department. The neurological examination showed ataxia, sixth left nerve paresis, ninth to tenth nerve impairment, mild spastic tetraparesis predominant on the right side, bilateral papilledema, and horizontal gaze-evoked nystagmus. The presumptive clinical diagnosis leads to a posterior fossa mass. A psychological profile was performed to appreciate the postoperative psychological deterioration index in comparison with children of same age. The following tests were performed: Wechsler Intelligence Scale for Children, Rey Memory Test, Bender-Santucci Test, Social Emotional Scale, and Galveston Orientation Amnesia Test. On magnetic resonance imaging (MRI), the T1-weighted images showed hypointense lesion extended transmedullary from fourth ventricle to the premedullary subarachnoidal
572
A.V. Ciurea et al. / Surgical Neurology 63 (2005) 571–575
Fig. 1. Preoperative MRI T1-weighted image, the hypointense mass in the posterior fossa.
spaces with cerebellar compression and mild dilatation of the third and lateral ventricle (Figs. 1 and 2). The T2weighted images showed a homogeneous high signal intensity lesion (Figs. 3 and 4). No associated dermal sinus tract was noticed at the clinical and radiological investigations. The preoperative diagnosis was cystic tumor of posterior fossa. A midline craniotomy was performed. The DT was located intradurally, on the midline, having a thin capsula. No associated dermal sinus was seen pre- and intraoperatively. The tumor was completely removed microscopically. The pathological diagnosis was cystic mass with fibrous capsule lined with squamous epithelium and dermal adnexae, filled by thick fluid, and composed of cholesterol and keratin lamellae, lipid metabolites, and sebaceous debris that pleaded for the diagnosis of DT. The 1 year postoperative neurological status showed ataxia, seventh peripheral left nerve paresis, bilateral sixth
Fig. 2. Preoperative MRI T1-weighted image, the hypointense mass in the brainstem.
Fig. 3. Preoperative MRI T2-weighted image shows a homogeneous high signal intensity lesion in the posterior fossa.
nerve paresis predominant on the left side, and neocerebellar signs. At 3 years follow-up, the neurological status improved to mild ataxia, seventh peripheral left nerve paresis, bilateral sixth nerve paresis, and neocerebellar signs. The neurological signs were improved and the outcome was a good recovery with adequate social reinsertion of the child. The psychological set of tests showed no deterioration in comparison with children of the same age. The computed tomography (CT) scan performed 1 year postoperatively showed no pathological features in the tumor bed, but MRI performed at 1 and 3 years postoperative showed a malformation of the brainstem diagnosed as diastematobulbia on the neuroimaging (Figs. 5-8). This diagnosis was misleading before the surgical intervention
Fig. 4. Preoperative MRI T2-weighted image shows a homogeneous high signal intensity lesion in the brainstem.
A.V. Ciurea et al. / Surgical Neurology 63 (2005) 571–575
573
Fig. 5. Postoperative CT scan (1 year), hypodense area at the posterior fossa without mass effect, diastematobulbia.
due to the DT that filled the fourth ventricle and compressed the brainstem and the cerebellum. 3. Discussion The DT is usually found in the midline and its common position in the posterior fossa may contact the skin through a narrow isthmus or sinus tract [1]. Dermoid tumors of the posterior fossa tend to lie in the midline of the skull, outside or within the dura mater [15]. Logue and Till [15] classified posterior fossa DTs into 4 groups, depending on whether they were extradural or intradural, and on the degree of
Fig. 6. Postoperative MRI T1-weighted image (3 years), diastematobulbia.
development of the dermal sinus, whether absent, partial, or complete: (1) (2) (3) (4)
extradural DT with a complete sinus, intradural DT without a dermal sinus, intradural DT with an incomplete dermal sinus, intradural DT with a complete dermal sinus.
According to this classification, the reported case is a grade 2 DT. Dermoid tumors are also found frequently at the anterior fontanels and the occipital region of children [6,16,19]. Klippel-Feil syndrome in association with a posterior fossa DT was described [9,13]. Of the 153 patients with retethering of the cord, Herman et al [12] found that 38% had associated hydromyelia and 16% had an inclusion DT or epidermoid
Fig. 7. Postoperative MRI T1-weighted image (3 years), diastematobulbia.
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A.V. Ciurea et al. / Surgical Neurology 63 (2005) 571–575
aseptic meningitis developed before the diagnosis of DT. The initial radiological investigations do not show the DT, which misleading diagnosis of etiology. Malignancy in DTs has not been reported but is a theoretical possibility [1]. Dermoid tumors of the ventricles appear to be more easily removed. The young age of most of these patients and the more rapid growth of these tumors impose greater operative demands upon the surgeon. Surgery is the treatment of choice in DTs. The total resection is the goal of surgery. In cases with associated dermal sinus, the dermal tract must be closed to prevent recurrences (not applicable in our case). No other therapies are valid to treat DTs. Radiation therapy has no effect on DTs. Postoperative irradiation does not shrink these tumors, nor does it prevent their recurrence [14]. 4. Conclusion Fig. 8. Postoperative MRI T2-weighted image (3 years), diastematobulbia.
tumor. Dermoid tumors are commonly found within the cerebellum in the midline, usually associated with a dermal sinus [7,8]. Only 2 cases of DTs originating in the brainstem are reported in the literature [4,7]. Dermoid tumors located in the midline position are thought to derive from ectodermal remnants that remain within the closing neural tube at an early developmental stage, between the third and the fifth week of gestation [2]. For the tumors located more laterally, 2 main hypotheses are proposed: (1) proliferation of multipotential embryonic cells and (2) lateral displacement of the primitive ectodermal remnants along the developing otic vesicles or neurovasculature [3,4]. The neuroimaging evaluation is mandatory to diagnose DTs. A helpful clue for identification is a bony defect of the skull on plain film or on a bone window on CT scan [21]. In our case, this feature was not present. Approximately 20% of DTs have evidence of calcium deposition [10], but in this case, this feature was not present to help in the diagnosis. Dermoid tumors are easier to differentiate than epidermoid neoplasms on neuroimaging, because they have much greater lipid concentrations due to glandular secretion [11]. The DT contents have very low attenuation on CT scan. In MRI, the cyst contents are associated with very high signal intensity on T1-weighted sequences and with low signal intensity on T2weighted sequences [23]. In this case, the postoperative neuroimaging investigations showed a brainstem malformation diagnosed as diastematobulbia. This diagnosis was obscurant preoperatively because of the presence of DT that filled the fourth ventricle. This fact also explains the neurological signs including cranial nerve paresis. Because of the tendency for DTs to occur in the midline, obstruction of cerebrospinal fluid pathways is frequently the cause of initial signs and symptoms. Chemical meningitis may occur in cases of rupture. In our case, 7 episodes of
Dermoid tumors of the posterior fossa occur frequently in children. Aseptic meningitis occurs when communication with ventricles is present. The clinical particularity of this case is the insidious evolution before the diagnosis, characterized by 7 episodes of recurrent aseptic meningitis. The neuroimaging particularity of this case was the diastematobulbia discovered after the tumor removal. Surgery is the only treatment in these cases, and the total removal of the DT must be performed. Diastematobulbia is a congenital malformation possibly associated with DT.
References [1] Acciarri N, Padovani R, Foschini MP, et al. Intracranial squamous cell carcinoma arising in an epidermoid cyst. Br J Neurosurg 1993;7:565 - 9. [2] Baxter JW, Netsky MG. Epidermoid and dermoid tumors: pathology. In: Wilkins RH, Rengachary SS8 editors. Neurosurgery. New York7 McGraw-Hill; 1985. p. 655 - 61. [3] Berger MS, Wilson CB. Epidermoid cysts of the posterior fossa. J Neurosurg 1985;62:214 - 9. [4] Caldarelli M, Colosimo C, Di Rocco C. Intra-axial dermoid/epidermoid tumors of the brainstem in children. Surg Neurol 2001;56:97 - 105. [5] Cobb CA, Youmans JR. Brain tumors of disordered embryogenesis in adults. In: Youmans JR8 editor. Neurological surgery. 2nd ed. Philadelphia7 W.B. Saunders; 1982. p. 2899 - 935. [6] Crawford R. Dermoid cyst of the scalp: intracranial extension. J Pediatr Surg 1990;25:294 - 5. [7] Dunn LT, May PL, MacKenzie JM. Brain stem dermoid cyst. Childs Nerv Syst 1994;10:529 - 32. [8] Fleming JFR, Botterell EH. Cranial dermoid and epidermoid tumors. Surg Gynecol Obstet 1959;109:403 - 11. [9] Gonzalez-Darder JM, Feliu-Tatay R, Pesudo-Martinez JV, VeraRoman JM. Klippel-Feil syndrome associated with posterior fossa dermoid cyst. Case report. Neurol Res 2002;24:501 - 4. [10] Guidetti B, Gagliardi FM. Epidermoid and dermoid cyst: clinical evaluation and late surgical results. J Neurosurg 1977;47:12 - 8. [11] Hahn F, Ong E, McComb R, et al. MR imaging of rupture intracranial dermoid. J Comput Tomogr 1986;15:888 - 92. [12] Herman JM, McLone DG, Storrs BB, et al. Analysis of 153 patients with myelomeningocele or spinal lipoma reoperated upon for a tethered cord. Pediatr Neurosurg 1993;19:243 - 9.
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575
[13] Hinojosa M, Tatagiba M, Harada K, Samii M. Dermoid cyst in the posterior fossa accompanied by Klippel-Feil syndrome. Childs Nerv Syst 2001;17:97 - 100. [14] Keville FJ, Wise BL. Intracranial epidermoid and dermoid tumors. J Neurosurg 1959;16:564 - 9. [15] Logue V, Till K. Posterior fossa dermoid cysts with special reference to intracranial infection. J Neurol Neurosurg Psychiatry 1952;15:1 - 12. [16] Martı´nez-Lage JF, Ramos J, Puche A, Poza M. Extradural dermoid tumours of the posterior fossa. Arch Dis Child 1997;77:427 - 30. [17] Ozgen T, Oge HK, Erbengi A, et al. Cranial dermoid and epidermoid cysts. Neurochirurgia (Stuttg) 1990;33:16 - 9. [18] Pannell BW, Hendrick BE, Hoffman HJ, et al. Dermoid cyst of the anterior fontanelle. Neurosurgery 1982;10:317 - 23. [19] Peter JC, Sinclair-Smith C, DeVilliers JC. Midline dermal sinuses and cysts and their relationship to the central nervous system. Eur J Pediatr Surg 1991;1:73 - 9. [20] Rubin G, Scienza R, Pasqualin A, et al. Craniocerebral epidermoids and dermoids: a review of 44 cases. Acta Neurochir (Wien) 1989;97: 1 - 16. [21] Starinsky R, Wald U, Michowitz SD, Lahat E, Schiffer J. Dermoids of the posterior fossa. Case reports and review. Clin Pediatr (Phila) 1988; 27:579 - 82. [22] Sweet WH. A review of dermoid, teratoid and teratomatous intracranial tumors. Dis Nerve Syst 1940;1:228 - 38. [23] Wilms G, Casselman J, Demaerel PH, et al. CT and MRI of ruptured intracranial dermoids. Neuroradiology 1991;33:149 - 51.
the splitting of the brainstem as a secondary phenomenon due to the progressive growth of the tumor within the brainstem could, however, account for the association of the two lesions that could then be explained on the basis of a unique pathogenetic mechanism. In 1991, Obana and Wilson [1] discussed the apparent intraaxial location of some dermoid/intradermoid cysts of the posterior cranial fossa. The authors propounded that the phenomenon could actually correspond to the progressive invasion and splitting of the brainstem caused by the growth of ectodermal remnants primarily developing around the basilar artery rather than to a primary development of these cysts within the brainstem. A similar event could also take place due to the development of ectodermal remnants that remain entrapped within the closing neural tube in an early developmental stage to reach their definitive intraaxial location along the Virchow-Robin space. In my opinion, the apparent normality of the cerebellar vermis on the preoperative MRI studies of this patient here considered could favor the pre-ponto-bulbar origin of the cyst, at least in this particular case.
Commentary
[1] Obana WG, Wilson CB. Epidermoid cysts of the brainstem. Report of three cases. J Neurosurg 1991;74:123 - 8.
Dr Ciurea and colleagues report an interesting case of an intracranial DT developing within a split brain stem. The authors incline to interpret their case as the association of DT with malformation of the brain stem (diastematobulbia). The malformation would have become apparent only after the excision of the tumor. An alternative interpretation that is
Reference
Concezio Di Rocco, MD Istituto di Neurochirurgia Universita` Cattolica del Sacro Rome, 00168 Italy