J Neurosurg 73:788-791, 1990
Intradural epithelial cyst at the craniovertebral junction Case report ROBERT E. BREEZE, M.D., PETER NICHOLS, M.D., HERVEY SEGAL, M.D., AND MICHAEL L. J. A e u z z o , M.D.
Division of Neurosurgery, University of Colorado Health Sciences Center, Denver, Colorado; and Departments of Pathology, Radiology (Neuroradiology), and Neurological Surgery, University of Southern California School of Medicine, Los Angeles, California o- A case of an intradural epithelial cyst at the craniovertebral junction is reported in a 37-year-old man. The classification of these rare lesions is discussed. KEY WORDS 9 cyst, intradural craniovertebral junction
T
HE term "intradural epithelial cyst" is used in this report to identify those lesions commonly referred to as "ependymal cysts," "enterogenous cysts," and "teratomatous cysts." Excluded from discussion are epidermoid and dermoid cysts, solid teratomas, and colloid cysts; although these lesions may be found in the spinal canal and contain epithelial tissue, they are easily distinguished from the much rarer thinwalled fluid-filled cysts, herein called "intradural epithelial cysts." Seventy-seven intradural epithelial cysts have been reported in the literature under different terms (Table 1). 1,3,5-7,9-11,13-16,18,19 This communication describes the first reported case of an enterogenous cyst at the craniovertebral junction and the first intradural epithelial cyst to be identified by magnetic resonance (MR) imaging. A comment on the classification of these lesions is provided in an effort to clarify the confusing taxonomy surrounding intraspinal cysts. Case Report
This 37-year-old white right-handed male physical education instructor presented with severe neck pain. Four years before admission he had experienced several weeks of occipital headaches following minor trauma to his neck. A subsequent episode of minor trauma resulted in prolonged cervical discomfort without radiation, and a diagnosis of cervical spondylosis was made. The patient experienced three to five exacerbations of his neck pain during each subsequent year. All episodes 788
9 cyst, epithelial
9 cyst, enterogenous
9
of pain subsided with a short course of bed rest, cervical traction, and nonsteroidal anti-inflammatory agents. This presentation represented his most severe exacerbation. Admission. The patient denied radiation of pain beyond the neck and shoulders. He also denied weakness, difficulty with swallowing, changes in his voice, gait problems, and difficulty with bowel, bladder, or sexual function. He reported a brief episode of decreased temperature sensation over the right side of his body (face excluded) which had occurred 4 years previously and had lasted 1 to 2 weeks. He denied any sensory abnormalities at the time of presentation. His medical history was significant for viral meningitis at 4 years old and an episode of Bell's palsy at 21 years of age, both without apparent sequelae. Physical examination revealed a well-developed, stocky individual weighing 98 kg and 183 cm in height. Prominent posterior nuchal spasm with mild limitation of movement in all directions was noted. The hairline was normal. No dysmorphic features or cutaneous lesions were noted~ and the remainder of the general physical examination was normal. The neurological examination demonstrated normal mentation, cranial nerve function, motor strength, and sensation. Mild hyperreflexia of both lower extremities was present. A Babinski response was elicited bilaterally. The gait was normal. Computerized tomography scanning through the posterior fossa revealed a low-density area at the site
J. Neurosurg. / Volume 73/November, 1990
Intradural epithelial cyst
FIG. 1. Sagittal T~-weighted magnetic resonance image demonstrating marked displacement of neural structures by the lesion.
TABLE 1
FIG. 2. Intraoperative photograph illustrating rightward displacement of the spinal cord by the cystic lesion.
Various names under which intradural epithelial cysts have appeared in the literature
archenteric cyst~'9.19 cystic teratoma~9 endodermal cyst6 enteric cyst9 enterogenous cystt' ~8.~9 ependymal cyst9
f o r e g u t c y s t 19 g a s t r o c y t o m a L ~8, ~9
intestinoma~,9
n e u r e n t e r i c cyst 9"19 n e u r o e p i t h e l i a l cyst 7
teratomatous cysf"18
e p i t h e l i a l c y s t 19
normally occupied by the medulla. The cervicomedullary junction was displaced posteriorly and to the right. Lower slices depicted posterior displacement of the upper cervical cord. Magnetic resonance imaging demonstrated a sharply marginated, oval, extra-axial lesion which displaced the medulla and upper cervical cord posteriorly and to the right. On Trweighted images the lesion had a signal intensity lower than that of brain tissue but higher than that of cerebrospinal fluid (Fig. 1). Operation. A suboccipital craniectomy with a C1-2 laminectomy was performed through a midline incision with the patient in the sitting position. The dura was opened in a Y-shaped fashion, revealing a cystic mass with a translucent wall (Fig. 2). The mass was found to J. Neurosurg. / Volume 73/November, 1990
occupy the entire left half of the spinal canal at the C 12 level and to extend through the foramen magnum. It appeared to arise from an anterior position, displacing the cerebellum superiorly and the cord dorsally and to the right. The left nerve roots were distorted and splayed over the mass. Straw-colored fluid was aspirated from the cyst, partially decompressing the lesion. The cyst was then widely fenestrated with approximately 50% to 60% of the wall being excised. Dental mirrors allowed visualization of the anterior surface of the cord. The cyst wall was tightly adherent there and no attempt was made to resect that portion. The dura was closed tightly. Pathological E x a m i n a t i o n . Analysis of the cyst fluid showed a protein content of 1243 mg/dl. No red cells or polymorphonuclear cells were observed; occasional monocytes were noted. Microscopic sections of the cyst revealed a simple cuboidal and columnar nonciliated epithelial lining. The lining cells had basal nuclei with supranuclear vacuoles (Fig. 3). The contents of these vacuoles stained strongly with a mucicarmine stain and a periodic acid-Schiff (PAS) stain, both with and without diastase digestion. A distinct basement membrane separating the epithelium from a delicate fibrovascular stroma was identified by both a silver 789
R. E. Breeze, et al.
FIG. 3. Photomicrograph of the cyst showing columnar epithelial cells with basal nuclei and supranuclear vacuoles. H & E, x 200.
stain (Jones method) and a PAS stain. Immunohistochemical stains revealed that the epithelial lining was keratin-positive and glial fibrillary acidic protein (GFAP)-negative. A diagnosis of enterogeneous cyst was made, based on the presence of tissue representative of a single germ-cell layer, strong mucin staining of the epithelial cells, a distinct basement membrane, and keratin-positive GFAP-negative epithelial cells. Postoperative Course. The postoperative course was uneventful. Neurological examination at 1 month revealed no deficits; the plantar response had returned to normal. An MR image obtained 9 months postoperatively showed no evidence of cyst recurrence. There was no return of symptoms at 1 year. Discussion
There exists a family of presumably congenital, thinwalled, spinal cysts, the members of which are observed usually in the subarachnoid space, although they are occasionally found in an intramedullary or mixed position. Histological examination of the cyst wall most often reveals laminae of mature collagen, with islets of arachnoid cells identifying the lesion as an arachnoid cyst. Rarely, as in the case described here, the cyst is lined by true epithelium. These intradural epithelial cysts can be divided reasonably into two or three fundamentally different types. If the epithelial lining is derived from neuroectodermal tissue, the lesion is most properly called an "ependymal" or "neuroepithelial" cyst. If the lesion arises from misplaced multipotential germinal cells, the term "teratomatous cyst" is applied. If heterotopic intestinal tissue is the presumed origin of the epithelial cells, it is called an "enterogenous cyst." The distinction between these latter two types is controversial. Enterogenous anomalies comprise a spectrum of congenital defects which presumably have a common origin from heterotopic endodermal tissue. In support 790
of this view is the demonstration of keratin and the lack of GFAP in the epithelial lining cells. During embryonic Stage 7 (Days 16 to 17 of gestation), intercalation of the notochord into the entoderm results in the formation of the neurenteric canal, allowing for a temporary communication between the amniotic cavity and yolk sac. This process is followed by excalation as the entoderm separates from the notochordal tissue and mesoderm condenses around the re-formed notochord to form the vertebral column, 8 Many authors suggest that abnormal adhesion between the notochord and endoderm during the 3rd week of embryological development constitutes the common etiological event in the formation of the enterogenous anomalies. The most extreme expression of this group is the so-called "split notochord syndrome. ''2 The opposite end of the spectrum is represented by the intraspinal enterogenous cyst unaccompanied by other abnormalities. Feller and Sternberg 4 classified these enteric and neural malformations into four groups based on the relative positions of the spinal cord, vertebral column, and alimentary canal. Their work was based on a study of 28 cases and dealt mainly with major malformations, some incompatible with life. In cases with a remnant of a dorsal ectoendodermal fistula or associated visceral anomalies, an endodermal origin for the cyst is relatively secure. However, when cysts are found within the spinal canal without associated vertebral, neural, or enteric defects, their origin is less secure. Wilkins and Odom 19 referred to these latter lesions as intraspinal neurenteric cysts, and divided them into three groups. Group A, the simplest, includes cysts lined by a single layer of pseudostratified, stratified cuboidal, or columnar epithelium, with or without cilia, on a basement membrane supported by vascular connective tissue. A significant number of cells will contain mucin, and some goblet cells may be present. If mucous glands, serous glands, muscle, fat, cartilage, bone, ganglion cells, or other elements normally found along the gastrointestinal or tracheobronchial tree are noted, the lesion is classified in Group B. The presence of ependymal or glial tissue places the lesion in Group C. Wilkins and Odom found 47 cases in the literature which fit their description of an intraspinal neurenteric cyst. Twenty-two cases fell into Group A, as does the case presented in this report. Teratomatous cysts presumably arise from multipotential germinal cells. The distinction between an entirely intraspinal enterogenous cyst without associated anomalies and a teratomatous cyst of the spinal cord is not always clear. Rosenbaum, et al., ~8 found 46 cases of primary intraspinal teratomas in the literature. Their search excluded dermoid, epidermoid, and sacrococcygeal teratomatous cysts, but included the so-called "bigerminal teratoma" or "teratoid tumor." They classified 22 of the 46 cases as teratomatous cysts of the spinal canal, and described these cysts as being lined with epithelial cells on a basement membrane of fibrovascular tissue. The epithelial lining varied from a singleJ. Neurosurg. / Volume 73/November, 1990
Intradural epithelial cyst cell layer to multiple cells. Some mucin-producing cells were generally present. This description is remarkably similar to the description by Wilkins and O d o m 19 of an intraspinal neurenteric cyst. Indeed, 19 of the 22 cases of teratomatous cysts reported by Rosenbaum, et al., appear among Wilkins and Odom's 47 cases of intraspinal neurenteric cysts. Rosenbaum, et al., alluded to the possible confusion, but stated that the lack of ciliated epithelium and the abundance of mucin-producing cells and goblet cells should serve to distinguish enterogenous cysts from teratomatous cysts. This distinction may be artificial. Fabinyi and Adams 3 have pointed out that the presence of ciliated epithelium does not exclude an endodermal origin since embryonic esophageal epithelium is ciliated at an early stage of development. Some of the cases c o m m o n to the series of Wilkins and Odom ~9 and Rosenbaum, et al., ~8 have been subjected to studies of sex chromatin. In two of four male patients studied by Hoefnagel, et al., 12 the epithelial cells contained Barr bodies. Among the four male patients studied by Rewcastle and Francoeur, ~7 two possessed epithelial cells with Barr bodies. Cases in which the cytological sex of the lesion differs from the sex of the patient have been cited by some authors as evidence of a true teratomatous origin. Others have discounted this finding, pointing out that primordial germ cells (presumably the only cells that normally contain Barr bodies in a male patient) are initially located in the wall of the yolk sac and subsequently migrate along the dorsal mesentery. Therefore, heterotopic intestinal tissue could conceivably contain Barr bodies depending on when and where it became incorporated into the malformation. A clear distinction between teratomatous cysts and neurenteric cysts awaits a clearer understanding of the pathogenesis of these two lesions. Conclusions
Intradural epithelial cysts are rare lesions. They may be divided into three types based on their presumed pathogenesis: those of an ependymal origin, those of a teratomatous origin, and those of an enterogenous origin. Ependymal cysts are distinguished by the presence of GFAP, the lack of a basement membrane, and little to no glycoprotein or keratin in the cytoplasm of their epithelial cells. The distinction between the latter two groups is confusing at best and may be artificial at our present level of understanding. Regardless of type, these lesions are benign and can be satisfactorily treated with subtotal excision. References
1. Agnoli AL, Laun A, Schrnmayr R: Enterogenous intraspinal cysts. J Neurosurg 61:834-840, 1984 2. Bentley JFR, Smith JR: Developmental posterior enteric
J. Neurosurg. / Volume 7 3 / N o v e m b e r , 1990
3. 4. 5. 6. 7. 8. 9.
10. 11. 12.
13. 14. 15. 16.
17. 18. 19.
remnants and spinal malformations. The split notochord syndrome. Arch Dis Child 35:76-86, 1960 Fabinyi GCA, Adams JE: High cervical spinal cord compression by an enterogenous cyst. Case report. J Neurosurg 51:556-559, 1979 Feller A, Sternberg H: Cited in Reference 19 Findler G, Hadani M, Tadmor R, et al: Spinal intradural ependymal cyst: a case report and review of the literature. Neurosurgery 17:484-486, 1985 Fortuna A, Mercuri S: Intradural spinal cysts. Acta Neurochir 68:289-314, 1983 Fortuna A, Palma L, Mercuri S: Spinal neuroepithelial cysts. Report of two cases and review of the literature. Acta Neurochir 45:177-185, 1978 French BN: The embryology of spinal dysraphism. Clin Neurosurg 30:295-340, 1983 Gimeno A: Arachnoid neurenteric and other cysts, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurology, Voi 32. Congenital Malformations of the Spine and Spinal Cord. Amsterdam: North-Holland, 1978, pp 393-448 Guilburd JN, Arieh YB, Peyser E: Spinal intradural enterogenous cyst: report of a case. Surg Neurol 14: 359-362, 1980 Harriman DGF: An intraspinal enterogenous cyst. J Pathol Bacteriol 75:413-419, 1958 Hoefnagel D, Benirschke K, Duarte J: Teratomatous cysts within the vertebral canal: observations on the occurrence of sex chromatin. J Neurol Neurosurg Psychiatry 25: 159-164, 1962 Holmes GL, Trader S, Ignatiadis P: Intraspinal enterogenous cysts: a case report and review of pediatric cases in the literature. Am J Dis Child 132:906-908, 1978 Kwok DMF, Jeffreys RV: Intramedullary enterogenous cyst of the spinal cord. Case report. J Neurosurg 56: 270-274, 1982 Padovani R, Tognetti F, Laudadio S, et al: Teratoid cyst of the spinal cord. Neurosurgery 13:74-77, 1983 Palma L, DiLorenzo N: Spinal endodermal cysts without associated vertebral or other congenital abnormalities. Report of four cases and review of the literature. Acta Neurochir 33:283-300, 1976 Rewcastle NB, Francoeur J: Teratomatous cyst of the spinal canal, with "sex chromatin" studies. Arch Neuroi 11:91-99, 1964 Rosenbaum TJ, Soule EH, Onofrio BM: Teratomatous cyst of the spinal canal. Case report. J Neurosurg 49: 292-297, 1978 Wilkins RH, Odom GL: Spinal intradural cysts, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurology, Vol 20. Tumors of the Spine and Spinal Cord, Part II. Amsterdam: North-Holland, 1976, pp 55-102
Manuscript received July 17, 1987. Accepted in final form April 10, 1990. Address for Drs. Nichols, Segal, and Apuzzo: University of Southern California School of Medicine, Los Angeles, California. Address reprint requests to: Robert E. Breeze, M.D., Department of Surgqry (Neurosurgery), University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Campus Box C-307, Denver, Colorado 80262.
791
Intradural epithelial cyst at the craniovertebral junction Case report ROBERT E. BREEZE, M.D., PETER NICHOLS, M.D., HERVEY SEGAL, M.D., AND MICHAEL L. J. A e u z z o , M.D.
Division of Neurosurgery, University of Colorado Health Sciences Center, Denver, Colorado; and Departments of Pathology, Radiology (Neuroradiology), and Neurological Surgery, University of Southern California School of Medicine, Los Angeles, California o- A case of an intradural epithelial cyst at the craniovertebral junction is reported in a 37-year-old man. The classification of these rare lesions is discussed. KEY WORDS 9 cyst, intradural craniovertebral junction
T
HE term "intradural epithelial cyst" is used in this report to identify those lesions commonly referred to as "ependymal cysts," "enterogenous cysts," and "teratomatous cysts." Excluded from discussion are epidermoid and dermoid cysts, solid teratomas, and colloid cysts; although these lesions may be found in the spinal canal and contain epithelial tissue, they are easily distinguished from the much rarer thinwalled fluid-filled cysts, herein called "intradural epithelial cysts." Seventy-seven intradural epithelial cysts have been reported in the literature under different terms (Table 1). 1,3,5-7,9-11,13-16,18,19 This communication describes the first reported case of an enterogenous cyst at the craniovertebral junction and the first intradural epithelial cyst to be identified by magnetic resonance (MR) imaging. A comment on the classification of these lesions is provided in an effort to clarify the confusing taxonomy surrounding intraspinal cysts. Case Report
This 37-year-old white right-handed male physical education instructor presented with severe neck pain. Four years before admission he had experienced several weeks of occipital headaches following minor trauma to his neck. A subsequent episode of minor trauma resulted in prolonged cervical discomfort without radiation, and a diagnosis of cervical spondylosis was made. The patient experienced three to five exacerbations of his neck pain during each subsequent year. All episodes 788
9 cyst, epithelial
9 cyst, enterogenous
9
of pain subsided with a short course of bed rest, cervical traction, and nonsteroidal anti-inflammatory agents. This presentation represented his most severe exacerbation. Admission. The patient denied radiation of pain beyond the neck and shoulders. He also denied weakness, difficulty with swallowing, changes in his voice, gait problems, and difficulty with bowel, bladder, or sexual function. He reported a brief episode of decreased temperature sensation over the right side of his body (face excluded) which had occurred 4 years previously and had lasted 1 to 2 weeks. He denied any sensory abnormalities at the time of presentation. His medical history was significant for viral meningitis at 4 years old and an episode of Bell's palsy at 21 years of age, both without apparent sequelae. Physical examination revealed a well-developed, stocky individual weighing 98 kg and 183 cm in height. Prominent posterior nuchal spasm with mild limitation of movement in all directions was noted. The hairline was normal. No dysmorphic features or cutaneous lesions were noted~ and the remainder of the general physical examination was normal. The neurological examination demonstrated normal mentation, cranial nerve function, motor strength, and sensation. Mild hyperreflexia of both lower extremities was present. A Babinski response was elicited bilaterally. The gait was normal. Computerized tomography scanning through the posterior fossa revealed a low-density area at the site
J. Neurosurg. / Volume 73/November, 1990
Intradural epithelial cyst
FIG. 1. Sagittal T~-weighted magnetic resonance image demonstrating marked displacement of neural structures by the lesion.
TABLE 1
FIG. 2. Intraoperative photograph illustrating rightward displacement of the spinal cord by the cystic lesion.
Various names under which intradural epithelial cysts have appeared in the literature
archenteric cyst~'9.19 cystic teratoma~9 endodermal cyst6 enteric cyst9 enterogenous cystt' ~8.~9 ependymal cyst9
f o r e g u t c y s t 19 g a s t r o c y t o m a L ~8, ~9
intestinoma~,9
n e u r e n t e r i c cyst 9"19 n e u r o e p i t h e l i a l cyst 7
teratomatous cysf"18
e p i t h e l i a l c y s t 19
normally occupied by the medulla. The cervicomedullary junction was displaced posteriorly and to the right. Lower slices depicted posterior displacement of the upper cervical cord. Magnetic resonance imaging demonstrated a sharply marginated, oval, extra-axial lesion which displaced the medulla and upper cervical cord posteriorly and to the right. On Trweighted images the lesion had a signal intensity lower than that of brain tissue but higher than that of cerebrospinal fluid (Fig. 1). Operation. A suboccipital craniectomy with a C1-2 laminectomy was performed through a midline incision with the patient in the sitting position. The dura was opened in a Y-shaped fashion, revealing a cystic mass with a translucent wall (Fig. 2). The mass was found to J. Neurosurg. / Volume 73/November, 1990
occupy the entire left half of the spinal canal at the C 12 level and to extend through the foramen magnum. It appeared to arise from an anterior position, displacing the cerebellum superiorly and the cord dorsally and to the right. The left nerve roots were distorted and splayed over the mass. Straw-colored fluid was aspirated from the cyst, partially decompressing the lesion. The cyst was then widely fenestrated with approximately 50% to 60% of the wall being excised. Dental mirrors allowed visualization of the anterior surface of the cord. The cyst wall was tightly adherent there and no attempt was made to resect that portion. The dura was closed tightly. Pathological E x a m i n a t i o n . Analysis of the cyst fluid showed a protein content of 1243 mg/dl. No red cells or polymorphonuclear cells were observed; occasional monocytes were noted. Microscopic sections of the cyst revealed a simple cuboidal and columnar nonciliated epithelial lining. The lining cells had basal nuclei with supranuclear vacuoles (Fig. 3). The contents of these vacuoles stained strongly with a mucicarmine stain and a periodic acid-Schiff (PAS) stain, both with and without diastase digestion. A distinct basement membrane separating the epithelium from a delicate fibrovascular stroma was identified by both a silver 789
R. E. Breeze, et al.
FIG. 3. Photomicrograph of the cyst showing columnar epithelial cells with basal nuclei and supranuclear vacuoles. H & E, x 200.
stain (Jones method) and a PAS stain. Immunohistochemical stains revealed that the epithelial lining was keratin-positive and glial fibrillary acidic protein (GFAP)-negative. A diagnosis of enterogeneous cyst was made, based on the presence of tissue representative of a single germ-cell layer, strong mucin staining of the epithelial cells, a distinct basement membrane, and keratin-positive GFAP-negative epithelial cells. Postoperative Course. The postoperative course was uneventful. Neurological examination at 1 month revealed no deficits; the plantar response had returned to normal. An MR image obtained 9 months postoperatively showed no evidence of cyst recurrence. There was no return of symptoms at 1 year. Discussion
There exists a family of presumably congenital, thinwalled, spinal cysts, the members of which are observed usually in the subarachnoid space, although they are occasionally found in an intramedullary or mixed position. Histological examination of the cyst wall most often reveals laminae of mature collagen, with islets of arachnoid cells identifying the lesion as an arachnoid cyst. Rarely, as in the case described here, the cyst is lined by true epithelium. These intradural epithelial cysts can be divided reasonably into two or three fundamentally different types. If the epithelial lining is derived from neuroectodermal tissue, the lesion is most properly called an "ependymal" or "neuroepithelial" cyst. If the lesion arises from misplaced multipotential germinal cells, the term "teratomatous cyst" is applied. If heterotopic intestinal tissue is the presumed origin of the epithelial cells, it is called an "enterogenous cyst." The distinction between these latter two types is controversial. Enterogenous anomalies comprise a spectrum of congenital defects which presumably have a common origin from heterotopic endodermal tissue. In support 790
of this view is the demonstration of keratin and the lack of GFAP in the epithelial lining cells. During embryonic Stage 7 (Days 16 to 17 of gestation), intercalation of the notochord into the entoderm results in the formation of the neurenteric canal, allowing for a temporary communication between the amniotic cavity and yolk sac. This process is followed by excalation as the entoderm separates from the notochordal tissue and mesoderm condenses around the re-formed notochord to form the vertebral column, 8 Many authors suggest that abnormal adhesion between the notochord and endoderm during the 3rd week of embryological development constitutes the common etiological event in the formation of the enterogenous anomalies. The most extreme expression of this group is the so-called "split notochord syndrome. ''2 The opposite end of the spectrum is represented by the intraspinal enterogenous cyst unaccompanied by other abnormalities. Feller and Sternberg 4 classified these enteric and neural malformations into four groups based on the relative positions of the spinal cord, vertebral column, and alimentary canal. Their work was based on a study of 28 cases and dealt mainly with major malformations, some incompatible with life. In cases with a remnant of a dorsal ectoendodermal fistula or associated visceral anomalies, an endodermal origin for the cyst is relatively secure. However, when cysts are found within the spinal canal without associated vertebral, neural, or enteric defects, their origin is less secure. Wilkins and Odom 19 referred to these latter lesions as intraspinal neurenteric cysts, and divided them into three groups. Group A, the simplest, includes cysts lined by a single layer of pseudostratified, stratified cuboidal, or columnar epithelium, with or without cilia, on a basement membrane supported by vascular connective tissue. A significant number of cells will contain mucin, and some goblet cells may be present. If mucous glands, serous glands, muscle, fat, cartilage, bone, ganglion cells, or other elements normally found along the gastrointestinal or tracheobronchial tree are noted, the lesion is classified in Group B. The presence of ependymal or glial tissue places the lesion in Group C. Wilkins and Odom found 47 cases in the literature which fit their description of an intraspinal neurenteric cyst. Twenty-two cases fell into Group A, as does the case presented in this report. Teratomatous cysts presumably arise from multipotential germinal cells. The distinction between an entirely intraspinal enterogenous cyst without associated anomalies and a teratomatous cyst of the spinal cord is not always clear. Rosenbaum, et al., ~8 found 46 cases of primary intraspinal teratomas in the literature. Their search excluded dermoid, epidermoid, and sacrococcygeal teratomatous cysts, but included the so-called "bigerminal teratoma" or "teratoid tumor." They classified 22 of the 46 cases as teratomatous cysts of the spinal canal, and described these cysts as being lined with epithelial cells on a basement membrane of fibrovascular tissue. The epithelial lining varied from a singleJ. Neurosurg. / Volume 73/November, 1990
Intradural epithelial cyst cell layer to multiple cells. Some mucin-producing cells were generally present. This description is remarkably similar to the description by Wilkins and O d o m 19 of an intraspinal neurenteric cyst. Indeed, 19 of the 22 cases of teratomatous cysts reported by Rosenbaum, et al., appear among Wilkins and Odom's 47 cases of intraspinal neurenteric cysts. Rosenbaum, et al., alluded to the possible confusion, but stated that the lack of ciliated epithelium and the abundance of mucin-producing cells and goblet cells should serve to distinguish enterogenous cysts from teratomatous cysts. This distinction may be artificial. Fabinyi and Adams 3 have pointed out that the presence of ciliated epithelium does not exclude an endodermal origin since embryonic esophageal epithelium is ciliated at an early stage of development. Some of the cases c o m m o n to the series of Wilkins and Odom ~9 and Rosenbaum, et al., ~8 have been subjected to studies of sex chromatin. In two of four male patients studied by Hoefnagel, et al., 12 the epithelial cells contained Barr bodies. Among the four male patients studied by Rewcastle and Francoeur, ~7 two possessed epithelial cells with Barr bodies. Cases in which the cytological sex of the lesion differs from the sex of the patient have been cited by some authors as evidence of a true teratomatous origin. Others have discounted this finding, pointing out that primordial germ cells (presumably the only cells that normally contain Barr bodies in a male patient) are initially located in the wall of the yolk sac and subsequently migrate along the dorsal mesentery. Therefore, heterotopic intestinal tissue could conceivably contain Barr bodies depending on when and where it became incorporated into the malformation. A clear distinction between teratomatous cysts and neurenteric cysts awaits a clearer understanding of the pathogenesis of these two lesions. Conclusions
Intradural epithelial cysts are rare lesions. They may be divided into three types based on their presumed pathogenesis: those of an ependymal origin, those of a teratomatous origin, and those of an enterogenous origin. Ependymal cysts are distinguished by the presence of GFAP, the lack of a basement membrane, and little to no glycoprotein or keratin in the cytoplasm of their epithelial cells. The distinction between the latter two groups is confusing at best and may be artificial at our present level of understanding. Regardless of type, these lesions are benign and can be satisfactorily treated with subtotal excision. References
1. Agnoli AL, Laun A, Schrnmayr R: Enterogenous intraspinal cysts. J Neurosurg 61:834-840, 1984 2. Bentley JFR, Smith JR: Developmental posterior enteric
J. Neurosurg. / Volume 7 3 / N o v e m b e r , 1990
3. 4. 5. 6. 7. 8. 9.
10. 11. 12.
13. 14. 15. 16.
17. 18. 19.
remnants and spinal malformations. The split notochord syndrome. Arch Dis Child 35:76-86, 1960 Fabinyi GCA, Adams JE: High cervical spinal cord compression by an enterogenous cyst. Case report. J Neurosurg 51:556-559, 1979 Feller A, Sternberg H: Cited in Reference 19 Findler G, Hadani M, Tadmor R, et al: Spinal intradural ependymal cyst: a case report and review of the literature. Neurosurgery 17:484-486, 1985 Fortuna A, Mercuri S: Intradural spinal cysts. Acta Neurochir 68:289-314, 1983 Fortuna A, Palma L, Mercuri S: Spinal neuroepithelial cysts. Report of two cases and review of the literature. Acta Neurochir 45:177-185, 1978 French BN: The embryology of spinal dysraphism. Clin Neurosurg 30:295-340, 1983 Gimeno A: Arachnoid neurenteric and other cysts, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurology, Voi 32. Congenital Malformations of the Spine and Spinal Cord. Amsterdam: North-Holland, 1978, pp 393-448 Guilburd JN, Arieh YB, Peyser E: Spinal intradural enterogenous cyst: report of a case. Surg Neurol 14: 359-362, 1980 Harriman DGF: An intraspinal enterogenous cyst. J Pathol Bacteriol 75:413-419, 1958 Hoefnagel D, Benirschke K, Duarte J: Teratomatous cysts within the vertebral canal: observations on the occurrence of sex chromatin. J Neurol Neurosurg Psychiatry 25: 159-164, 1962 Holmes GL, Trader S, Ignatiadis P: Intraspinal enterogenous cysts: a case report and review of pediatric cases in the literature. Am J Dis Child 132:906-908, 1978 Kwok DMF, Jeffreys RV: Intramedullary enterogenous cyst of the spinal cord. Case report. J Neurosurg 56: 270-274, 1982 Padovani R, Tognetti F, Laudadio S, et al: Teratoid cyst of the spinal cord. Neurosurgery 13:74-77, 1983 Palma L, DiLorenzo N: Spinal endodermal cysts without associated vertebral or other congenital abnormalities. Report of four cases and review of the literature. Acta Neurochir 33:283-300, 1976 Rewcastle NB, Francoeur J: Teratomatous cyst of the spinal canal, with "sex chromatin" studies. Arch Neuroi 11:91-99, 1964 Rosenbaum TJ, Soule EH, Onofrio BM: Teratomatous cyst of the spinal canal. Case report. J Neurosurg 49: 292-297, 1978 Wilkins RH, Odom GL: Spinal intradural cysts, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurology, Vol 20. Tumors of the Spine and Spinal Cord, Part II. Amsterdam: North-Holland, 1976, pp 55-102
Manuscript received July 17, 1987. Accepted in final form April 10, 1990. Address for Drs. Nichols, Segal, and Apuzzo: University of Southern California School of Medicine, Los Angeles, California. Address reprint requests to: Robert E. Breeze, M.D., Department of Surgqry (Neurosurgery), University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Campus Box C-307, Denver, Colorado 80262.
791
