J Neurosurg 48:475-478, 1978
Intradiploic epidermoid cyst of the occipital bone with torcular obstruction Case report
SETTI RENGACHARY, M.D., PULLA R. S. KISHORE, M.D., AND ITARU W A T A N A B E , M.D. Neurosurgery and Laboratory Services, Veterans Administration Hospital, Kansas City, Missouri, and Departments of Surgery, Diagnostic Radiology and Pathology, University of Kansas Medical Center, Kansas City, Kansas
v' The authors describe a patient with a giant occipital intradiploic epidermoid cyst with compression of the torcular and other posterior fossa structures. KEY WORDS
9
epidermoid cyst
NTRADIPLOIC epidermoid cyst is a benign epithelial lesion that is commonly seen as an incidental finding on radiographic examination of the skull. A palpable bony lump may be present overlying the cyst. Infrequently the cyst may erode through the inner table and may compress the intracranial structures. Because of the slow expansion of the cyst, the neurological deficit is usually minimal. Recently a patient presented with a giant intradiploic epidermoid cyst of the occipital bone causing angiographically demonstrated occlusion of the torcular herophili and the adjacent major venous sinuses with compression of the brain stem. Failure to find an analogous case in the literature prompted this case report; in addition, the cyst reported here appears to be the largest intradiploic epidermoid cyst on record. 1,4
I
Case Report This 62-year-old man suffered a cerebrovascular accident in November, 1971, J. Neurosurg. / Volume 48 / March, 1978
9 torcular herophili
resulting in left hemiplegia, hemianesthesia, and homonymous hemianopsia. Carotid angiography showed total occlusion of the internal carotid artery on the right side. Incidentally, a benign intradiploic mass measuring 9 cm across, was noted in the occipital bone. Because of fresh massive cerebral infarction and absence of symptoms referable to the mass, no surgery was undertaken. Four years later, in October, 1975, the patient was admitted with progressively increasing headaches, nausea, and vomiting with intermittent choking spells and nocturnal stridor. Examination. He was globally demented with loss of orientation in all three spheres. There was no papilledema. The sensory, motor, and visual deficits noted in 1971 had remained unchanged. X-Ray film of the skull (Fig. 1) revealed a lytic lesion involving nearly the entire occipital bone extending from the region of the lambdoidal suture to the foramen magnum. The lesion was intradiploic with expansion and thinning of both the inner and outer tables. It measured 13 cm 475
S. Rengachary, P. R. S. Kishore and I. Watanabe present posteriorly occupying most of the posterior cranial fossa. A rim of contrast enhancement appeared on the post infusion scans anteriorly and superiorly, separating the lesion from the adjacent brain. Moderately severe hydrocephalus was present involving the lateral and third ventricles with distortion of the fourth ventricle. Bilateral carotid and vertebral angiography (Fig. 3) revealed obliteration of the superior sagittal sinus precisely at the superior margin of the bony lesion, with non-opacification of the torcular. Collateral venous drainage was FIG. 1. X-ray film of the skull showingthe lytic demonstrated through the convexity veins via lesion (arrows) involving nearly the entire occipital the inferior anastomotic vein of Labb6 into the lateral part of the transverse and sigmoid bone. sinuses. The findings on isotope angiography closely paralleled those of carotid angiography. The proximal superior sagittal in maximum diameter, and presented a sinus and the sigmoid sinuses showed normal scalloped, sclerotic outline. activity, but the intervening transverse Computerized tomography (CT) scan (Fig. sinuses, the torcular region, and the distal 2) revealed a porencephalic cyst occupying sagittal sinus showed no activity. the right frontoparietotemporal areas in the Operation. Through a posterior vertical region of previous infarct. Additionally, a midline incision, the occipital bone was exlarge well circumscribed cystic lesion was posed. Several areas of the bone were found to be eggshell thin and could be easily indented. On removing the thinned-out outer table of the skull, semisolid cheesy material was encountered to a depth of 5 cm. The inner table of the bone appeared nearly totally destroyed, exposing the dura covering the occipital poles, the collapsed transverse sinuses, the torcular, the cerebellar hemispheres, and the lower brain stem. The dura was noted to be intact throughout. Total removal of the cyst and its contents was accomplished. The major venous sinuses, however, did not appear to refill after cyst removal. Pathological Examination. The cyst wall consisted of a layer of connective tissue lined by stratified squamous epithelium consistent with a diagnosis of epidermoid cyst. There were no dermal elements present. Postoperative Course. In the immediate postoperative period, the headaches, nausea, vomiting, and the episodes of stridor cleared. Over the ensuing month, dementia and disorientation improved and essentially reached the premorbid level. The only deficits noted on follow-up examination 1 year later were FIG. 2. Computerized tomography scan show- the left hemiplegia, hemianesthesia, and ing the large cystic lesion occupying almost all of the posterior cranial fossa (arrows). Note also the hemianopsia secondary to the completed large porencephalic cyst communicating with the stroke suffered 5 years earlier. A recent CT ventricle in the right frontal area. scan showed a decrease in the ventricular size
476
J. Neurosurg. / Volume 48 / March, 1978
Occipital epidermoid cyst with torcular obstruction
FIG. 3. Carotid arteriogram in the venous phase. Left: Anteroposterior view showing occlusion of the superior sagittal sinus at the margin of the bony defect (arrow). Right: Lateral view showing the collateral flow along the convexity veins (small arrows) into the vein of Labb6 (open arrows) and the sigmoid sinus (large arrow). to nearly normal appearance, but the porencephalic cyst remained unchanged. Discussion
The signs of increased intracranial pressure noted in this patient appear to be due to a combination of two factors. One is the direct compression of the fourth ventricle and possible kinking of the aqueduct by the mass with the resultant obstructive hydrocephalus demonstrated on the CT scan; the other is occlusion of the major venous sinuses with resulting venous congestion. The latter may not be as important because collateral venous circulation appeared adequate. In addition to the above, the headaches may have been caused by direct pressure by the mass on a large segment of the dura which is known to be sensitive to pain. Obstructive hydrocephalus also explains the global dementia and disorientation which reversed on removal of the mass. The choking spells and the stridor were probably due to pressure on the lower brain stem, although objective paralysis of pharyngeal or laryngeal muscles were not noted on clinical examination. Epidermoid cysts may occur in the scalp, within the diploe, 4,8 in the intracranial
J. Neurosurg. / Volume 48 / March, 1978
cavity3'~ or in the spinal canal. 6 They constitute approximately 1% of all intracranial tumors. Although the majority of epidermoid tumors are benign, at least five instances of malignant degeneration have been recorded. 2'4'5 The intradiploic cysts may occur in any flat calvarial bone, about evenly distributed in the frontal, parietal, temporal, and occipital bones roughly proportionate to their surface area. Multiple cysts around the neuroaxis have been recorded. Epidermoid cysts occur because of sequestration of ectodermal elements. This may be congenital or acquired. Congenital sequestration occurs between the third and fifth weeks of intrauterine life as the medullary groove closes. Sequestration usually occurs either in midline or in relation to optic and otic vesicles) The acquired causes for epidermoid cysts include multiple spinal taps or improper approximation of a surgical incision with mechanical implantation of epidermal tissue into the deeper tissue. Recent experimental evidence substantiates the latter mechanism.i~ References
I. Cushing H: A large epidermal cholesteatoma of the parietotemporal region deforming the
477
S. Rengachary, P. R. S. Kishore and I. Watanabe
2. 3. 4.
5.
6. 7.
478
left hemisphere without cerebral symptoms. Surg Gyneeol Obstet 34:557-566, 1922 Davidson SI, Small JM: Malignant change in an intracranial epidermoid. J Neurol Neurosurg Psychiatr 23:176-178, 1960 Fleming JFR, Botterell EH: Cranial dermoid and epidermoid tumors. Surg Gyneeol Obstet 109:403-41 l, 1959 Haig PV: Primary epidermoids of the skull, including a case with malignant change. Am J Roentgenol Radium Ther Nuel Med 76: 1076-1080, 1956 Landers JW, Danielski J J: Malignant intracranial epidermoid cyst. Report of a case with leptomeningeal spread. Arch Pathol 70: 419-423, 1960 Manno N J, Uihlein A, Kernohan JW: Intraspinal epidermoids. J Neurosurg 19:754765, 1962 Reeves DL: Epidermoid (mixed) tumors of the
central nervous system. J Neurosurg 26:21-24, 1967 8. Skandalakis JE, Godwin JT, Mabon RF: Epidermoid cyst of the skull. Surgery 43: 990-1001, 1958 9. Toglia JU, Netsky MG, Alexander E Jr: Epithelial (epidermoid) tumors of the cranium. Their common nature and pathogenesis. J Neurosurg 23:384-393, 1965 10. Van Gilder JC, Schwartz HG: Growth of dermoids from skin implants to the nervous system and surrounding spaces of the newborn rat. J Neurosurg 26:14-20, 1967
Address reprint requests to: Setti Rengachary, M.D., Neurosurgery Service, Veterans Administration Hospital, 4801 Linwood Boulevard, Kansas City, Missouri 64128.
J. Neurosurg. / Volume 48 / March, 1978
Intradiploic epidermoid cyst of the occipital bone with torcular obstruction Case report
SETTI RENGACHARY, M.D., PULLA R. S. KISHORE, M.D., AND ITARU W A T A N A B E , M.D. Neurosurgery and Laboratory Services, Veterans Administration Hospital, Kansas City, Missouri, and Departments of Surgery, Diagnostic Radiology and Pathology, University of Kansas Medical Center, Kansas City, Kansas
v' The authors describe a patient with a giant occipital intradiploic epidermoid cyst with compression of the torcular and other posterior fossa structures. KEY WORDS
9
epidermoid cyst
NTRADIPLOIC epidermoid cyst is a benign epithelial lesion that is commonly seen as an incidental finding on radiographic examination of the skull. A palpable bony lump may be present overlying the cyst. Infrequently the cyst may erode through the inner table and may compress the intracranial structures. Because of the slow expansion of the cyst, the neurological deficit is usually minimal. Recently a patient presented with a giant intradiploic epidermoid cyst of the occipital bone causing angiographically demonstrated occlusion of the torcular herophili and the adjacent major venous sinuses with compression of the brain stem. Failure to find an analogous case in the literature prompted this case report; in addition, the cyst reported here appears to be the largest intradiploic epidermoid cyst on record. 1,4
I
Case Report This 62-year-old man suffered a cerebrovascular accident in November, 1971, J. Neurosurg. / Volume 48 / March, 1978
9 torcular herophili
resulting in left hemiplegia, hemianesthesia, and homonymous hemianopsia. Carotid angiography showed total occlusion of the internal carotid artery on the right side. Incidentally, a benign intradiploic mass measuring 9 cm across, was noted in the occipital bone. Because of fresh massive cerebral infarction and absence of symptoms referable to the mass, no surgery was undertaken. Four years later, in October, 1975, the patient was admitted with progressively increasing headaches, nausea, and vomiting with intermittent choking spells and nocturnal stridor. Examination. He was globally demented with loss of orientation in all three spheres. There was no papilledema. The sensory, motor, and visual deficits noted in 1971 had remained unchanged. X-Ray film of the skull (Fig. 1) revealed a lytic lesion involving nearly the entire occipital bone extending from the region of the lambdoidal suture to the foramen magnum. The lesion was intradiploic with expansion and thinning of both the inner and outer tables. It measured 13 cm 475
S. Rengachary, P. R. S. Kishore and I. Watanabe present posteriorly occupying most of the posterior cranial fossa. A rim of contrast enhancement appeared on the post infusion scans anteriorly and superiorly, separating the lesion from the adjacent brain. Moderately severe hydrocephalus was present involving the lateral and third ventricles with distortion of the fourth ventricle. Bilateral carotid and vertebral angiography (Fig. 3) revealed obliteration of the superior sagittal sinus precisely at the superior margin of the bony lesion, with non-opacification of the torcular. Collateral venous drainage was FIG. 1. X-ray film of the skull showingthe lytic demonstrated through the convexity veins via lesion (arrows) involving nearly the entire occipital the inferior anastomotic vein of Labb6 into the lateral part of the transverse and sigmoid bone. sinuses. The findings on isotope angiography closely paralleled those of carotid angiography. The proximal superior sagittal in maximum diameter, and presented a sinus and the sigmoid sinuses showed normal scalloped, sclerotic outline. activity, but the intervening transverse Computerized tomography (CT) scan (Fig. sinuses, the torcular region, and the distal 2) revealed a porencephalic cyst occupying sagittal sinus showed no activity. the right frontoparietotemporal areas in the Operation. Through a posterior vertical region of previous infarct. Additionally, a midline incision, the occipital bone was exlarge well circumscribed cystic lesion was posed. Several areas of the bone were found to be eggshell thin and could be easily indented. On removing the thinned-out outer table of the skull, semisolid cheesy material was encountered to a depth of 5 cm. The inner table of the bone appeared nearly totally destroyed, exposing the dura covering the occipital poles, the collapsed transverse sinuses, the torcular, the cerebellar hemispheres, and the lower brain stem. The dura was noted to be intact throughout. Total removal of the cyst and its contents was accomplished. The major venous sinuses, however, did not appear to refill after cyst removal. Pathological Examination. The cyst wall consisted of a layer of connective tissue lined by stratified squamous epithelium consistent with a diagnosis of epidermoid cyst. There were no dermal elements present. Postoperative Course. In the immediate postoperative period, the headaches, nausea, vomiting, and the episodes of stridor cleared. Over the ensuing month, dementia and disorientation improved and essentially reached the premorbid level. The only deficits noted on follow-up examination 1 year later were FIG. 2. Computerized tomography scan show- the left hemiplegia, hemianesthesia, and ing the large cystic lesion occupying almost all of the posterior cranial fossa (arrows). Note also the hemianopsia secondary to the completed large porencephalic cyst communicating with the stroke suffered 5 years earlier. A recent CT ventricle in the right frontal area. scan showed a decrease in the ventricular size
476
J. Neurosurg. / Volume 48 / March, 1978
Occipital epidermoid cyst with torcular obstruction
FIG. 3. Carotid arteriogram in the venous phase. Left: Anteroposterior view showing occlusion of the superior sagittal sinus at the margin of the bony defect (arrow). Right: Lateral view showing the collateral flow along the convexity veins (small arrows) into the vein of Labb6 (open arrows) and the sigmoid sinus (large arrow). to nearly normal appearance, but the porencephalic cyst remained unchanged. Discussion
The signs of increased intracranial pressure noted in this patient appear to be due to a combination of two factors. One is the direct compression of the fourth ventricle and possible kinking of the aqueduct by the mass with the resultant obstructive hydrocephalus demonstrated on the CT scan; the other is occlusion of the major venous sinuses with resulting venous congestion. The latter may not be as important because collateral venous circulation appeared adequate. In addition to the above, the headaches may have been caused by direct pressure by the mass on a large segment of the dura which is known to be sensitive to pain. Obstructive hydrocephalus also explains the global dementia and disorientation which reversed on removal of the mass. The choking spells and the stridor were probably due to pressure on the lower brain stem, although objective paralysis of pharyngeal or laryngeal muscles were not noted on clinical examination. Epidermoid cysts may occur in the scalp, within the diploe, 4,8 in the intracranial
J. Neurosurg. / Volume 48 / March, 1978
cavity3'~ or in the spinal canal. 6 They constitute approximately 1% of all intracranial tumors. Although the majority of epidermoid tumors are benign, at least five instances of malignant degeneration have been recorded. 2'4'5 The intradiploic cysts may occur in any flat calvarial bone, about evenly distributed in the frontal, parietal, temporal, and occipital bones roughly proportionate to their surface area. Multiple cysts around the neuroaxis have been recorded. Epidermoid cysts occur because of sequestration of ectodermal elements. This may be congenital or acquired. Congenital sequestration occurs between the third and fifth weeks of intrauterine life as the medullary groove closes. Sequestration usually occurs either in midline or in relation to optic and otic vesicles) The acquired causes for epidermoid cysts include multiple spinal taps or improper approximation of a surgical incision with mechanical implantation of epidermal tissue into the deeper tissue. Recent experimental evidence substantiates the latter mechanism.i~ References
I. Cushing H: A large epidermal cholesteatoma of the parietotemporal region deforming the
477
S. Rengachary, P. R. S. Kishore and I. Watanabe
2. 3. 4.
5.
6. 7.
478
left hemisphere without cerebral symptoms. Surg Gyneeol Obstet 34:557-566, 1922 Davidson SI, Small JM: Malignant change in an intracranial epidermoid. J Neurol Neurosurg Psychiatr 23:176-178, 1960 Fleming JFR, Botterell EH: Cranial dermoid and epidermoid tumors. Surg Gyneeol Obstet 109:403-41 l, 1959 Haig PV: Primary epidermoids of the skull, including a case with malignant change. Am J Roentgenol Radium Ther Nuel Med 76: 1076-1080, 1956 Landers JW, Danielski J J: Malignant intracranial epidermoid cyst. Report of a case with leptomeningeal spread. Arch Pathol 70: 419-423, 1960 Manno N J, Uihlein A, Kernohan JW: Intraspinal epidermoids. J Neurosurg 19:754765, 1962 Reeves DL: Epidermoid (mixed) tumors of the
central nervous system. J Neurosurg 26:21-24, 1967 8. Skandalakis JE, Godwin JT, Mabon RF: Epidermoid cyst of the skull. Surgery 43: 990-1001, 1958 9. Toglia JU, Netsky MG, Alexander E Jr: Epithelial (epidermoid) tumors of the cranium. Their common nature and pathogenesis. J Neurosurg 23:384-393, 1965 10. Van Gilder JC, Schwartz HG: Growth of dermoids from skin implants to the nervous system and surrounding spaces of the newborn rat. J Neurosurg 26:14-20, 1967
Address reprint requests to: Setti Rengachary, M.D., Neurosurgery Service, Veterans Administration Hospital, 4801 Linwood Boulevard, Kansas City, Missouri 64128.
J. Neurosurg. / Volume 48 / March, 1978
