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Cystic meningiomas
ELSEVIER
Featured Subject: Management of Brain Tumors
CYSTIC MENINGIOMAS K. Sridhar, D.N.B. (Neurosurgery), and M.C. Vasudevan, M.D.
R. Ravi, M.S., B. Ramamurthi,
M.S.,
A. Lakshmipathi Neurosurgical Centre, Voluntary Health Services Medical Centre, Madras, India
Sridhar giomas.
K, Ravi R, Ramamurthi B, Vasudevan Surg Neural 1995;43:235-9.
MC. Cystic
menin-
BACKGROUND
Meningiomas are generally solid tumors and are easily diagnosed by CT scans and MRf scans. Rarely are these tumors associated with cysts that can cause a confusion in the pre- and intraoperative diagnosis. Cysts associated with meningiomas may be intratumoral or peritumoral. METHODS
with meningiomas
is between
4% and 7% [3,12,15].
Even though it is easier to recognize cysts with modern imaging techniques, the differentiation of cystic meningiomas from other cystic tumors of the brain is difficult. The authors present their experience with 17 cases of cystic meningiomas.
MATERIALSANDMETHODS
The authors conducted a retrospective study of the seventeen meningiomas, out of a total number of 232, which were associated with cysts. The cysts were classified based on their relationship to the tumor. The patients’ sex, age group, location of the tumor, and pathological type of tumor were also analyzed. RESULTS The 17 cases of cystic meningioma formed 7.3% of the meningiomas seen between 1984 and 1993. Eleven of these were intratumoral and 6 peritumoral. One case had both intra- and peritumoral cysts. The tumors were found mostly in the fourth and fifth decades of life. Histologically, all the peritumoral cysts except one were associated with meningotheliomatous meningiomas. Tumors with peritumoral cysts were more common in males. lntratumoral cysts, more common in females, were angioblastic or meningotheliomatous on histopathology. Only one case was an anaplastic meningioma.
A retrospective study was undertaken of 232 cases of intracranial meningioma operated between 1984 and 1993 at the Dr. Achanta Lakshmipathi Neurosurgical Centre, Madras. Of these meningiomas, 17 were found to be associated with cysts. The relationship of the cysts to the tumors was analyzed. The cysts were classified into intratumoral and peritumoral cysts based on their relationship to the tumor, and also according to the types as described by Nauta et al [ 121. The patients’ sex, age group, the location of the tumor, and the pathologic type of tumor were also analyzed.
CONCLUSION
RESULTS
Cysts associated with meningiomas, although uncommon, are certainly not rare. The peritumoral and the intratumoral cysts form distinct subtypes needing separate consideration. Cystic meningiomas are only rarely malignant. KEY WORDS
Cyst, intratumoral, meningioma,
peritumoral.
M
eningiomas are generally known to be solid tumors and their classical appearance on the computed tomography (CT) scan and magnetic resonance imaging (MRI) usually leads to a correct diagnosis. Cysts associated with meningiomas are uncommon. The incidence of cysts in association Address reprint requests to: K. Sridhar, M.D., A. Lakshmipathi Neurosurgical Centre, Voluntary Health Services Medical Centre, T.T.T.I. Post, Madras 600 113, India. Received April 29, 1994; accepted July 8, 1994. 0 1995 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
Seventeen cases of cystic meningiomas were found out of 232 meningiomas operated on between 1984 and 1993. Of these 17, six cysts were peritumoral and eleven were intratumoral. All six patients with peritumoral cysts (Table 1) were male and four out of the six were in the 41-50 age group. One patient was a 5-month-old infant. Four of the six patients had convexity meningiomas; of which three were parietal and one frontal in location. One patient had olfactory groove meningioma, whereas another had a torcular meningioma. Histopathologically, five were meningotheliomatous and one fibroblastic. All six cysts were type IV of Nauta’s classification of cystic meningiomas. Of the 17 meningiomas, 11 had intratumoral cysts (Table 2). These were Nauta type I in five patients and type II in six patients. One patient had cysts of 009~3019/95/$9.50 SSDI 009C-3019(94)00112-4
236
II
Surg Neurol 1995;43:235-9
Sridhar et al
Cystic Meningiomas-Peritumoral
Cysts 6/17 PATIENT
2
3
4
5
6
43 45 MMMMM +---i-t +--++ IV IV
41
33
43
-
-
+
+ IV
IV
_ IV
0.75 M + + _ IV
+ -
+ -
+ -
+ -
+
I Age (years) Sex Location: convexity Frontal Parietal Olfactory groove Torcular Nauta type Histologic Meningotheliomatous Fibroblastic
+ -
type I and type 11,whereas one patient had both an intratumoral and a peritumoral cyst. Out of the 11 cases, seven were female and four male. Four patients were in the 31-40 year age group, three in the 51-60 year, two in the 41-50 year, and one each in the 21-30 and above 60 year age groups. Eight out of the 11 cases were convexity meningiomas, of which five were parietal and three frontal in location. The other three were attached to the lateral sphenoidal wing. Histopathologically, there were three meningotheliomatous, five angioblastic, one mixed angioblastic and meningotheliomatous, one hemangiopericytic, and one anaplastic.
ILLUSTRATIVECASES CASE
4
A 33-year-old man was admitted with a history of one attack of a generalized seizure, which was followed by intense headache lasting 2 days. There
q Cystic
Meningiomas:
Intratumoral
CT scan of the brain showing a left parietal surfacing
0
mixed density lesion with a surrounding low attenuation-cystic meningioma Nauta type IV: case 4.
was no associated vomiting, visual difficulty, nor any post-ictal deficit. Clinical examination of the patient showed normal fundi and no neurologic deficit. Plain radiographs of the skull were normal. CT scan of the brain with and without contrast showed a left parietal irregularly enhancing surfacing lesion with a large cystic component deep in the lesion (Figure 1). There was no enhancement of the cyst wall. A provisional diagnosis of a left parietal cystic glioma was made. At surgery a soft friable tumor was found adherent to the convexity dura and completely extracerebral in location. The cyst lay deep
Cysts 1l/17 PATIENT
Age (years) Sex Location: convexity Frontal Parietal Sphenoidal wing Nauta type Histologic Meningotheliomatous Angioblastic Hemangiopericytoma Ananlastic
7
8
9
10
11
12
13
14
15
16
17
52 M + _ + _ II
40 M + _ + _ 1
40 F t + _ II
55 M _
46 F + + I & IV
54 F + + _ I
38 M + + _ _ I
35 F + _ _ I
40 F + + _ _ I
63 F _ _ _ II
29 F + _ + II
+ _ _ _
_ +
+ -
_ + _
+ _ -
+ + _ _
_ _ + _
_ + -
+ _ -
_ + _ _
&I + -
Surg Neurol 1995;43:235-9
Cystic Meningiomas
237
MRl scan of the brain: T,-weighted image showing a large cystic lesion with a surfacing mixed density nodule-cystic meningioma Nauta type IV: case 6.
in the tumor, between it and the underlying brain and contained xanthochromic fluid. Examination of the cyst wall showed only normal brain tissue. Histopathologically, the tumor was confirmed to be a meningioma. The patient made an uneventful recovery. CASE
6
A 9-month-old male child presented with a history of more than 3 months’ duration of episodes of altered sensorium associated with weakness of the right-sided limbs. There were no seizures. On examination the child was conscious and alert with normal fundi and cranial nerves, and with grade 2/5 right hemiparesis. Both the fontanelles were open. Other systems were normal. The head circumference was 56 cm. MRl scan of the brain (Figure 2) showed a large left-sided cyst with a mixed intensity nodule attached to the undersurface of the dura. There was compression of the ventricular system and gross midline shift. A parieta1 craniotomy was performed with the preoperative diagnosis of a cystic glioma with a mural nodule. The solid avascular lesion was found attached to the dura and partly to the grossly attenuated cortex. The large subdural cyst around the lesion contained clear CSF-like fluid. The lesion was removed totally. The child did well in the postoperative period. Histopathology of the lesion showed it to be a fibroblastic meningioma. CASE
8
A 40-year-old man presented with five episodes of generalized seizures with post-ictal deficit of weakness of the right lower limb. Examination revealed
CT scan of the brain contrast study showing a El hyperdense left parasagittal lesion with a central low attenuation-cystic
meningioma
Nauta type I: case 8.
bilateral papilledema and no other neurologic deficit. CT scan of the brain (Figure 3) done with and without contrast showed an isodense posterior parietal high convexity lesion with a central low density. On contrast, the isodense lesion became hyperdense-there being no change in the density of the central area. There was perilesional edema. At craniotomy the lesion had infiltrated the overlying bone and was attached to the high convexity dura and the lateral wall of the superior sagittal sinus. It was soft and vascular. The central portion of the tumor was cystic containing altered blood. The tumor was removed totally. Histologically the lesion was an anaplastic meningioma. Postoperatively the patient made an uneventful recovery. CASE 11 A 45-year-old woman was admitted with irrelevant speech of l-month duration and 3 days of urine incontinence. There was no history of trauma, seizures, or headache. Examination revealed an alert woman with irrelevant speech and frontal lobe signs. There was bilateral papilledema and no focal motor or sensory deficit. CT scan of the brain (Figure 4) done without contrast showed a large left frontal hyperdense lesion with multiple intralesional areas of low attenuation. There was also a large peritumoral low attenuation with pressure effect on the ventricular systems. A preoperative diagnosis of a left frontal glioma was made. At sur-
238
Surg Neurol 1995;43:235-9
0,
CT scan of the brain contrast study showing a left frontal surfacing lesion with areas of intratumoral low attenuation and a peritumoral cyst-cystic meningioma Nauta type II and IV.
gery, the lesion was attached to the dura, was wholly extracerebral, and was separated from the surrounding normal brain by cystic spaces containing xantho chromic fluid. The lesion itself had multiple small intratumoral cysts. Histologically, the lesion was confirmed to be an angioblastic meningioma.
DISCUSSION Cystic meningiomas are uncommon. In 1988, Fortuna et al [6], while reviewing 177 patients with cystic meningiomas in the literature, found that these formed only 1.7% of their series of meningiomas. Ramamurthi and Anguli [14] reported four cases in 1958 out of a total of 45 cases. Parisi et al [ 131 reported seven cases of cystic meningioma out of the 152 they had treated. The overall incidence of cysts found in association with meningiomas lies between 4% and 7% [3,13,16]. The authors found 17 cystic tumors among the 232 meningiomas operated between 1984 and 1993-incidence of 7.3%, which is a relatively higher figure than most series. Reports of cysts associated with meningiomas continue to be sporadic [ 1,6,12,13]. Although CT and MRl scans have made preoperative diagnosis easier, the confusion between cystic meningiomas and other intracranial cystic lesions has not been eliminated. Cystic meningiomas are more common in the pediatric age group than in adults. They are seen in
Sridhar et al
24% of all pediatric meningiomas and in 44% of meningiomas in the O-2 year age group [5]. The incidence of cyst formation in meningiomas in infants is remarkably higher than in childhood, adolescence, or adulthood [8,17]. The incidence of cysts is probably more common in males [ 71; we found 10 of the 17 cases to be males. The interesting feature is that all six meningiomas associated with peritumoral cysts were in males, whereas females predominated in tumors with intratumoral cysts. Cysts associated with meningiomas may be divided into intratumoral or peritumoral cysts depending on whether the cyst walls are lined by meningothelial cells [ 151. Intratumoral cysts are rare and arise mainly from degenerative and secre tory changes within the tumor. Fortuna et al [6] believe that intratumoral cysts develop because of microcystic degeneration, ischemic necrosis, and/ or hemorrhage. This may be in addition to secretory changes within the tumor [ 121. This is reflected in the finding of altered blood in some cysts, and xanthochromic fluid in others. Peritumoral cysts are large, contain xanthochromic fluid with a high protein content, and are lined by fibrillary astrocytes and their processes-a glial response to the presence of a meningioma. Rengachari et al [ 151 suggest that the finding of astrocytes with a degree of pleomorphism and hyperchromasia more than what is seen in reactive astrocytes could be related to the occasional finding of a fully developed glioma next to a meningioma. On CT, peritumoral cysts may be seen as a zone of diminished density of variable width surrounding the tumor. Pathologically, this zone of hypodensity could represent edema, widened subarachnoid space, loculated CSF, demyelination, an adjacent tumor, or a peritumoral cyst [2]. Peritumoral cysts are often larger than the main tumor mass and may account for the mass effect produced on the adjacent brain [9,15,20]. They contain acellular xanthochromic proteinaceous fluid [20]. We, however, found that occasionally the peritumoral cysts may contain clear CSF-like fluid as in case 6 of the series. These cysts are probably formed by a widening of the subarachnoid space or by loculation of the CSF by the tumor, or they may be true arachnoid cysts [ 121. Nauta et al [ 111 described four types of cysts associated with meningiomas: (1) a centrally located intratumoral cyst that is surrounded by macroscopic tumor throughout, (2) a peripherally situated intratumoral cyst, (3) a peritumoral cyst that actually lies within the adjacent brain, and (4) peritumoral cyst at the interface of tumor and brain. We found cysts of type 1 and II almost equally distributed between the intratumoral cysts. Of the peritu-
Cystic Meningiomas
moral cysts, all were Nauta type IV-cysts within the normal adjacent brain (Nauta type III) were not seen by us. From a surgical viewpoint the Nauta type II cysts are important, as neoplastic cells are found in the distal cyst wall [4]. It is therefore imperative that a careful search be made, and all neoplastic tissue be removed in such cases in order to prevent a recurrence. Szilwowski and Cummings [ 181 studied the chemical nature and enzyme levels of 214 cerebral cysts. The protein concentration from their two meningiomas was within the range for cysts associated with malignant tumors. Although the SCOT and LDH levels tended to be lower in meningioma cysts, these were not considered diagnostic. The high protein concentration found, similar to that in glial tumors, probably correlates with the higher incidence of malignant meningiomas seen in association with cysts [7]. In fact, Vassilouthis and Ambrose [19], when discussing the CT criteria for histologic aggressiveness of meningiomas, include cystic components as one of the factors. This correlation between cysts and malignant meningiomas was not apparent in our patients, with only one patient having an anaplastic meningioma. Whereas angioblastic and hemangiopericytic meningiomas are commonly associated with cysts [ 10,191, the angioblastic tumors in our series were all seen only with intratumoral cysts. The peritumoral cysts in the series were all associated with meningotheliomatous meningiomas except for the infant whose tumor was fibroblastic.
CONCLUSION Cysts associated with meningiomas, though uncommon, should be considered in the differential diagnosis of cystic surfacing lesions. Peritumoral and intratumoral cysts form separate subtypes with distinct characteristics. Meningiomas associated with peritumoral cysts appear to have a male predominance and are histologically benign. The cysts are more commonly Nauta type IV. They are large, and often they are the cause of the compression on the adjacent brain rather than the tumor itself. Meningiomas associated with intratumoral cysts, on the other hand, show a female predominance. These tumors are more likely to be angioblastic or hemangiopericytic on histology. The Nauta type II cysts require careful surgical removal to prevent recurrence. To say that cystic meningiomas are more likely to be malignant is probably not true. It is therefore important that a tissue diagnosis is procured for all surfacing lesions associated with cysts before deciding on the therapeutic
Surg Neurol 239 1995;43:235-9
regime, because what looks malignant on a CT or MRI scan may not always be so. REFERENCES 1. Aydin Y, Yolas C, Konte M, Aydin IH. Cystic meningi-
oma: report of two cases. Neurosurgery 1985;16:87-9. 2. Becker D, Norman D, Wilson CB. Computerized to-
mography and pathological correlation in cystic meningiomas: report of two cases. J Neurosurg 1979;50: 103-5. 3. Boixados JR, Labato RD, Estevez J, Cordoba A. Cystic meningiomas of the posterior fossa. Surg Neurol 1974; 2:289-91. 4. Bowen JH, Burger PC, Odom GL, Dubois PJ, Blue JM. Meningiomas associated with large cysts with neoplastic cells in the cyst walls: report of two cases. J Neurosurg 1981;55:473-8. 5. Ferante L, Acqui M, Artico M, Mastronardi L, Fortuna A. Paediatric intracranial meningiomas. Br J Neurosurg 1989;3: 189 -96. 6. Fortuna A, Ferante L, Acqui M, Guglielmi G, Mastronardi L. Cystic meningioma. Acta Neurochirur (Wien) 1988;90:23-30. 7. Guthrie BL, Ebersold MJ, Scheithauer BW. Neoplasms of intra-cranial meninges. In: Youmans JR, ed. Neurological surgery, Vol 5, Ed. III. Philadelphia: WB Saunders, 1990:32-53. 8. Herz DA, Shapiro K, Shulman K. Intracranial meningiomas of infancy, childhood, and adolescence: a review of literature and addition of nine case reports. Childs Brain 1980;7:43-56. 9. Katayama Y, Tsubokawa T, Yoshida K. Cystic meningiomas in infancy. Surg Neurol 1986;25:43-8. 10. Lake P, Heiden JS, Minckler J. Cystic meningiomas: case report. J Neurosurg 1975;38:638-41. 11. Nauta HJW, Tucker WS, Horsey WJ, Bilbao JM, Gonsalves C. Xanthochromic cysts associated with meningiomas. J Neurol Neurosurg Psychiatry 1979; 42: 529-35. 12. Odake G. Cystic meningioma: report of three patients. Neurosurgery 1992;30:935-40. 13. Parisi G, Tropea R, Giuffrida S, Lombard0 M, Giuffre F. Cystic meningioma: a report of seven cases. J Neurosurg 1986;54:35-8. 14. Ramamurthi B, Anguli VC. Meningiomas with cystic changes. Neurol India 1958;6:42-6. 15. Rengachari S, Batnitzky S, Kepes JJ, Morantz RA, O’Boynick P, Watanabe I. Cystic lesions associated with intracranial meningiomas. Neurosurgery 1979;4:107-10. 16. Russel EJ, George AE, Kriceff II, Budzilovich G. Atypical computed tomographic features of intracranial meningiomas. Radiological-pathological correlation in a series of 131 consecutive cases. Radiology 1980; 135:673-82. 17. Sano K, Wakai S, Ochiai C, Takakura K. Characteristics of intracranial meningiomas in childhood. Childs Brain 1981;8:98-106. 18. Szilwowski HB, Cummings JN. Diagnostic value of chemical examination of cerebral cyst fluids. Brain 1961;84:202-12. 19. Vassilouthis J, Ambrose J. Computerized tomography scanning appearances of intracranial meningiomas. J Neurosurg 1979;50:320-7. 20. Worthington C, Caron JL, Melanson D, LeBlanc R. Meningioma cysts. Neurology 1985;35:1720-4.
Featured Subject: Management of Brain Tumors
CYSTIC MENINGIOMAS K. Sridhar, D.N.B. (Neurosurgery), and M.C. Vasudevan, M.D.
R. Ravi, M.S., B. Ramamurthi,
M.S.,
A. Lakshmipathi Neurosurgical Centre, Voluntary Health Services Medical Centre, Madras, India
Sridhar giomas.
K, Ravi R, Ramamurthi B, Vasudevan Surg Neural 1995;43:235-9.
MC. Cystic
menin-
BACKGROUND
Meningiomas are generally solid tumors and are easily diagnosed by CT scans and MRf scans. Rarely are these tumors associated with cysts that can cause a confusion in the pre- and intraoperative diagnosis. Cysts associated with meningiomas may be intratumoral or peritumoral. METHODS
with meningiomas
is between
4% and 7% [3,12,15].
Even though it is easier to recognize cysts with modern imaging techniques, the differentiation of cystic meningiomas from other cystic tumors of the brain is difficult. The authors present their experience with 17 cases of cystic meningiomas.
MATERIALSANDMETHODS
The authors conducted a retrospective study of the seventeen meningiomas, out of a total number of 232, which were associated with cysts. The cysts were classified based on their relationship to the tumor. The patients’ sex, age group, location of the tumor, and pathological type of tumor were also analyzed. RESULTS The 17 cases of cystic meningioma formed 7.3% of the meningiomas seen between 1984 and 1993. Eleven of these were intratumoral and 6 peritumoral. One case had both intra- and peritumoral cysts. The tumors were found mostly in the fourth and fifth decades of life. Histologically, all the peritumoral cysts except one were associated with meningotheliomatous meningiomas. Tumors with peritumoral cysts were more common in males. lntratumoral cysts, more common in females, were angioblastic or meningotheliomatous on histopathology. Only one case was an anaplastic meningioma.
A retrospective study was undertaken of 232 cases of intracranial meningioma operated between 1984 and 1993 at the Dr. Achanta Lakshmipathi Neurosurgical Centre, Madras. Of these meningiomas, 17 were found to be associated with cysts. The relationship of the cysts to the tumors was analyzed. The cysts were classified into intratumoral and peritumoral cysts based on their relationship to the tumor, and also according to the types as described by Nauta et al [ 121. The patients’ sex, age group, the location of the tumor, and the pathologic type of tumor were also analyzed.
CONCLUSION
RESULTS
Cysts associated with meningiomas, although uncommon, are certainly not rare. The peritumoral and the intratumoral cysts form distinct subtypes needing separate consideration. Cystic meningiomas are only rarely malignant. KEY WORDS
Cyst, intratumoral, meningioma,
peritumoral.
M
eningiomas are generally known to be solid tumors and their classical appearance on the computed tomography (CT) scan and magnetic resonance imaging (MRI) usually leads to a correct diagnosis. Cysts associated with meningiomas are uncommon. The incidence of cysts in association Address reprint requests to: K. Sridhar, M.D., A. Lakshmipathi Neurosurgical Centre, Voluntary Health Services Medical Centre, T.T.T.I. Post, Madras 600 113, India. Received April 29, 1994; accepted July 8, 1994. 0 1995 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
Seventeen cases of cystic meningiomas were found out of 232 meningiomas operated on between 1984 and 1993. Of these 17, six cysts were peritumoral and eleven were intratumoral. All six patients with peritumoral cysts (Table 1) were male and four out of the six were in the 41-50 age group. One patient was a 5-month-old infant. Four of the six patients had convexity meningiomas; of which three were parietal and one frontal in location. One patient had olfactory groove meningioma, whereas another had a torcular meningioma. Histopathologically, five were meningotheliomatous and one fibroblastic. All six cysts were type IV of Nauta’s classification of cystic meningiomas. Of the 17 meningiomas, 11 had intratumoral cysts (Table 2). These were Nauta type I in five patients and type II in six patients. One patient had cysts of 009~3019/95/$9.50 SSDI 009C-3019(94)00112-4
236
II
Surg Neurol 1995;43:235-9
Sridhar et al
Cystic Meningiomas-Peritumoral
Cysts 6/17 PATIENT
2
3
4
5
6
43 45 MMMMM +---i-t +--++ IV IV
41
33
43
-
-
+
+ IV
IV
_ IV
0.75 M + + _ IV
+ -
+ -
+ -
+ -
+
I Age (years) Sex Location: convexity Frontal Parietal Olfactory groove Torcular Nauta type Histologic Meningotheliomatous Fibroblastic
+ -
type I and type 11,whereas one patient had both an intratumoral and a peritumoral cyst. Out of the 11 cases, seven were female and four male. Four patients were in the 31-40 year age group, three in the 51-60 year, two in the 41-50 year, and one each in the 21-30 and above 60 year age groups. Eight out of the 11 cases were convexity meningiomas, of which five were parietal and three frontal in location. The other three were attached to the lateral sphenoidal wing. Histopathologically, there were three meningotheliomatous, five angioblastic, one mixed angioblastic and meningotheliomatous, one hemangiopericytic, and one anaplastic.
ILLUSTRATIVECASES CASE
4
A 33-year-old man was admitted with a history of one attack of a generalized seizure, which was followed by intense headache lasting 2 days. There
q Cystic
Meningiomas:
Intratumoral
CT scan of the brain showing a left parietal surfacing
0
mixed density lesion with a surrounding low attenuation-cystic meningioma Nauta type IV: case 4.
was no associated vomiting, visual difficulty, nor any post-ictal deficit. Clinical examination of the patient showed normal fundi and no neurologic deficit. Plain radiographs of the skull were normal. CT scan of the brain with and without contrast showed a left parietal irregularly enhancing surfacing lesion with a large cystic component deep in the lesion (Figure 1). There was no enhancement of the cyst wall. A provisional diagnosis of a left parietal cystic glioma was made. At surgery a soft friable tumor was found adherent to the convexity dura and completely extracerebral in location. The cyst lay deep
Cysts 1l/17 PATIENT
Age (years) Sex Location: convexity Frontal Parietal Sphenoidal wing Nauta type Histologic Meningotheliomatous Angioblastic Hemangiopericytoma Ananlastic
7
8
9
10
11
12
13
14
15
16
17
52 M + _ + _ II
40 M + _ + _ 1
40 F t + _ II
55 M _
46 F + + I & IV
54 F + + _ I
38 M + + _ _ I
35 F + _ _ I
40 F + + _ _ I
63 F _ _ _ II
29 F + _ + II
+ _ _ _
_ +
+ -
_ + _
+ _ -
+ + _ _
_ _ + _
_ + -
+ _ -
_ + _ _
&I + -
Surg Neurol 1995;43:235-9
Cystic Meningiomas
237
MRl scan of the brain: T,-weighted image showing a large cystic lesion with a surfacing mixed density nodule-cystic meningioma Nauta type IV: case 6.
in the tumor, between it and the underlying brain and contained xanthochromic fluid. Examination of the cyst wall showed only normal brain tissue. Histopathologically, the tumor was confirmed to be a meningioma. The patient made an uneventful recovery. CASE
6
A 9-month-old male child presented with a history of more than 3 months’ duration of episodes of altered sensorium associated with weakness of the right-sided limbs. There were no seizures. On examination the child was conscious and alert with normal fundi and cranial nerves, and with grade 2/5 right hemiparesis. Both the fontanelles were open. Other systems were normal. The head circumference was 56 cm. MRl scan of the brain (Figure 2) showed a large left-sided cyst with a mixed intensity nodule attached to the undersurface of the dura. There was compression of the ventricular system and gross midline shift. A parieta1 craniotomy was performed with the preoperative diagnosis of a cystic glioma with a mural nodule. The solid avascular lesion was found attached to the dura and partly to the grossly attenuated cortex. The large subdural cyst around the lesion contained clear CSF-like fluid. The lesion was removed totally. The child did well in the postoperative period. Histopathology of the lesion showed it to be a fibroblastic meningioma. CASE
8
A 40-year-old man presented with five episodes of generalized seizures with post-ictal deficit of weakness of the right lower limb. Examination revealed
CT scan of the brain contrast study showing a El hyperdense left parasagittal lesion with a central low attenuation-cystic
meningioma
Nauta type I: case 8.
bilateral papilledema and no other neurologic deficit. CT scan of the brain (Figure 3) done with and without contrast showed an isodense posterior parietal high convexity lesion with a central low density. On contrast, the isodense lesion became hyperdense-there being no change in the density of the central area. There was perilesional edema. At craniotomy the lesion had infiltrated the overlying bone and was attached to the high convexity dura and the lateral wall of the superior sagittal sinus. It was soft and vascular. The central portion of the tumor was cystic containing altered blood. The tumor was removed totally. Histologically the lesion was an anaplastic meningioma. Postoperatively the patient made an uneventful recovery. CASE 11 A 45-year-old woman was admitted with irrelevant speech of l-month duration and 3 days of urine incontinence. There was no history of trauma, seizures, or headache. Examination revealed an alert woman with irrelevant speech and frontal lobe signs. There was bilateral papilledema and no focal motor or sensory deficit. CT scan of the brain (Figure 4) done without contrast showed a large left frontal hyperdense lesion with multiple intralesional areas of low attenuation. There was also a large peritumoral low attenuation with pressure effect on the ventricular systems. A preoperative diagnosis of a left frontal glioma was made. At sur-
238
Surg Neurol 1995;43:235-9
0,
CT scan of the brain contrast study showing a left frontal surfacing lesion with areas of intratumoral low attenuation and a peritumoral cyst-cystic meningioma Nauta type II and IV.
gery, the lesion was attached to the dura, was wholly extracerebral, and was separated from the surrounding normal brain by cystic spaces containing xantho chromic fluid. The lesion itself had multiple small intratumoral cysts. Histologically, the lesion was confirmed to be an angioblastic meningioma.
DISCUSSION Cystic meningiomas are uncommon. In 1988, Fortuna et al [6], while reviewing 177 patients with cystic meningiomas in the literature, found that these formed only 1.7% of their series of meningiomas. Ramamurthi and Anguli [14] reported four cases in 1958 out of a total of 45 cases. Parisi et al [ 131 reported seven cases of cystic meningioma out of the 152 they had treated. The overall incidence of cysts found in association with meningiomas lies between 4% and 7% [3,13,16]. The authors found 17 cystic tumors among the 232 meningiomas operated between 1984 and 1993-incidence of 7.3%, which is a relatively higher figure than most series. Reports of cysts associated with meningiomas continue to be sporadic [ 1,6,12,13]. Although CT and MRl scans have made preoperative diagnosis easier, the confusion between cystic meningiomas and other intracranial cystic lesions has not been eliminated. Cystic meningiomas are more common in the pediatric age group than in adults. They are seen in
Sridhar et al
24% of all pediatric meningiomas and in 44% of meningiomas in the O-2 year age group [5]. The incidence of cyst formation in meningiomas in infants is remarkably higher than in childhood, adolescence, or adulthood [8,17]. The incidence of cysts is probably more common in males [ 71; we found 10 of the 17 cases to be males. The interesting feature is that all six meningiomas associated with peritumoral cysts were in males, whereas females predominated in tumors with intratumoral cysts. Cysts associated with meningiomas may be divided into intratumoral or peritumoral cysts depending on whether the cyst walls are lined by meningothelial cells [ 151. Intratumoral cysts are rare and arise mainly from degenerative and secre tory changes within the tumor. Fortuna et al [6] believe that intratumoral cysts develop because of microcystic degeneration, ischemic necrosis, and/ or hemorrhage. This may be in addition to secretory changes within the tumor [ 121. This is reflected in the finding of altered blood in some cysts, and xanthochromic fluid in others. Peritumoral cysts are large, contain xanthochromic fluid with a high protein content, and are lined by fibrillary astrocytes and their processes-a glial response to the presence of a meningioma. Rengachari et al [ 151 suggest that the finding of astrocytes with a degree of pleomorphism and hyperchromasia more than what is seen in reactive astrocytes could be related to the occasional finding of a fully developed glioma next to a meningioma. On CT, peritumoral cysts may be seen as a zone of diminished density of variable width surrounding the tumor. Pathologically, this zone of hypodensity could represent edema, widened subarachnoid space, loculated CSF, demyelination, an adjacent tumor, or a peritumoral cyst [2]. Peritumoral cysts are often larger than the main tumor mass and may account for the mass effect produced on the adjacent brain [9,15,20]. They contain acellular xanthochromic proteinaceous fluid [20]. We, however, found that occasionally the peritumoral cysts may contain clear CSF-like fluid as in case 6 of the series. These cysts are probably formed by a widening of the subarachnoid space or by loculation of the CSF by the tumor, or they may be true arachnoid cysts [ 121. Nauta et al [ 111 described four types of cysts associated with meningiomas: (1) a centrally located intratumoral cyst that is surrounded by macroscopic tumor throughout, (2) a peripherally situated intratumoral cyst, (3) a peritumoral cyst that actually lies within the adjacent brain, and (4) peritumoral cyst at the interface of tumor and brain. We found cysts of type 1 and II almost equally distributed between the intratumoral cysts. Of the peritu-
Cystic Meningiomas
moral cysts, all were Nauta type IV-cysts within the normal adjacent brain (Nauta type III) were not seen by us. From a surgical viewpoint the Nauta type II cysts are important, as neoplastic cells are found in the distal cyst wall [4]. It is therefore imperative that a careful search be made, and all neoplastic tissue be removed in such cases in order to prevent a recurrence. Szilwowski and Cummings [ 181 studied the chemical nature and enzyme levels of 214 cerebral cysts. The protein concentration from their two meningiomas was within the range for cysts associated with malignant tumors. Although the SCOT and LDH levels tended to be lower in meningioma cysts, these were not considered diagnostic. The high protein concentration found, similar to that in glial tumors, probably correlates with the higher incidence of malignant meningiomas seen in association with cysts [7]. In fact, Vassilouthis and Ambrose [19], when discussing the CT criteria for histologic aggressiveness of meningiomas, include cystic components as one of the factors. This correlation between cysts and malignant meningiomas was not apparent in our patients, with only one patient having an anaplastic meningioma. Whereas angioblastic and hemangiopericytic meningiomas are commonly associated with cysts [ 10,191, the angioblastic tumors in our series were all seen only with intratumoral cysts. The peritumoral cysts in the series were all associated with meningotheliomatous meningiomas except for the infant whose tumor was fibroblastic.
CONCLUSION Cysts associated with meningiomas, though uncommon, should be considered in the differential diagnosis of cystic surfacing lesions. Peritumoral and intratumoral cysts form separate subtypes with distinct characteristics. Meningiomas associated with peritumoral cysts appear to have a male predominance and are histologically benign. The cysts are more commonly Nauta type IV. They are large, and often they are the cause of the compression on the adjacent brain rather than the tumor itself. Meningiomas associated with intratumoral cysts, on the other hand, show a female predominance. These tumors are more likely to be angioblastic or hemangiopericytic on histology. The Nauta type II cysts require careful surgical removal to prevent recurrence. To say that cystic meningiomas are more likely to be malignant is probably not true. It is therefore important that a tissue diagnosis is procured for all surfacing lesions associated with cysts before deciding on the therapeutic
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