1992, The British Journal of Radiology, 65, 754^757
..5
Primary choroid plexus papilloma of the cerebellopontine angle: magnetic resonance imaging, computed tomographic and angiographic appearances By A. Jackson, PhD, MRCP, FRCR, *B. J. Panizza, MB, BS, MBA, D. Hughes, FRCR and tH. Reid, FRCPath Departments of Neuroradiology, *Otolaryngology and tNeuropathology, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK (Received 20 November 1991, accepted 6 May 1992) Keywords: CT, MRI, Cerebellopontine angle, Choroid plexus papilloma Abstract. The computed tomographic, angiographic and magnetic resonance imaging (MRI) appearances of a benign primary choroid plexus papilloma of the cerebellopontine angle are reported. Although benign, this tumour showed local invasion of the petrous temporal bone and mastoid air cells. The differential diagnosis of cerebellopontine angle lesions is discussed. Papilloma is suggested by the presence of a vascular, calcined, enhancing extra-axial mass in or around the cerebellopontine angle. MRI may show evidence of high vascularity and internal haemorrhage. Differentiation from other cerebellopontine tumours, most particularly meningioma, may not be possible on radiological features.
Choroid plexus papillomas are benign neoplasms of the neuroectoderm, which are commonest in children where they account for 3% of intracranial tumours. In adults, papilloma accounts for only 0.5% of intracranial tumours and the great majority occur within the ventricular system, predominantly in the lateral and 4th ventricles (Rovit et al, 1970). Primary choroid plexus papilloma of the cerebellopontine angle has been described in only 20 previous cases and the magnetic resonance imaging (MRI) appearances in only one (Martin et al, 1990). The case presented here has a number of distinctive radiological features which are of interest in the differential diagnosis of tumours in the cerebellopontine region. Case report
A 24-year-old woman presented with a 1-year history of deafness and tinnitus in the left ear. A few months prior to presentation she developed intermittent leftsided hemifacial spasm, which resolved spontaneously. Initial investigations demonstrated a conductive hearing loss but no focal neurological signs were elicited. A computed tomographic (CT) scan (Fig. 1) demonstrated an isodense enhancing mass in the cerebellopontine angle (CPA) with evidence of invasion along the posterior aspect of-the petrous bone and into the medial aspect of the mastoid air cells. There was no evidence of tumoral calcification. The adjacent cerebellum showed minor shift but there was no evidence of oedema and no features of parenchymal invasion. An MRI scan performed on a 0.5 T scanner demonstrated a markedly heterogeneous tumour mass on Tx -weighted sequences (Fig. 2a) with areas of focal high intensity around the periphery of the tumour and a heterogeneous internal signal intensity with focal areas of both high and low signal. T^-weighted sequences showed a high-signal754
intensity lesion, again with areas of heterogeneous internal signal (Fig. 2b). Following intravenous gadolinium DTPA (Fig. 2c) the mass showed significant but incomplete enhancement affecting mainly the medial part of the tumour. There was no evidence on any sequence of cerebellar or brainstem invasion or oedema. Angiography (Fig. 3) showed a moderately vascular tumour fed entirely by branches of the external carotid artery arising principally from the occipital branch. At surgery, the tumour was found to lie predominantly extradurally and to be invading the petrous bone. There was a small en plaque element involving the dura. The tumour was removed via a combined suboccipital and translabyrinthine approach. Histological examination demonstrated fronds offibrovasculartissue covered by uniform cuboidal epithelial cells; immunoperoxidase stains were positive for epithelial membrane antigen SI00 and some cells were positive for glial fibrillary acidic protein and carbonic anhydrase. The diagnosis of extradural benign choroid plexus papilloma was made. Discussion
Choroid plexus papillomas within the CPA usually develop either as a direct extension of 4th ventricular tumours or due to seeding along cerebrospinal fluid (CSF) pathways from an intraventricular papilloma (Rovit et al, 1970; Russell & Rubenstein, 1971). Only 20 cases of primary extraventricular papillomas have previously been reported (Devadiga et al, 1969; Picard et al, 1979; Martin et al, 1990). In the majority of these cases the tumour was shown to originate from the small choroid tuft which normally protrudes from the foramen of Lushka; however, in several cases, including the one reported here, there has been no evidence of a tumour hilum and a primarily extrudural location has The British Journal of Radiology, September 1992
Primary choroid plexus papilloma of the cerebellopontine angle
(a) (b) Figure 1. (a) Pre-contrast scan demonstrates erosion of the left petrous temporal bone and tumour invasion into the mastoid air cells, (b) Post-contrast scan demonstrates a well-defined enhancing mass in the cerebellopontine angle.
been identified (Naguib et al, 1981). The angiographic demonstration of an external carotid supply to the tumour is also in contrast to choroid plexus papillomas of the ventricular system, including those which spread to the CPA, all of which have a predominantly internal carotid or vertebral artery supply (Rovit et al, 1970). Thesefindingssupport the suggestion that CPA papillomas may develop from an extradural embryonic remnant of choroid tissue (Martin et al, 1990). CPA papillomas are very slow growing and most commonly present between the 1st and 4th decades. Symptoms are usually slow in onset and include ataxia, V, VII and VIII nerve palsies and sometimes dysphagia. It is interesting to note that the development of hemifacial spasm as seen in the present case has been reported previously following development of a choroid plexus papilloma in the foramen magnum (Domingues et al, 1991). Clinical presentation may occasionally be acute with the development of secondary hydrocephalus due to brainstem compression or secondary extension into the 4th ventricle. Previous reports have described a non-specific CT appearance of a well-delineated mass with marked enhancement after intravenous contrast medium. In contrast to the current case, intratumoral calcification has been described in the majority of previous reports (Picard et al, 1979; Naguib et al, 1981; Ford et al, 1988; Martin et al, 1990). The finding of tumoral invasion of the adjacent petrous bone is unusual and has been described in only two previous cases. Naguib et al (1981) described a primary papilloma of the CPA invading the petrous bone and mastoid air cells similar to this case. Martin et al (1990) described a similar tumour with invasion of the cavernous sinus. It is important to realize that this invasive tendency, Vol. 65, No. 777
commonly associated with choroid plexus carcinoma, is not necessarily an indicator of malignancy and could provide a useful diagnostic clue. The MRI appearances of primary choroid plexus papilloma of the CPA have been described in only one previous case and were similar to those presented here (Martin et al, 1990). The presence of areas of signal void on r,-weighted images seen in both cases presumably corresponds to the rich vascular supply and has been previously described in intraventricular choroid plexus papilloma. The areas of marked hyperintensity at the margin of the tumour on short-TR images were histologically demonstrated to correspond to foci of haemorrhagic necrosis. A single similar focus was seen in the case of Martin et al (1990). The post-gadolinium appearances of these tumours have not been previously described and the presence of marked enhancement is entirely in keeping with the vascular nature of the tumour. The heterogeneity of enhancement presumably reflects regional tumour necrosis. The differential diagnosis of tumours within the CPA can be difficult when based entirely on radiological features. CPA tumours consist predominantly of acoustic neuromas (75-90% of CPA masses) and meningiomas (2-10%, Russell & Rubenstein, 1971). A large acoustic neuroma may show areas of calcification and significant heterogeneity on MR images; however, evidence of tumoral vascularity and the lack of involvement of the internal auditory meatus made this unlikely in the current case. Differentiation from meningioma on the other hand may be impossible and this was indeed the favoured radiological diagnosis in the present case (Zimmerman etal, 1985; Martin etal, 1990). Tumours metastatic to the CPA may have a similar appearance to that described here and have been mistaken previously 755
A. Jackson, B. J. Panizza, D. Hughes and H. Refti
(c)
Figure 2. (a) Coronal T{ spin-echo image demonstrates a mass in the left CPA with areas of internal signal void and peripheral areas of high signal, (b) Axial T2 spin-echo image demonstrating heterogeneous high signal intensity, (c) Coronal Tx -weighted image following intravenous gadolinium demonstrates marked but heterogeneous contrast enhancement.
for acoustic neuroma and meningioma. Finally, radiological differentiation from other primary CPA masses such as arachnoid cysts, paragangliomas, epidermoid cysts and lipomas does not pose a problem since these have widely differing appearances on both CT and MRI. In summary, primary benign choroid plexus papilloma of the CPA is an uncommon lesion which closely resembles meningioma. The presence of features 756
Figure 3. External carotid angiogram shows a vascular tumour fed principally by a branch of the occipital artery. The British Journal of Radiology, September 1992
Primary choroid plexus papilloma of the cerebellopontine angle
indicating local invasion, internal ischaemia or haemorrhagic necrosis may provide pre-operative diagnostic indicators. References DEVADIGA, K. V., ABRAHAM, J. & CHANDY, J., 1969. Primary
choroid plexus papilloma of the cerebellopontine angle. Case report. Journal of Neurosurgery, 30', 286-288. DOMINGUES, R. C , TAVERAS, J. M., REIMER, P. & ROSEN, B. R.,
1991. Foramen magnum choroid plexus papilloma with drop metastases to the lumbar spine. American Journal of Neuroradiology, 12, 564-565. FORD, W. J., BROOKS, B. S., GAMMAL, T. & MASSEY, C. E.,
1988. Adult cerebellopontine MR evaluation. papilloma: Neuroradiology, 9, 611.
angle choroid plexus American Journal of
MARTIN, N., PIEROT, L., STERKERS, O., MOMPOINT, D. &
NAHUM, H., 1990. Primary choroid plexus papilloma of the
VoL 65, No. 777
cerebellopontine angle: MR imaging. Neuroradiology, 31, 541-543. NAGUIB, M. G., CHOU, S. N. & MASTRI, A., 1981. Radiation
therapy of a choroid plexus papilloma of the cerebellopontine angle with bone involvement. Journal of Neurosurgery, 54, 245-247. PlCARD,
C,
COPTY,
M.,
LAVOIE,
G.,
MlCHAUD,
J.
&
BOUCHARD, R., 1979. A primary choroid plexus papilloma of the cerebellopontine angle. Surgical Neurology, 12, 123-127. ROVIT,
R. L.,
SCHECTER,
M. M.
& CHODROFF, P.,
1970.
Choroid plexus papillomas: observations on radiographic diagnosis. American Journal of Roentgenology, 110, 608-617. RUSSELL,
D. S. & RUBENSTEIN,
L. J.,
1971. Pathology
of
Tumours of the Nervous System (Edward Arnold, London), p. 163. ZIMMERMAN, R. D., FLEMING, C. A., SAINT LOUIS, L. A., LEE, B. C. P., MANNING, J. J. & DECK, M. D. F., 1985. Magnetic
resonance imaging of meningiomas. American Journal of Neuroradiology, 6, 149-157.
757
..5
Primary choroid plexus papilloma of the cerebellopontine angle: magnetic resonance imaging, computed tomographic and angiographic appearances By A. Jackson, PhD, MRCP, FRCR, *B. J. Panizza, MB, BS, MBA, D. Hughes, FRCR and tH. Reid, FRCPath Departments of Neuroradiology, *Otolaryngology and tNeuropathology, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK (Received 20 November 1991, accepted 6 May 1992) Keywords: CT, MRI, Cerebellopontine angle, Choroid plexus papilloma Abstract. The computed tomographic, angiographic and magnetic resonance imaging (MRI) appearances of a benign primary choroid plexus papilloma of the cerebellopontine angle are reported. Although benign, this tumour showed local invasion of the petrous temporal bone and mastoid air cells. The differential diagnosis of cerebellopontine angle lesions is discussed. Papilloma is suggested by the presence of a vascular, calcined, enhancing extra-axial mass in or around the cerebellopontine angle. MRI may show evidence of high vascularity and internal haemorrhage. Differentiation from other cerebellopontine tumours, most particularly meningioma, may not be possible on radiological features.
Choroid plexus papillomas are benign neoplasms of the neuroectoderm, which are commonest in children where they account for 3% of intracranial tumours. In adults, papilloma accounts for only 0.5% of intracranial tumours and the great majority occur within the ventricular system, predominantly in the lateral and 4th ventricles (Rovit et al, 1970). Primary choroid plexus papilloma of the cerebellopontine angle has been described in only 20 previous cases and the magnetic resonance imaging (MRI) appearances in only one (Martin et al, 1990). The case presented here has a number of distinctive radiological features which are of interest in the differential diagnosis of tumours in the cerebellopontine region. Case report
A 24-year-old woman presented with a 1-year history of deafness and tinnitus in the left ear. A few months prior to presentation she developed intermittent leftsided hemifacial spasm, which resolved spontaneously. Initial investigations demonstrated a conductive hearing loss but no focal neurological signs were elicited. A computed tomographic (CT) scan (Fig. 1) demonstrated an isodense enhancing mass in the cerebellopontine angle (CPA) with evidence of invasion along the posterior aspect of-the petrous bone and into the medial aspect of the mastoid air cells. There was no evidence of tumoral calcification. The adjacent cerebellum showed minor shift but there was no evidence of oedema and no features of parenchymal invasion. An MRI scan performed on a 0.5 T scanner demonstrated a markedly heterogeneous tumour mass on Tx -weighted sequences (Fig. 2a) with areas of focal high intensity around the periphery of the tumour and a heterogeneous internal signal intensity with focal areas of both high and low signal. T^-weighted sequences showed a high-signal754
intensity lesion, again with areas of heterogeneous internal signal (Fig. 2b). Following intravenous gadolinium DTPA (Fig. 2c) the mass showed significant but incomplete enhancement affecting mainly the medial part of the tumour. There was no evidence on any sequence of cerebellar or brainstem invasion or oedema. Angiography (Fig. 3) showed a moderately vascular tumour fed entirely by branches of the external carotid artery arising principally from the occipital branch. At surgery, the tumour was found to lie predominantly extradurally and to be invading the petrous bone. There was a small en plaque element involving the dura. The tumour was removed via a combined suboccipital and translabyrinthine approach. Histological examination demonstrated fronds offibrovasculartissue covered by uniform cuboidal epithelial cells; immunoperoxidase stains were positive for epithelial membrane antigen SI00 and some cells were positive for glial fibrillary acidic protein and carbonic anhydrase. The diagnosis of extradural benign choroid plexus papilloma was made. Discussion
Choroid plexus papillomas within the CPA usually develop either as a direct extension of 4th ventricular tumours or due to seeding along cerebrospinal fluid (CSF) pathways from an intraventricular papilloma (Rovit et al, 1970; Russell & Rubenstein, 1971). Only 20 cases of primary extraventricular papillomas have previously been reported (Devadiga et al, 1969; Picard et al, 1979; Martin et al, 1990). In the majority of these cases the tumour was shown to originate from the small choroid tuft which normally protrudes from the foramen of Lushka; however, in several cases, including the one reported here, there has been no evidence of a tumour hilum and a primarily extrudural location has The British Journal of Radiology, September 1992
Primary choroid plexus papilloma of the cerebellopontine angle
(a) (b) Figure 1. (a) Pre-contrast scan demonstrates erosion of the left petrous temporal bone and tumour invasion into the mastoid air cells, (b) Post-contrast scan demonstrates a well-defined enhancing mass in the cerebellopontine angle.
been identified (Naguib et al, 1981). The angiographic demonstration of an external carotid supply to the tumour is also in contrast to choroid plexus papillomas of the ventricular system, including those which spread to the CPA, all of which have a predominantly internal carotid or vertebral artery supply (Rovit et al, 1970). Thesefindingssupport the suggestion that CPA papillomas may develop from an extradural embryonic remnant of choroid tissue (Martin et al, 1990). CPA papillomas are very slow growing and most commonly present between the 1st and 4th decades. Symptoms are usually slow in onset and include ataxia, V, VII and VIII nerve palsies and sometimes dysphagia. It is interesting to note that the development of hemifacial spasm as seen in the present case has been reported previously following development of a choroid plexus papilloma in the foramen magnum (Domingues et al, 1991). Clinical presentation may occasionally be acute with the development of secondary hydrocephalus due to brainstem compression or secondary extension into the 4th ventricle. Previous reports have described a non-specific CT appearance of a well-delineated mass with marked enhancement after intravenous contrast medium. In contrast to the current case, intratumoral calcification has been described in the majority of previous reports (Picard et al, 1979; Naguib et al, 1981; Ford et al, 1988; Martin et al, 1990). The finding of tumoral invasion of the adjacent petrous bone is unusual and has been described in only two previous cases. Naguib et al (1981) described a primary papilloma of the CPA invading the petrous bone and mastoid air cells similar to this case. Martin et al (1990) described a similar tumour with invasion of the cavernous sinus. It is important to realize that this invasive tendency, Vol. 65, No. 777
commonly associated with choroid plexus carcinoma, is not necessarily an indicator of malignancy and could provide a useful diagnostic clue. The MRI appearances of primary choroid plexus papilloma of the CPA have been described in only one previous case and were similar to those presented here (Martin et al, 1990). The presence of areas of signal void on r,-weighted images seen in both cases presumably corresponds to the rich vascular supply and has been previously described in intraventricular choroid plexus papilloma. The areas of marked hyperintensity at the margin of the tumour on short-TR images were histologically demonstrated to correspond to foci of haemorrhagic necrosis. A single similar focus was seen in the case of Martin et al (1990). The post-gadolinium appearances of these tumours have not been previously described and the presence of marked enhancement is entirely in keeping with the vascular nature of the tumour. The heterogeneity of enhancement presumably reflects regional tumour necrosis. The differential diagnosis of tumours within the CPA can be difficult when based entirely on radiological features. CPA tumours consist predominantly of acoustic neuromas (75-90% of CPA masses) and meningiomas (2-10%, Russell & Rubenstein, 1971). A large acoustic neuroma may show areas of calcification and significant heterogeneity on MR images; however, evidence of tumoral vascularity and the lack of involvement of the internal auditory meatus made this unlikely in the current case. Differentiation from meningioma on the other hand may be impossible and this was indeed the favoured radiological diagnosis in the present case (Zimmerman etal, 1985; Martin etal, 1990). Tumours metastatic to the CPA may have a similar appearance to that described here and have been mistaken previously 755
A. Jackson, B. J. Panizza, D. Hughes and H. Refti
(c)
Figure 2. (a) Coronal T{ spin-echo image demonstrates a mass in the left CPA with areas of internal signal void and peripheral areas of high signal, (b) Axial T2 spin-echo image demonstrating heterogeneous high signal intensity, (c) Coronal Tx -weighted image following intravenous gadolinium demonstrates marked but heterogeneous contrast enhancement.
for acoustic neuroma and meningioma. Finally, radiological differentiation from other primary CPA masses such as arachnoid cysts, paragangliomas, epidermoid cysts and lipomas does not pose a problem since these have widely differing appearances on both CT and MRI. In summary, primary benign choroid plexus papilloma of the CPA is an uncommon lesion which closely resembles meningioma. The presence of features 756
Figure 3. External carotid angiogram shows a vascular tumour fed principally by a branch of the occipital artery. The British Journal of Radiology, September 1992
Primary choroid plexus papilloma of the cerebellopontine angle
indicating local invasion, internal ischaemia or haemorrhagic necrosis may provide pre-operative diagnostic indicators. References DEVADIGA, K. V., ABRAHAM, J. & CHANDY, J., 1969. Primary
choroid plexus papilloma of the cerebellopontine angle. Case report. Journal of Neurosurgery, 30', 286-288. DOMINGUES, R. C , TAVERAS, J. M., REIMER, P. & ROSEN, B. R.,
1991. Foramen magnum choroid plexus papilloma with drop metastases to the lumbar spine. American Journal of Neuroradiology, 12, 564-565. FORD, W. J., BROOKS, B. S., GAMMAL, T. & MASSEY, C. E.,
1988. Adult cerebellopontine MR evaluation. papilloma: Neuroradiology, 9, 611.
angle choroid plexus American Journal of
MARTIN, N., PIEROT, L., STERKERS, O., MOMPOINT, D. &
NAHUM, H., 1990. Primary choroid plexus papilloma of the
VoL 65, No. 777
cerebellopontine angle: MR imaging. Neuroradiology, 31, 541-543. NAGUIB, M. G., CHOU, S. N. & MASTRI, A., 1981. Radiation
therapy of a choroid plexus papilloma of the cerebellopontine angle with bone involvement. Journal of Neurosurgery, 54, 245-247. PlCARD,
C,
COPTY,
M.,
LAVOIE,
G.,
MlCHAUD,
J.
&
BOUCHARD, R., 1979. A primary choroid plexus papilloma of the cerebellopontine angle. Surgical Neurology, 12, 123-127. ROVIT,
R. L.,
SCHECTER,
M. M.
& CHODROFF, P.,
1970.
Choroid plexus papillomas: observations on radiographic diagnosis. American Journal of Roentgenology, 110, 608-617. RUSSELL,
D. S. & RUBENSTEIN,
L. J.,
1971. Pathology
of
Tumours of the Nervous System (Edward Arnold, London), p. 163. ZIMMERMAN, R. D., FLEMING, C. A., SAINT LOUIS, L. A., LEE, B. C. P., MANNING, J. J. & DECK, M. D. F., 1985. Magnetic
resonance imaging of meningiomas. American Journal of Neuroradiology, 6, 149-157.
757
