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Malignant rhabdoid tumor of the central nervous system with subarachnoid dissemination
410
Surg Neurol 1992;37:410-4
Malignant Rhabdoid Tumor of the Central Nervous System with Subarachnoid Dissemination A.L. Agranovich, M.D., F.R.C.P.(C), L.-C. Ang, M.B., B.S., M.R.C.Path.(UK), F.R.C.P.(C), R.W. Griebel, M.D., F.R.C.S.(C), N.L. Kobrinsky, M.D., F.R.C.P.(C), N. Lowry, M.B., F.R.C.P.(C), and S.P. Tchang, M.D., F.R.C.P.(C) Departments of Radiation Oncology and Paediatric Oncology, Saskatoon Cancer Centre, Departments of Neuropathology, Neurusurgery, Paediatric Neurology, and Medical Imaging, Royal University Hospital, Saskatoon, Saskatchewan
Agranovich AL, Ang L-C, Griebel RW, Kobrinsky NL, Lowry N, Tchang SP. Malignant rhabdoid tumor of the central nervous system with subarachnoid dissemination. Surg Neurol 1992;37:410-4.
treatment on the clinical course and the pattern o f the recurrence of a primary M R T in the CNS.
Case R e p o r t A case of primary central nervous system malignant rhabdoid tumor is presented. Clinical, radiological, and histopathological findings are described in detail. Because of a relatively long clinical course after presentation, it was possible to assess the clinical and radiological response to different treatment modalities: surgery, chemotherapy, and radiotherapy. Despite the complete clinical and radiological response that was achieved after subtotal excision, two cycles of chemotherapy, and high-dose radiotherapy, the tumor recurred within 4 months of completion of the treatment, with wide subarachnoid dissemination. Radiotherapy treatment of whole cranial axis is recommended. KEY WORDS: Primary central nervous system malignant rhabdoid tumor; Response to combined therapy; Recurrence pattern
Malignant rhabdoid t u m o r (MRT), or rhabdoid tumor (RT), was originally described as a distinctive highly aggressive neoplasm of the infant kidney in 1978 [1]. Later on a few cases of extrarenal rhabdoid tumor (ERRT) were reported [ 7 - 9 ] . T h e r e were only few reports of primary M R T of the central nervous system (CNS) [2,4,5] and they described mainly the pathological features of the tumor. We decided to report this case because there are only a few reports that provide information about the effect of
Address reprint requests to: A.L. Agranovich, Department of Radiation Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 4H4. Received May 17, 1991; accepted November 6, 1991.
© 1992 by Elsevier Science Publishing Co., Inc.
A Native American boy, 2 years 9 months old, whose developmental milestones were normal, presented with acute onset of abnormal gait, thigh pain, vomiting, and lethargy. An initial neurological examination and all laboratory investigations, including lumbar puncture, showed no abnormalities. T h e symptoms spontaneously subsided within 3 days and the child was discharged, but 4 weeks later he was readmitted with lethargy, vomiting, and right arm weakness. At this time a neurological examination revealed bilateral papilledema, mild right facial weakness, and profound weakness of right upper and lower extremity. A computed tomography (CT) scan showed a large nonhomogeneously enhancing mass, deeply situated in the left hemisphere (Figure i). T h e child underwent craniotomy and subtotal excision of the t u m o r with small residual tumor remaining adjacent to the frontal horn o f the left lateral ventricle (Figure 2). At the time of surgery, the t u m o r was described as extremely vascular with cystic areas alternated with firm, solid areas. Light microscopy with hematoxylin and eosin stain revealed a t u m o r with trabecular arrangement characterized by large vesicular nuclei, p r o m i n e n t nucleoli, and abundant eosinophilic cytoplasm. Frequently the eosinophilic cytoplasm condensed into hyaline inclusions that indented or pushed the nuclei to one side (Figure 3). In some foci there were t u m o r cells with clear cytoplasm and centrally placed nuclei. While most of the tumor is quite cohesive, there were loose areas with tumor cells trapped in a m o r e myxoid background (Figure 4). A moderate degree of cellular p l e o m o r p h i s m and a high mitotic index were noted in the cellular areas of the tumor. N o H o m e r - W r i g h t or perivascular rosettes 0090-3019/92/$5.00
Malignant Rhabdoid Tumor of CNS
Surg Neurol 1992;37:410-4
411
Postsurgical treatment included two cycles of chemotherapy: cis-plastinum 90 mg/m ~ on day 1 and continuous infusion of adriamycin 20 mg/m~/day for 4 days. A C T scan performed after two cycles of chemotherapy showed again a small amount of residual disease adjacent to the frontal horn of the left lateral ventricle. The chemotherapy was followed by a course of external beam irradiation. The initial treatment volume included the preoperative tumor volume plus a 3 cm margin, treated to the total dose of 5000 cGy in 26 daily fractions, using lateral parallel pair technique. This was followed by an additional 500 cGy in three fractions, delivered to the preoperative tumor volume with a 1 cm margin, so the total dose to the tumor was 5500 cGy delivered in 29 fractions. Following radiotherapy, the patient's neurological status continued to improve, and his gait returned to almost normal. A C T scan, performed 6 weeks following irradiation, showed complete disappearance of enhancing tissue, which was compatible with complete response. Four months (17 weeks) following completion of radiotherapy, and 8 months after the initial diagnosis was made, the patient was readmitted to the hospital with
Figure 1. Enhanced C T scan at the time of presentation.
were seen. Highly vascular areas containing ectatic vessels were also seen. This tumor could be seen infiltrating into the surrounding brain. Immunohistochemical stains showed strong cytoplasmic immunoreactivity with antivimentin antibody especially in the cells with the so-called hyaline inclusions. Tumor cells also expressed neuron-specific enolase and glial fibrillary acidic protein in many areas. Ultrastructurally the most striking feature was found in cells with eccentric nuclei that contained whorls packed with intermediate filaments approximately 8-10 nm in width (Figure 5). Occasional tubulovesicular profiles, endoplasmic reticulum, and mitochondria could be seen within the filamentous deposits. The pathological features of this tumor were diagnostic of an MRT. Postoperatively the patient had only mild right-sided weakness and was able to walk. The work-up in the postoperative period included complete blood work, chest x-ray film, CT scan of the abdomen with special attention to the kidneys, bone scan, cerebrospinal fluid cytology, complete myelogram, and CT scan of the spine following the myelogram. None of these tests showed any abnormality.
Figure 2. Enhanced C T scan after craniotomy and tumor excision. Note subdural fluid collection related to surgery.
412
Surg Neurol 1992;37:410-4
Agranovich et al
pathological category as R T K or is a collection of histogenetically different tumors that share similar phenotypic manifestations [10]. The controversy has largely resulted from the uncertainty about the cell o f origin o f the tumor and the extreme rarity o f ERRT. If ERRT is a rare disease, a primary ERRT of the CNS is even more unusual. Only a handful o f reports are found in the medical literature. The issue is complicated by the observed association of RTK with embryonal primary tumor o f CNS [3]. One should notice, however, that in all seven cases described by Bonnin et al [3] the second CNS neoplasm was distinctly different histologically from R T K and usually represented a well-known CNS malignancy of childhood, such as medulloblastoma, pineoblastoma, and so on. The light microscopic features in our case, supported by immunohistochemical and ultrastructural studies, are characeristic of MRT. In our case we are apparently dealing with ERRT confined to the CNS, as the clinical, laboratory, and thorough radiological investigations failed to reveal any tumors outside the CNS and particularly in the kidney.
Figure 4. An area where the tumor cells are trapped in a loose and myxoid stroma (hematoxyHn and eosin x 180). Figure 3. Tumor is characterized by cells with vesicular nuclei, prominent. nucleoli and abundant eosinophilic cytoplasm pushing the nuclei aside (hematoxylin and eosin x 350J.
acute onset of a headache, projectile vomiting, and irritability. A neurological examination revealed no gross abnormalities, but a CT scan now revealed enhancing mass in either cerebellopontine angle, and adjacent to the temporal horn of the left lateral ventricle, which was compatible with widespread subarachnoid dissemination (Figure 6). Interestingly enough, there were only minimal, if any, changes in the primary site (anterior horn of the left lateral ventricle) (Figure 7). At this point further investigations and palliative treatment were offered, but they were refused by the patient's parents, and only compassionate care was carried on. The patient expired and, in accordance with the parents' wishes, no autopsy was performed.
Discussion Though rhabdoid tumor of kidney (RTK) is being considered as a distinct clinicopathological entity [8,11], it is still unclear whether ERRT represents the same
Malignant Rhabdoid Tumor of CNS
Surg Neurol 1992;37:410-4
413
Although an autopsy was not performed, there is nothing in the clinical course to suggest that the patient might have had another focus of malignancy, apart from the CNS tumor. T h e r e f o r e we believe that this case truly represents the extremely rare primary RT of the CNS. This case proves to be particularly valuable because we were able to follow the course of the disease over a relatively long period of time: almost 1 year. Apart from a case reported by Jakate et al [6] and one of the cases reported by Chou and Anderson [5] the clinical course has been very short [2,4], and thus authors concentrated on diagnostic aspects rather than clinical course of the tumor. We were also able to observe the response to different therapeutic modalities. We noted that chemotherapy was not effective in inducing radiological remission, although it may have prevented progression of the tumor over the period of 2 months. Radiotherapy had a definite impact on the tumor in inducing local radiological response. There was also some improvement of the neurological functions after the radiotherapy, which is harder to assess objectively.
Figure 5. Electron micrograph showing a tumor cell with cytoplasm packed with intermediate filaments. Tubulovesieular profiles, endoplasmic reticulum, and mitochondria are ako seen within the filamentous deposit ( × 18.000).
Figure 6. Enhanced C T scan at the time of the recurrence, shouing widespread subaraehnoid dissemination. Therefore this tumor is probably responsive to highdose external-beam radiation. The optimal dose of radiation, however, has yet to be established for this tumor. We found only one description of radiotherapy for MRT given by Chou and Anderson [5]. In that case an 18month-old child received 3600 cGy over 4 weeks to the whole brain--a 1000-cGy boost over 1 i/2 weeks to the primary site (posterior fossa) and 2600 cGy over 3 weeks to the spinal axis. Despite that, an autopsy performed 4 months later reported the presence of residual tumor mass 1.0 cm in diameter in the primary site and also tumor seeding in the cerebellar and spinal leptomeninges. In the report ofJakate et al [6] the 3-year-old child had a 6-weeks course of radiation therapy to the head and spine and was alive 5 months after the treatment. Unfortunately, no details of the doses and fractionation were given in that report. We can only assume, on the basis of experience with other highly aggressive primary CNS malignancies in childhood such as medulloblastoma and high-grade astrocytoma, that doses in the range of 5000 cGy and higher are necessary for local control of macroscopic residual disease.
414
Surg Neuroi 1992;37:410-4
Agranovich et al
mation of this in the autopsy case reported by Chou and Anderson [5]. We know from experience with such tumors as medulloblastoma, ependymoma, and primitive neuroectodermal tumors, that whole craniospinal axis irradiation is by far the most effective treatment in preventing CNS dissemination. While we are unable to make definite recommendations regarding management of this rare entity on the basis of a few cases, there is some suggestion that the volume of radiotherapy should include the entire craniospinal axis. We felt that our observations could be helpful for physicians who might encounter this uncommon malignancy. The authors thank Mrs. Gillian Hughes for excellent assistance in preparation of this manuscript.
References 1. BeckwithJB, Palmer NF. Histopathology and prognosis of Wilms' tumour. Cancer 1978;41:1937-48. 2. Biggs PJ, Garen PD, Powers JM. Malignant rhabdoid tumor of the CNS. Hum Pathol 1987;18:332-7. 3. BonninJM, Rubinstein LJ, Palmer NF, BeckwithJB. The association of embryonal tumors originating in the kidney and in the brain. Cancer 1984;54:2137-46. 4. Briner J, Bannwart F, Kleihues P. Malignant small cell tumor of the brain with intermediate filaments: a case of a primary cerebral rhabdoid tumor (abstract). Pediatr Pathol 1985;3:117-8. Figure 7. Enhanced C T scan at the time of recurrence. Primary site (see text). Also note the persistent fluid collection related to surgery.
The most interesting observation in this case was the pattern o f recurrence o f the tumor. As was pointed out, the tumor recurred in the subarachnoid space outside the radiotherapy treatment field. Unfortunately, we do not have histopathological confirmation regarding the status o f the primary site after radiotherapy, but a careful review of the CT scan with a neuroradiologist indicated that the recurrence affected the portion o f the brain and subarachnoid space outside the volume treated with radiotherapy. It appears likely that we are dealing with one of the C N S malignancies that have a strong tendency to disseminate throughout the CNS. There is additional confir-
5. Chou SM, AndersonJS. Primary CNS malignant rhabdoid tumor (MRT); report of two cases and review of literature. Clin Neuropathol 1991;10:1-10. 6. Jakate SM, Marsden HB, Ingram L. Primary rhabdoid tumour of the brain. Virchows Archiv A Pathol Anat Histopathol 1988;412:393-7. 7. Lynch HT, Shurin SB, Dahms BB, et al. Paravertebral malignant rhabdoid tumor in infancy: in vitro studies of a familial tumor. Cancer 1983;52:290. 8. Tsokos M, Gregory K, Roma SC, et al. Malignant rhabdoid tumor of the kidney and soft tissues. Arch Pathol Lab Med 1989; 113:115-20. 9. Tsuneyoshi M, Daimaru T, Hashimoto H, et al. Malignant soft tissue neoplasms with the histologic features of renal rhabdoid tumors: an ultrastructural and immunohistochemical study. Hum Pathol 1985;16:1235. 10. Weeks DA, BeckwithJB, Mierau GW. Rhabdoid tumor: an entity or a phenotype? Arch Pathol Lab Med 1989;113:113-4. 1 I. Weeks DA, Beckwith JB, Mierau GW, et al. Rhabdoid tumor of kidney. Am J Surg Pathol 1989;13:439-58.
Surg Neurol 1992;37:410-4
Malignant Rhabdoid Tumor of the Central Nervous System with Subarachnoid Dissemination A.L. Agranovich, M.D., F.R.C.P.(C), L.-C. Ang, M.B., B.S., M.R.C.Path.(UK), F.R.C.P.(C), R.W. Griebel, M.D., F.R.C.S.(C), N.L. Kobrinsky, M.D., F.R.C.P.(C), N. Lowry, M.B., F.R.C.P.(C), and S.P. Tchang, M.D., F.R.C.P.(C) Departments of Radiation Oncology and Paediatric Oncology, Saskatoon Cancer Centre, Departments of Neuropathology, Neurusurgery, Paediatric Neurology, and Medical Imaging, Royal University Hospital, Saskatoon, Saskatchewan
Agranovich AL, Ang L-C, Griebel RW, Kobrinsky NL, Lowry N, Tchang SP. Malignant rhabdoid tumor of the central nervous system with subarachnoid dissemination. Surg Neurol 1992;37:410-4.
treatment on the clinical course and the pattern o f the recurrence of a primary M R T in the CNS.
Case R e p o r t A case of primary central nervous system malignant rhabdoid tumor is presented. Clinical, radiological, and histopathological findings are described in detail. Because of a relatively long clinical course after presentation, it was possible to assess the clinical and radiological response to different treatment modalities: surgery, chemotherapy, and radiotherapy. Despite the complete clinical and radiological response that was achieved after subtotal excision, two cycles of chemotherapy, and high-dose radiotherapy, the tumor recurred within 4 months of completion of the treatment, with wide subarachnoid dissemination. Radiotherapy treatment of whole cranial axis is recommended. KEY WORDS: Primary central nervous system malignant rhabdoid tumor; Response to combined therapy; Recurrence pattern
Malignant rhabdoid t u m o r (MRT), or rhabdoid tumor (RT), was originally described as a distinctive highly aggressive neoplasm of the infant kidney in 1978 [1]. Later on a few cases of extrarenal rhabdoid tumor (ERRT) were reported [ 7 - 9 ] . T h e r e were only few reports of primary M R T of the central nervous system (CNS) [2,4,5] and they described mainly the pathological features of the tumor. We decided to report this case because there are only a few reports that provide information about the effect of
Address reprint requests to: A.L. Agranovich, Department of Radiation Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 4H4. Received May 17, 1991; accepted November 6, 1991.
© 1992 by Elsevier Science Publishing Co., Inc.
A Native American boy, 2 years 9 months old, whose developmental milestones were normal, presented with acute onset of abnormal gait, thigh pain, vomiting, and lethargy. An initial neurological examination and all laboratory investigations, including lumbar puncture, showed no abnormalities. T h e symptoms spontaneously subsided within 3 days and the child was discharged, but 4 weeks later he was readmitted with lethargy, vomiting, and right arm weakness. At this time a neurological examination revealed bilateral papilledema, mild right facial weakness, and profound weakness of right upper and lower extremity. A computed tomography (CT) scan showed a large nonhomogeneously enhancing mass, deeply situated in the left hemisphere (Figure i). T h e child underwent craniotomy and subtotal excision of the t u m o r with small residual tumor remaining adjacent to the frontal horn o f the left lateral ventricle (Figure 2). At the time of surgery, the t u m o r was described as extremely vascular with cystic areas alternated with firm, solid areas. Light microscopy with hematoxylin and eosin stain revealed a t u m o r with trabecular arrangement characterized by large vesicular nuclei, p r o m i n e n t nucleoli, and abundant eosinophilic cytoplasm. Frequently the eosinophilic cytoplasm condensed into hyaline inclusions that indented or pushed the nuclei to one side (Figure 3). In some foci there were t u m o r cells with clear cytoplasm and centrally placed nuclei. While most of the tumor is quite cohesive, there were loose areas with tumor cells trapped in a m o r e myxoid background (Figure 4). A moderate degree of cellular p l e o m o r p h i s m and a high mitotic index were noted in the cellular areas of the tumor. N o H o m e r - W r i g h t or perivascular rosettes 0090-3019/92/$5.00
Malignant Rhabdoid Tumor of CNS
Surg Neurol 1992;37:410-4
411
Postsurgical treatment included two cycles of chemotherapy: cis-plastinum 90 mg/m ~ on day 1 and continuous infusion of adriamycin 20 mg/m~/day for 4 days. A C T scan performed after two cycles of chemotherapy showed again a small amount of residual disease adjacent to the frontal horn of the left lateral ventricle. The chemotherapy was followed by a course of external beam irradiation. The initial treatment volume included the preoperative tumor volume plus a 3 cm margin, treated to the total dose of 5000 cGy in 26 daily fractions, using lateral parallel pair technique. This was followed by an additional 500 cGy in three fractions, delivered to the preoperative tumor volume with a 1 cm margin, so the total dose to the tumor was 5500 cGy delivered in 29 fractions. Following radiotherapy, the patient's neurological status continued to improve, and his gait returned to almost normal. A C T scan, performed 6 weeks following irradiation, showed complete disappearance of enhancing tissue, which was compatible with complete response. Four months (17 weeks) following completion of radiotherapy, and 8 months after the initial diagnosis was made, the patient was readmitted to the hospital with
Figure 1. Enhanced C T scan at the time of presentation.
were seen. Highly vascular areas containing ectatic vessels were also seen. This tumor could be seen infiltrating into the surrounding brain. Immunohistochemical stains showed strong cytoplasmic immunoreactivity with antivimentin antibody especially in the cells with the so-called hyaline inclusions. Tumor cells also expressed neuron-specific enolase and glial fibrillary acidic protein in many areas. Ultrastructurally the most striking feature was found in cells with eccentric nuclei that contained whorls packed with intermediate filaments approximately 8-10 nm in width (Figure 5). Occasional tubulovesicular profiles, endoplasmic reticulum, and mitochondria could be seen within the filamentous deposits. The pathological features of this tumor were diagnostic of an MRT. Postoperatively the patient had only mild right-sided weakness and was able to walk. The work-up in the postoperative period included complete blood work, chest x-ray film, CT scan of the abdomen with special attention to the kidneys, bone scan, cerebrospinal fluid cytology, complete myelogram, and CT scan of the spine following the myelogram. None of these tests showed any abnormality.
Figure 2. Enhanced C T scan after craniotomy and tumor excision. Note subdural fluid collection related to surgery.
412
Surg Neurol 1992;37:410-4
Agranovich et al
pathological category as R T K or is a collection of histogenetically different tumors that share similar phenotypic manifestations [10]. The controversy has largely resulted from the uncertainty about the cell o f origin o f the tumor and the extreme rarity o f ERRT. If ERRT is a rare disease, a primary ERRT of the CNS is even more unusual. Only a handful o f reports are found in the medical literature. The issue is complicated by the observed association of RTK with embryonal primary tumor o f CNS [3]. One should notice, however, that in all seven cases described by Bonnin et al [3] the second CNS neoplasm was distinctly different histologically from R T K and usually represented a well-known CNS malignancy of childhood, such as medulloblastoma, pineoblastoma, and so on. The light microscopic features in our case, supported by immunohistochemical and ultrastructural studies, are characeristic of MRT. In our case we are apparently dealing with ERRT confined to the CNS, as the clinical, laboratory, and thorough radiological investigations failed to reveal any tumors outside the CNS and particularly in the kidney.
Figure 4. An area where the tumor cells are trapped in a loose and myxoid stroma (hematoxyHn and eosin x 180). Figure 3. Tumor is characterized by cells with vesicular nuclei, prominent. nucleoli and abundant eosinophilic cytoplasm pushing the nuclei aside (hematoxylin and eosin x 350J.
acute onset of a headache, projectile vomiting, and irritability. A neurological examination revealed no gross abnormalities, but a CT scan now revealed enhancing mass in either cerebellopontine angle, and adjacent to the temporal horn of the left lateral ventricle, which was compatible with widespread subarachnoid dissemination (Figure 6). Interestingly enough, there were only minimal, if any, changes in the primary site (anterior horn of the left lateral ventricle) (Figure 7). At this point further investigations and palliative treatment were offered, but they were refused by the patient's parents, and only compassionate care was carried on. The patient expired and, in accordance with the parents' wishes, no autopsy was performed.
Discussion Though rhabdoid tumor of kidney (RTK) is being considered as a distinct clinicopathological entity [8,11], it is still unclear whether ERRT represents the same
Malignant Rhabdoid Tumor of CNS
Surg Neurol 1992;37:410-4
413
Although an autopsy was not performed, there is nothing in the clinical course to suggest that the patient might have had another focus of malignancy, apart from the CNS tumor. T h e r e f o r e we believe that this case truly represents the extremely rare primary RT of the CNS. This case proves to be particularly valuable because we were able to follow the course of the disease over a relatively long period of time: almost 1 year. Apart from a case reported by Jakate et al [6] and one of the cases reported by Chou and Anderson [5] the clinical course has been very short [2,4], and thus authors concentrated on diagnostic aspects rather than clinical course of the tumor. We were also able to observe the response to different therapeutic modalities. We noted that chemotherapy was not effective in inducing radiological remission, although it may have prevented progression of the tumor over the period of 2 months. Radiotherapy had a definite impact on the tumor in inducing local radiological response. There was also some improvement of the neurological functions after the radiotherapy, which is harder to assess objectively.
Figure 5. Electron micrograph showing a tumor cell with cytoplasm packed with intermediate filaments. Tubulovesieular profiles, endoplasmic reticulum, and mitochondria are ako seen within the filamentous deposit ( × 18.000).
Figure 6. Enhanced C T scan at the time of the recurrence, shouing widespread subaraehnoid dissemination. Therefore this tumor is probably responsive to highdose external-beam radiation. The optimal dose of radiation, however, has yet to be established for this tumor. We found only one description of radiotherapy for MRT given by Chou and Anderson [5]. In that case an 18month-old child received 3600 cGy over 4 weeks to the whole brain--a 1000-cGy boost over 1 i/2 weeks to the primary site (posterior fossa) and 2600 cGy over 3 weeks to the spinal axis. Despite that, an autopsy performed 4 months later reported the presence of residual tumor mass 1.0 cm in diameter in the primary site and also tumor seeding in the cerebellar and spinal leptomeninges. In the report ofJakate et al [6] the 3-year-old child had a 6-weeks course of radiation therapy to the head and spine and was alive 5 months after the treatment. Unfortunately, no details of the doses and fractionation were given in that report. We can only assume, on the basis of experience with other highly aggressive primary CNS malignancies in childhood such as medulloblastoma and high-grade astrocytoma, that doses in the range of 5000 cGy and higher are necessary for local control of macroscopic residual disease.
414
Surg Neuroi 1992;37:410-4
Agranovich et al
mation of this in the autopsy case reported by Chou and Anderson [5]. We know from experience with such tumors as medulloblastoma, ependymoma, and primitive neuroectodermal tumors, that whole craniospinal axis irradiation is by far the most effective treatment in preventing CNS dissemination. While we are unable to make definite recommendations regarding management of this rare entity on the basis of a few cases, there is some suggestion that the volume of radiotherapy should include the entire craniospinal axis. We felt that our observations could be helpful for physicians who might encounter this uncommon malignancy. The authors thank Mrs. Gillian Hughes for excellent assistance in preparation of this manuscript.
References 1. BeckwithJB, Palmer NF. Histopathology and prognosis of Wilms' tumour. Cancer 1978;41:1937-48. 2. Biggs PJ, Garen PD, Powers JM. Malignant rhabdoid tumor of the CNS. Hum Pathol 1987;18:332-7. 3. BonninJM, Rubinstein LJ, Palmer NF, BeckwithJB. The association of embryonal tumors originating in the kidney and in the brain. Cancer 1984;54:2137-46. 4. Briner J, Bannwart F, Kleihues P. Malignant small cell tumor of the brain with intermediate filaments: a case of a primary cerebral rhabdoid tumor (abstract). Pediatr Pathol 1985;3:117-8. Figure 7. Enhanced C T scan at the time of recurrence. Primary site (see text). Also note the persistent fluid collection related to surgery.
The most interesting observation in this case was the pattern o f recurrence o f the tumor. As was pointed out, the tumor recurred in the subarachnoid space outside the radiotherapy treatment field. Unfortunately, we do not have histopathological confirmation regarding the status o f the primary site after radiotherapy, but a careful review of the CT scan with a neuroradiologist indicated that the recurrence affected the portion o f the brain and subarachnoid space outside the volume treated with radiotherapy. It appears likely that we are dealing with one of the C N S malignancies that have a strong tendency to disseminate throughout the CNS. There is additional confir-
5. Chou SM, AndersonJS. Primary CNS malignant rhabdoid tumor (MRT); report of two cases and review of literature. Clin Neuropathol 1991;10:1-10. 6. Jakate SM, Marsden HB, Ingram L. Primary rhabdoid tumour of the brain. Virchows Archiv A Pathol Anat Histopathol 1988;412:393-7. 7. Lynch HT, Shurin SB, Dahms BB, et al. Paravertebral malignant rhabdoid tumor in infancy: in vitro studies of a familial tumor. Cancer 1983;52:290. 8. Tsokos M, Gregory K, Roma SC, et al. Malignant rhabdoid tumor of the kidney and soft tissues. Arch Pathol Lab Med 1989; 113:115-20. 9. Tsuneyoshi M, Daimaru T, Hashimoto H, et al. Malignant soft tissue neoplasms with the histologic features of renal rhabdoid tumors: an ultrastructural and immunohistochemical study. Hum Pathol 1985;16:1235. 10. Weeks DA, BeckwithJB, Mierau GW. Rhabdoid tumor: an entity or a phenotype? Arch Pathol Lab Med 1989;113:113-4. 1 I. Weeks DA, Beckwith JB, Mierau GW, et al. Rhabdoid tumor of kidney. Am J Surg Pathol 1989;13:439-58.