Progress in neurological surgery

Publications in this journal

• Article: Pineal germ cell tumors.

  Masao Matsutani
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  ABSTRACT: Intracranial germ cell tumors (GCTs), especially pineal tumors have attracted the special attention of neuropathologists and neurosurgeons because of their unique growth sites, characteristic subtypes with different histology, and high incidence in Japan and other Asian countries. This chapter describes the general clinical features of pineal GCTs and current treatment of intracranial GCTs. Despite excellent long-term results for patients with germinoma treated with radiation therapy, the potential for late effects makes the treatment controversial. Most patients with nongerminomatous tumors treated by conventional treatment with surgery and radiation therapy failed to survive longer than 3 years. After combination chemotherapy with cisplatin was confirmed to be effective in gonadal GCTs, GCTs of the brain became candidates for chemotherapy. For germinoma, a trial with chemotherapy alone failed with a high rate of recurrence, but Japanese and European trials with chemotherapy and reduced dose and volume of radiation therapy demonstrate good event-free survival rates. Ongoing phase II studies with combined chemotherapy and radiation therapy for nongerminomatous tumors will result in a 5-year survival rate of >50%, which is better than that by radiation therapy alone.
  Progress in neurological surgery 02/2009; 23:76-85.
• Article: Radiosurgery for intracranial gliomas.

  Yoshihisa Kida, Masayuki Yoshimoto, Toshinori Hasegawa
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  ABSTRACT: Long-term results of radiosurgery for GI to GIV astrocytomas are described. We have treated 172 astrocytoma cases in total, including 25 GI cases, 52 GII cases, 41 GIII cases and 54 GIV astrocytoma cases. There were 81 males and 91 females, with a mean age of 14.8 for GI, 33 for GII, 45.8 for GIII and 52.4 years for GIV. The maximum and marginal doses for GI astrocytomas were significantly lower than those for the other three grades due to their proximity to the optic nerves. GII to GIV tumors were treated with an approximately 30 Gy mean maximum dose and a 15-Gy mean marginal dose. The response rate of GI tumors exceeded 35%, while that of GII was 50%. However, the response rates of GIII and GIV astrocytomas were very low. Likewise, the tumor control rates were very high for GI and GII tumors, and were very low for GIII and GIV tumors. These results suggest differences in tumor infiltration and malignant activity at the periphery, and indicate the high efficacy of radiosurgery as well as its limitations.
  Progress in neurological surgery 02/2009; 22:122-8.
• Article: Radiosurgery for dural arteriovenous fistula.

  Yoshihisa Kida
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  ABSTRACT: The early results of radiosurgery for dural arteriovenous fistula (DAVF) are reported. Thirteen cases of DAVF, 9 males and 4 females, ranging in age from 39 to 74 years (mean 54.3), are presented. None underwent surgical resection, but 7 of the 13 did receive embolization. DAVF locations were the cavernous sinus (4), transverse-sigmoid (2), tentorium (4), and the anterior skull base, cranio-cervical junction, and superior sagittal sinus in 1 case each. The DAVF lesions were 14.9 mm in mean diameter and were treated with a mean marginal dose of 18.9 Gy (range 15-24 Gy). Follow-up studies (mean, 24 months) showed excellent neurological recovery as well as disappearance or shrinkage of the DAVF nidus. In conclusion, DAVF showed a remarkable response similar to that for AVM radiosurgery.
  Progress in neurological surgery 02/2009; 22:38-44.
• Article: Trigeminal neuralgia.

  Motohiro Hayashi
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  ABSTRACT: We completed a retrospective study of 270 patients with essential trigeminal neuralgia treated by gamma knife surgery. The target was localized on the retro-Gasserian portion of the nerve with 90 Gy at maximum. Among them, 150 patients were followed up more than 2 years. They were divided into 2 groups: pre-APS (41 patients) and post-APS (109 patients) treated by model C-APS since 2003. In the post-APS group, initial electric discharge was observed in 98.2% and at the last follow-up of at least 2 years in 79.8%. Complete recurrence was observed in 4.7% and postoperative complications were observed in 29.4%. These results were much better than those of the pre-APS group. There is no doubt that precise dose planning, C-APS treatment, so-called 'robotized micro radiosurgery', is important for improved treatment results.
  Progress in neurological surgery 02/2009; 22:182-90.
• Article: Long-term results of stereotactic gamma knife radiosurgery for pituitary adenomas. Specific strategies for different types of adenoma.

  Tatsuya Kobayashi
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  ABSTRACT: Long-term results of gamma knife radiosurgery for pituitary adenomas are presented and treatment strategies for different adenoma types are discussed. Two hundred and sixty-seven patients with pituitary adenoma have been treated by gamma knife radiosurgery during the past 12 years. There were 131 cases of nonfunctioning and 136 cases of functioning adenomas, in which 71 GH-producing, 33 PRL-producing and 32 ACTH-producing adenomas were included. Retreatment with the gamma knife was done in 8 cases because of large tumors or uncontrolled hormones. Micro- and small adenomas could be cured by gamma knife radiosurgery alone. Surgical or chemical debulking was necessary before radiosurgery for a large tumor with extrasellar extension. Retreatment was effective and safe in some cases. Nonfunctioning adenomas showed higher control rates than functioning adenomas even with lower dose treatment. Cushing disease showed the best response because of the smallest tumor size with the highest dose treatment. Acromegaly and prolactinoma were difficult to control because of larger tumors with lower dose treatment. The rate of hormone normalization was also high in Cushing disease but lower in prolactinoma and lowest in acromegaly. High-dose treatment was necessary for functioning adenomas to control tumor growth and oversecretion of hormones. In conclusion, gamma knife radiosurgery was effective and safe for the treatment of pituitary adenomas. However, the treatment strategies should be specific to each adenoma type according to the radiosensitivity, chemosensitivity and biological nature of the tumor.
  Progress in neurological surgery 02/2009; 22:77-95.
• Article: Gamma knife radiosurgery for skull-base meningiomas.

  Masami Takanashi, Seiji Fukuoka, Atsufumi Hojyo, Takehiko Sasaki, Jyoji Nakagawara, Hirohiko Nakamura
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  ABSTRACT: The primary purpose of this study was to evaluate the efficacy of gamma knife radiosurgery (GKRS) when used as a treatment modality for cavernous sinus or posterior fossa skull-base meningiomas (SBMs), with particular attention given to whether or not intentional partial resection followed by GKRS constitutes an appropriate combination treatment method for larger SBMs. Of the 101 SBM patients in this series, 38 were classified as having cavernous sinus meningiomas (CSMs), and 63 presented with posterior fossa meningiomas (PFMs). The patients with no history of prior surgery (19 CSMs, 57 PFMs) were treated according to a set protocol. Small to medium-sized SBMs were treated by GKRS only. To minimize the risk of functional deficits, larger tumors were treated with the combination of intentional partial resection followed by GKRS. Residual or recurrent tumors in patients who had undergone extirpations prior to GKRS (19 CSMs, 6 PFMs) are not eligible for this treatment method (due to the surgeries not being performed as part of a combination strategy designed to preserve neurological function as the first priority). The mean follow-up period was 51.9 months (range, 6-144 months). The overall tumor control rates were 95.5% in CSMs and 98.4% in PFMs. Nearly all tumors treated with GKRS alone were well controlled and the patients had no deficits. Furthermore, none of the patients who had undergone prior surgeries experienced new neurological deficits after GKRS. While new neurological deficits appeared far less often in those receiving the combination of partial resection with subsequent GKRS, extirpations tended to be associated with not only a higher incidence of new deficits but also a significant increase in the worsening of already-existing deficits. Our results indicate that GKRS is a safe and effective primary treatment for SBMs with small to moderate tumor volumes. We also found that larger SBMs compressing the optic pathway or brain stem can be effectively treated, minimizing any possible functional damage, by a combination of partial resection with subsequent GKRS.
  Progress in neurological surgery 02/2009; 22:96-111.
• Article: Pathology of intracranial germ cell tumors.

  Kazufumi Sato, Hiroaki Takeuchi, Toshihiko Kubota
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  ABSTRACT: Intra cranial germ cell tumors (GCTs) usually arise in midline structures, including the pineal or suprasellar regions of children and young adults. The classification of GCTs includes germinoma, teratoma, yolk sac tumor, embryonal carcinoma, and choriocarcinoma. However, intracranial GCTs are often of mixed histologic composition (mixed GCTs), and only germinoma and teratoma are likely to be encountered as pure tumor types. Although GCTs are usually identified using conventional histological techniques, immunohistochemical studies are very useful for delineating these entities, using special markers such as human chorionic gonadotropin, alpha-fetoprotein, human placental alkaline phosphatase, cytokeratin, as well as c-kit and OCT4. Ultrastructural examination is also useful in confirming the identity of these tumors. Genetic alterations specifically encountered in central nervous system GCTs are largely unknown. Patients with Klinefelter syndrome or Down syndrome appear to be predisposed to the development of gonadal as well as intracranial germinomas. Frequent imbalances of chromosomes have been described in intracranial GCTs, including chromosomes 1, 8, 12, 13, 18 and X. Recently, p14 and c-kit gene alterations have been reported, particularly in some intracranial germinomas; however, their importance remains unclear.
  Progress in neurological surgery 02/2009; 23:59-75.
• Article: Strategy of combined treatment of germ cell tumors.

  Yutaka Sawamura
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  ABSTRACT: The histopathological entity 'germ cell tumor' (GCT) encompasses a number of histological subtypes. Pineal GCTs can be grossly divided into three categories: those with a good, intermediate, and poor prognostic. Germinoma and mature teratoma are curable and classified into the good prognostic group, whereas embryonal carcinoma, yolk sac tumor, and other highly malignant neoplasms leave patients with a dismal prognosis. There are other types of GCT that have an intermediate prognosis, such as immature teratoma. Only mature teratomas are curable by surgical resection alone; the other types require adjuvant therapy. To plan a surgical strategy, then eurosurgeon has to acquire enough knowledge of the effect of adjuvant therapies and biological behavior of the GCTs. Germinoma can be cured by low-dose radiotherapy in combination with chemotherapy, and nowadays needs only to be biopsied. Other tumors, such as highly malignant tumors need a sophisticated combination therapy that includes surgery, craniospinal radiation therapy, and intensive chemotherapy. An appropriate neoadjuvant therapy prior toradical surgical removal will remarkably reduce the surgical risk. The goal of treatment should be tightly focused on the reduction of posttreatment sequelae, including surgical morbidity, and not on a complete microsurgical resection.
  Progress in neurological surgery 02/2009; 23:86-95.
• Article: Stereotactic radiosurgery for pineal and related tumors.

  Yoshimasa Mori, Tatsuya Kobayashi, Toshinori Hasegawa, Kouta Yoshida, Yoshihisa Kida
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  ABSTRACT: Radiosurgery is increasingly being used to treat pineal region tumors, either as an additional therapy after conventional treatments or as a primary treatment. We report our experience with Gamma Knife radiosurgery (GKRS) for the treatment of pineal and related tumors. Forty-nine patients underwent GKRS for pineal and related tumors (n = 74) between February 1992 and September 2007. The diagnosis was germ cell tumors (GCTs) in 38 patients (53 tumors), pineal parenchymal tumors (PPTs) in 9 (19 tumors), and unknown in 2 (2 tumors). The mean treatment volume was 3.3 ml (range 0.1-22 ml) in GCT cases and 3.7 ml (range 0.3-23 ml) in PPT cases. Prescribed doses around 50% isodose line ranged from 9.9 to 25.7 Gy. One patient (one tumor) with pineocytoma was lost to follow-up. Median clinical and imaging follow-up in the remaining 48 cases was 33.5 months (range, 3-192 months). Survival rates at 5 years and 10 years after GKRS in GCT cases (n = 38) were both 68%. They were 100 and 67%, respectively, in PPT cases (n = 8). We evaluated the treatment results with categorization of GCT cases into 2 groups, i.e. germinoma (group 1), and germinoma with syncytiotrophoblastic giant cell and malignant GCT (group 2). PPT cases were also divided into 2 groups, i.e. pineocytoma (group 3) and pineoblastoma and mixed pineocytoma/pineoblastoma (group 4). Local tumor control (LTC) rates at 3 and 5 years were 82% in group 1 (n = 18), 72 and 62% in group 2 (n = 35), and 85% in group 3 (n = 13). LTC rate at 2 years was 30% in group 4 (n = 5). In group 1 (n = 16), progression-free survival (PFS) rates at 3 and 5 years were 79 and 63%. They were 43 and 37% in group 2 (n = 22), and 80% in group 3 (n = 5). PFS rate at 2 years was 33% in group 4 (n = 3). Germinoma and pineocytoma showed higher LTC and PFS rates after GKRS, though pineoblastoma was liable to relapse. Intermediate prognosis was obtained in germinoma with syncytiotrophoblastic giant cell and malignant GCT. GKRS is expected to be an effective and safe adjuvant treatment approach to pineal and related tumors.
  Progress in neurological surgery 02/2009; 23:106-18.
• Article: Role of stereotactic radiosurgery in the management of pineal parenchymal tumors.

  Hideyuki Kano, Ajay Niranjan, Douglas Kondziolka, John C Flickinger, Dade Lunsford
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  ABSTRACT: We evaluated 20 pineal parenchymal tumor patients who underwent radiosurgery at our institution over a 20-year period. Thirteen patients had pineocytoma, 5 patients had pineoblastoma and 2 patients had mixed pineal parenchymal tumors. The median radiosurgery prescription dose to the tumor margin was 15.0 (12-20) Gy. At an average of 54.1 (range, 7.7-149.2) months, 6 patients had died and 14 patients were living. The overall survival after radiosurgery was 95.0, 68.6, and 51.4% at 1, 5 and 10 years, respectively. Patients with pineocytomas had 1-, 3- and 5-year overall survivals of 100, 92.3 and 92.3%, respectively. In 19 patients who were evaluated with imaging, 5 (26%) demonstrated complete regression, 9 (47%) had partial regression, 2 (11%) had stable tumors and 2 (11%) showed local in-field progression. The progression-free survival after stereotactic radiosurgery for all type of pineal parenchymal tumors was 100, 89.2 and 89.2% at 1, 3, 5 years after radiosurgery, respectively. Stereotactic radiosurgery is an effective and safe alternative to the surgical resection of pineocytomas as well as part of multimodal therapy for more aggressive pineal parenchymal tumors.
  Progress in neurological surgery 02/2009; 23:44-58.
• Article: Gamma knife radiosurgery for other primary intra-axial tumors.

  Yoshiyasu Iwai, Kazuhiro Yamanaka
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  ABSTRACT: We report the usefulness of gamma knife radiosurgery for hemangioblastomas, hemangiopericytomas, germ cell tumors and pineal parenchymal tumors, and primary central nervous system lymphoma (PCNSL). In hemangioblastomas, small solid tumors can be treated very effectively. Hemangiopericytomas are still difficult to control due to their aggressiveness and metastasis to other organs. However, radiosurgery is a useful alternative to repeat craniotomy for recurrence. Radiosurgery is a reasonable option to control residual and recurrent germ cell tumors and pineoblastomas. Although the prognosis is poor for PCNSL patients, gamma knife radiosurgery, even with a relatively low tumor margin dose, is an effective treatment for controlling PCNSL.
  Progress in neurological surgery 02/2009; 22:129-41.
• Article: Dose selection for optimal treatment results and avoidance of complications.

  Hisato Nagano, Satoshi Nakayama, Takashi Shuto, Hiroyuki Asada, Shigeo Inomori
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  ABSTRACT: What is the optimal treatment for metastatic brain tumors (MBTs)? We present our experience with gamma knife (GK) treatments for patients with five or more MBTs. Our new formula for predicting patient survival time (ST), which was derived by combining tumor control probability (TCP) calculated by Colombo's formula and normal tissue complication probability (NTCP) estimated by Flickinger's integrated logistic formula, was also evaluated. ST=a*[(C-NTCP)*TCP]+b; a, b, C: const. Forty-one patients (23 male, 18 female) with more than five MBTs were treated between March 1992 and February 2000. The tumors originated in the lung in 15 cases, in the breast in 8. Four patients had previously undergone whole brain irradiation (WBI). Ten patients were given concomitant WBI. Thirteen patients had additional extracranial metastatic lesions. TCP and NTCP were calculated using Excel add-in software. Cox's proportional hazards model was used to evaluate correlations between certain variables and ST. The independent variables evaluated were patient factors (age in years and performance status), tumor factors (total volume and number of tumors in each patient), treatment factors (TCP, NTCP and marginal dose) and the values of (C-NTCP)*TCP. Total tumor number was 403 (median 7, range 5-56). The median total tumor volume was 9.8 cm3 (range 0.8-111.8 cm3). The marginal dose ranged from 8 to 22 Gy (median 16.0Gy), TCP from 0.0% to 83% (median 15%) and NTCP from 0.0% to 31% (median 6.0%). (0.39-NTCP)*TCP ranged from 0.0 to 0.21 (median 0.055). Follow-up was 0.2 to 26.2 months, with a median of 5.4 months. Multiple-sample tests revealed no differences in STs among patients with MBTs of different origins (p=0.50). The 50% STs of patients with MBTs originating from the breast, lung and other sites were 5.9, 7.8 and 3.5 months, respectively. Only TCP and (0.39-NTCP)*TCP were statistically significant covariates (p=0.014, 0.001, respectively), and the latter was a more important predictor of ST than the former (Beta= -2.2, -14.1, respectively). The relationship between (0.39-NTCP)*TCP and ST was significant. Linear regression analysis showed this value to predict ST (p=0.002, R2=0.22). The slope of the regression line for patients with MBTs originating from the breast was steeper (a=218.2, p=0.08, R2=0.41) than the slopes of regression lines for patients with tumors of other origins (lung; a=56.8, p=0.004, R2=0.49, others; a=50.4, p=0.03, R2=0.25). In treating multiple lesions, the maximum doses and dose distribution for individual lesions were often different. The formula described by Colombo is used to calculate the residual clonogenic cell number of every sub-volume of the tumor, with different doses. NTCP must also integrate every complication probability for each sub-volume of normal brain tissue in the relatively high dose area in proximity to the tumor. Herein, we present a method for determining the irradiation dose necessary for cases with multiple brain metastases. A personal computer-aided calculation is employed.
  Progress in neurological surgery 02/2009; 22:11-9.
• Article: Gamma knife radiosurgery for brain metastases of non-lung cancer origin: focusing on multiple brain lesions.

  Masaaki Yamamoto, Bierta E Barfod, Yoichi Urakawa
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  ABSTRACT: We describe postradiosurgical treatment outcomes of our consecutive series of 456 patients (220 females, 236 males, mean age; 60.5 years, range 19-86 years) who underwent gamma knife (GK) treatment for brain metastases originating from non-lung cancers, focusing particularly on GK treatment for multiple lesions. The most common primary cancers were breast (122; 26.8%), followed by lower alimentary tract (105; 23.0%), uro-genital (100; 21.9%), upper alimentary tract (56; 12.3%), others (41; 9.0%) and unknown (32; 7.0%). Mean and median tumor numbers were 6 and 2, respectively, range 1-55. The mean and median survival times were 12.7 and 7.0 months after GK radiosurgery. Postradiosurgical survival rates were 52.7% at 6, 29.0% at 12, 19.1% at 18, 13.5% at 24, 6.5% at 36 and 5.0% at 60 months. Number of lesions, maximum and cumulative tumor volumes, non-symptomatic, well-controlled primary tumors, no non-brain metastatic lesions, Karnofsky performance status better than 80%, having prior surgery and having at least two procedures were significant predictive factors for survival. Although tumor number was demonstrated to have a significant impact on the duration of survival, approximately 85% of patients with brain metastases died of causes other than brain disease progression, regardless of tumor number.
  Progress in neurological surgery 02/2009; 22:154-69.
• Article: History and present status of gamma knife radiosurgery in Japan.

  Stephen Otto
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  ABSTRACT: The Leksell GammaKnife has been received well by the medical community since its introduction at Tokyo University Hospital in late 1989. Knowledgeable users, working with the Elekta Company and with foreign GammaKnife users, have contributed to this success. The original indications have grown as Japanese users--again along with their foreign compatriots--found new ways to combat intracranial diseases using the GammaKnife.
  Progress in neurological surgery 02/2009; 22:1-10.
• Article: Treatment of functional disorders with gamma knife thalamotomy.

  Chihiro Ohye, Tohru Shibazaki
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  ABSTRACT: Gamma knife (GK) thalamotomy for functional disorders, primarily Parkinson disease and central pain, are described herein. The goal was to extend our present indications for selective thalamotomy. Our target for tremor surgery is about 45% of the thalamic length. Thus, this principle was applied to deciding the GK thalamotomy target. In most of our cases, the protocol was 130 Gy, delivered in one shot with a 4-mm collimator. The time courses of thalamic lesion changes and clinical improvement after irradiation were assessed. Thus, despite thalamic reaction changes being variable, we achieved a clinical success rate of approximately 80% with negligible complications.
  Progress in neurological surgery 02/2009; 22:170-81.
• Article: Statistical analysis of pineal tumors based on the data of Brain Tumor Registry of Japan.

  Soichiro Shibui, Kazuhiro Nomura
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  ABSTRACT: In this study, we present statistical analyses of pineal tumors based on the data from Brain Tumor Registry of Japan. The most frequent tumor in the pineal region was germinoma, and it accounted for 49.2% of all pineal tumors; it was followed by pineocytoma (8.5%), glioma (6.5%), pineoblastoma (5.1%), malignant teratoma (5.2%) and teratoma (5.1%). Germinoma is most frequent among patients between 10 and 19 years of age, and there are some patients aged >30 years; however, there are few patients with choriocarcinoma, embryonal carcinoma, and yolk sac tumor who are aged >30 years. Pineoblastoma is most frequent among patients under 5 years of age, while pineocytoma is evenly distributed in patients between 10 and 60 years of age. The 5-year survival rate of germinoma was 89.4%, while those of embryonal carcinoma, yolk sac tumor and choriocarcinoma were 35.3, 37.3 and 58.1%, respectively.
  Progress in neurological surgery 02/2009; 23:1-11.
• Article: Occipital transtentorial approach and combined treatments for pineal parenchymal tumors.

  Itaru Tsumanuma, Ryuichi Tanaka, Yukihiko Fujii
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  ABSTRACT: The deep-seated location of pineal parenchymal tumors (PPTs) and their associations with critical structures make their surgical resection technically challenging; further, the rarity of PPTs and repeated changes in their histopathological diagnostic criteria makes the study of their biological behavior and clinical outcomes difficult. Here, we describe the surgical techniques and results of an occipital transtentorial approach for PPTs together with the results in the clinicopathological study of PPTs. Since 1982, we have treated 93 patients with pineal region tumors, including 17 PPTs, with the occipital transtentorial approach using the lateral semiprone position. The infrasplenial approach is helpful in separating the internal cerebral veins from the tumor, particularly when the tumor is tightly adherent to the veins. Permanent homonymous hemianopsia occurred in 1 of the 17 patients with PPTs. Permanent ocular movement disorders were not encountered. Extensive removal of the tumor significantly prolongs survival at least in patients with pineocytomas and PPT of intermediate differentiation (PPTIMD). Despite extensive resection and adjuvant radiochemotherapy, the prognosis of the patients with pineoblastomas is extremely poor. Although the proliferative potentials of pineocytomas and PPTIMD were significantly lower than those of pineoblastomas, there was no such difference between pineocytomas and PPTIMD.
  Progress in neurological surgery 02/2009; 23:26-43.
• Article: Pathology of pineal parenchymal tumors.

  Kazufumi Sato, Toshihiko Kubota
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  ABSTRACT: Pinea l parenchymal tumors (PPTs) are neuroepithelial tumors that arise from pineocytes or their precursors. According to the currently revised WHO classification of tumors of the central nervous system, PPTs are subdivided into well-differentiated pineocytoma, poorly differentiated pineoblastoma, and PPT with intermediate differentiation (PPTID). Pineocytomas are slow-growing neoplasms composed of small mature cells resembling pineocytes. Large pineocytomatous rosettes are the most characteristic appearance. Pineoblastomas are the most primitive form and have a highly malignant biological behavior. PPTIDs show an intermediate histological grade of malignancy between pineocytomas and pineoblastomas. Immunohistochemically, PPTs are positive for several neuronal markers, including synaptophysin, neurofilaments, class III beta-tubulin, and chromogranin A. Photosensory differentiation is associated with immunoreactivity for retinal S-antigen and rhodopsin. Ultrastructurally, dense core vesicles and clear vesicles are present in both cytoplasm and cellular processes, the latter showing occasional synapse-like junctions. In some cases, ultrastructural evidence of photoreceptor differentiation, such as synaptic ribbons, microtubular sheaves, and cilia, is observed. Little is known about the genetics responsible for the development of PPTs. Several chromosomal abnormalities have been identified frequently in pineoblastomas and PPTIDs but less commonly in pineocytomas. Pineoblastomas are known to occur in patients with RB1 gene abnormalities, and these tumors also develop in patients with familial bilateral retinoblastomas (trilateral retinoblastoma syndrome). However, specific gene abnormalities involved in the tumorigenesis of PPTs have not been identified.
  Progress in neurological surgery 02/2009; 23:12-25.
• Article: Radiation therapy for intracranial germ cell tumors.

  Hidefumi Aoyama
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  ABSTRACT: Although radiation therapy (RT) is essential to the management of intracranial germ cell tumors, the ideal radiation dose and field remain controversial. For the treatment of germinoma, whole central nervous system radiation, which was once the standard RT field, is being replaced by whole ventricle (WV) field radiation for localized disease. The use of induction chemotherapy has been expected to further reduce the RT field and dose; however, use of a localized field smaller than the WV field has resulted in a higher recurrence rate. Therefore, the WV field should be considered appropriate even after induction chemotherapy. With regard to the radiation dose to the primary tumor site, it can be reduced to 40-45 Gy in RT alone. The further reduction of the radiation dose when using a combination of chemotherapy and RT is yet to be determined. Unlike germinomas, nongerminomatous germ cell tumors, with the exception of mature teratomas, are refractory to conventional RT. The whole central nervous system field should thus be used for all but immature teratomas. Given that local progression is the primary pattern of recurrence even after effective induction chemotherapy, RT dose increase through the use of modern techniques, including stereotactic irradiation and intensity-modulated RT, should be investigated.
  Progress in neurological surgery 02/2009; 23:96-105.