Tamio Ito

Careful exclusion of non-neoplastic brain components is required for an appropriate evaluation of O6-methylguanine-DNA methyltransferase status in glioma: relationship between immunohistochemistry and methylation analysis.

Evaluation of O6-methylguanine-DNA methyltransferase (MGMT) expression is important for antiglioma therapy as many clinical trials have demonstrated that promoter hypermethylation and low level expression of MGMT are associated with an enhanced response to alkylating agents. However, here we report that the current strategies used to evaluate MGMT status in gliomas are unreliable. We observed discordance in the MGMT expression status when immunohistochemical evaluation and polymerase chain reaction-based methylation assessments were used: 73% of gliomas with methylated MGMT promoter had substantial numbers of MGMT-immunopositive tumor cells. Furthermore, when MGMT expression was tested in tumor homogenates using reverse transcription-polymerase chain reaction, 43% of tumors were found positive, in comparison to only 24%, when histologic samples were assayed immunohistochemically. To explain these inconsistencies we undertook a detailed immunohistochemical evaluation of tumor samples and found that some gliomas demonstrated remarkably high expression of MGMT in the entire tumor whereas others contained only a small immunopositive area. Additionally, we found that gliomas contained various types of non-neoplastic cells expressing MGMT, including lymphocytes, vascular endothelial cells, and macrophages/microglias, which contribute to overall MGMT expression detected in tumor homogenates, and thus result in overestimation of tumor MGMT expression. Therefore, to correctly establish MGMT expression in the tumor, which could be informative of glioma sensitivity to alkylating agents, exclusion of non-neoplastic brain components from analysis is required.

Gamma Knife Radiosurgery for Growth Hormone-Secreting Pituitary Adenomas Invading the Cavernous Sinus

The authors assessed whether gamma knife radiosurgery is effective for patients with acromegaly where the pituitary tumors invaded the cavernous sinus. Radiosurgery was performed on 9 patients (average of 20 Gy to the tumor margin), 8 of whom had already undergone transsphenoidal surgery and/or craniotomy with occasional medication of octreotide to reduce tumor size as well as hormonal levels. All tumors have been well controlled so far with follow-up periods ranging from 12 to 69 months (mean: 42). No complications occurred. Forty percent of the patients showed hormonal normalization at 2 years, with the median being 31 months. Similarly, 50% of the patients demonstrated normalization of GH and IGF-I at 36 months. We conclude that gamma knife radiosurgery is a safe and effective tool to treat these tumors invading the cavernous sinus.

A case of cervicomedullary junction tanycytic ependymoma associated with marked cyst formation

Tanycytic ependymomas are a subtype of ependymomas that were formally recognized as a new pathological entity in the latest World Health Organization (WHO) classification of 2000. They occur mostly in the spinal cord. Only a few reports have analyzed the proliferative potentials of these tumors; however, it has been reported that the MIB-1 labeling index of tanycytic ependymoma is lower than that of other subtypes of WHO grade II ependymomas. We report a rare case of cervicomedullary junction tanycytic ependymoma associated with marked cyst formation. A 62-year-old man had a history of progressive gait disturbance, diplopia, and swallowing disturbance over a one-month period prior to admission. Magnetic resonance imaging (MRI) showed a cystic mass with a mural nodule at the cervicomedullary junction with Gd-DTPA enhancement. Cyst-subarachnoid shunt was performed using a far lateral approach. After 6 years, however, the man was readmitted to the hospital because of reaccumulation of the cyst. Partial removal of a mural nodule and a cyst-subarachnoid shunt were performed simultaneously by a midline suboccipital approach. The pathological diagnosis was tanycytic ependymoma. Postoperatively, the patient recovered well and was discharged from the hospital without further treatment. Most of the tumor cells had small, round nuclei; pleomorphism was minimal. The cytoplasm was dilated. The tumor cells were positive for EMA and s-100, and negative for CD-34. GFAP was not determined due to difficulty caused by background glial processes. The MIB-1 labeling index was less than 1%. Ultrastructurally, the tumor cells had ependymal cell features, such as desmosomes and microvilli. Based on these findings, the pathological diagnosis was tanycytic ependymoma.

Clinicopathologic Study of Pineal Parenchymal Tumors of Intermediate Differentiation

OBJECTIVE Pineal parenchymal tumors of intermediate differentiation (PPTID) are extremely rare tumor entities, and only limited data are available regarding their pathologic features and biologic behaviors. Because grading criteria of pineal parenchymal tumors (PPTs) have yet to be established, the treatment strategy and prognosis of PPTIDs remain controversial. We describe the clinicopathologic study of six patients with PPTID and compare responses for the treatment and prognosis with cases of pineocytoma (PC) and pineoblastoma (PB). From this analysis, we attempt to clarify the treatment strategy for PPTIDs. METHODS This study included 15 patients with PPTs, consisting of 6 PCs, 6 PPTIDs, and 3 PBs. We focused on the 6 patients with PPTIDs. All PPTID cases were treated surgically, and radiotherapy and chemotherapy were administered as adjuvant therapies in some cases. We have earlier reported the histopathologic study (Neuropathology 32:647-653, 2012). Briefly, we examined mitotic figures and necrosis by hematoxylin-eosin staining and immunohistochemical markers such as neuronal markers (synaptophysin, neurofilament (NF), and neuronal nuclear antigen), and an MIB-1 labeling index was determined. RESULTS In the PPTID cases, the extent of resection was variable and the recurrence rates among patients varied according to stage and treatment. All PC patients underwent total resection with no recurrence. All PB patients underwent resection and adjuvant therapy with radiotherapy and chemotherapy. There were no recurrences in patients with PC or PB. The results of histopathologic findings have been already reported as mentioned above. Briefly, the results indicated no mitotic figure or necrosis in any of the six cases of PPTID, but those features were observed in PB cases. All cases even including PC and PB were immunopositive for neuronal markers. The MIB-1 labeling index of PPTID was 3.5%, whereas it was 0% in PC and 10.5% in PB. CONCLUSIONS Good radiosensitivity of PPTIDs was observed in our series. Because there are cases with discrepancies between images and pathologic findings, it is very difficult to determine the proper treatment strategy for PPTIDs. Proliferative potential was correlated with World Health Organization grade, although the immunoreactivity of neuronal markers did not correlate with the histologic grade.

Immunohistochemical evaluation of O6‐methylguanine DNA methyltransferase (MGMT) expression in 117 cases of glioblastoma

Temozolomide (TMZ) is an oral alkylating agent which is widely used in the treatment of glioblastoma (GBM) and is composed of astrocytic and/or oligodendroglial tumors, and the evaluation of O6‐methylguanine DNA methyltransferase (MGMT) expression is important to predict the response to TMZ therapy. In this study, we conducted immunohistochemical analysis of 117 cases of Japanese GBM including 19 cases of GBM with oligodendroglioma component (GBMO), using a scoring system for quantitative evaluation of staining intensity and proportion of MGMT, and performed survival analysis of these patients. Immunohistochemically, 55 cases (47%) were positive for MGMT with various intensities and proportions (total score (TS) ≥ 2), while 62 cases (53%) were negative (TS = 0). The distribution of MGMT expression pattern was not affected by any clinicopathological parameters such as the histological subtype (GBM vs. GBMO), age and gender. The survival analysis of these patients revealed that the minimal expression of MGMT (TS ≥ 2) was a significant unfavorable prognostic factor (P < 0.001) as well as resectability (P = 0.004). Moreover, multivariate analysis showed that minimal MGMT expression in GBM was the most potent independent predictor for progression free survival (P < 0.001) and also overall patient survival (P < 0.001). This is the first report employing the scoring system for both staining intensity and proportion to evaluate immunohistochemical MGMT expression in GBM. In addition, our results emphases the clinicopathological values of the immunohistochemical approach for MGMT expression in glioma patients as a routine laboratory examination.

A case of tanycytic ependymoma arising from the cerebral hemisphere

We report a rare case of tanycytic ependymoma arising from the cerebral hemisphere. A 59-year-old man was admitted to our hospital because of the incidental detection by MRI of a tumor lesion in the right temporooccipital paratrigonal region. The mass showed low-to iso-intensity on T1-weighted images and high intensity on T2/proton-weighted images. Partial resection was performed using a transsulcal approach to avoid compromising the visual field. Most of the tumor cells showed elongated spindle shapes arranged in dense fascicles. A few true ependymal rosettes and perivascular pseudorosettes were visible. The tumor cells were positive for GFAP, S-100, and vimentin, but negative for synaptophysin, EMA, and keratin. The MIB-1 labeling index was approximately 1%. Ultrastructurally, the tumor cells had ependymal cell features, such as microvilli and cilia. From these findings, a pathological diagnosis of tanycytic ependymoma was made.

A case of cerebral ganglioneuronal tumor in the parietal lobe of an adult

Central nervous system (CNS) neuroblastoma/ganglioneuroblastoma is one of the embryonal tumors with neuronal differentiation found in young adults, but it is most common in children, especially in those below the age of 5 years, whereas extraventricular neurocytoma, a rare neuroepithelial tumor with neuronal differentiation, mostly affects young adults. Here we present a rare case of cerebral ganglioneuronal tumor that occurred in a 32-year-old woman. The patient suffered from tonic convulsion, and computed tomography demonstrated a well-demarcated, round tumor 3.3 cm in size with marked calcification in the right parietal lobe. Histological analysis revealed diffuse infiltration of small, round cells with scattered large ganglion-like cells. Immunohistochemically, the tumor cells did not react with any neuronal molecules, except for chromogranin A in ganglion-like large tumor cells, but electron microscopy demonstrated the presence of synapse-like nerve terminal structures without mature postsynaptic density, suggesting the presence of neoplastic tumor components with neuronal differentiation; thus, this tumor was diagnosed as CNS ganglioneuroblastoma with possible low-grade malignancy because the Mib-1 labeling index was less than 3%–4%. Here we discuss the histological entity of cerebral ganglioneuronal tumors, including extraventricular neurocytoma.

Radiation-induced osteosarcomas after treatment for frontal gliomas: a report of two cases.

Most radiation-induced osteosarcomas of the skull are reported to arise in the facial bone or paranasal sinus after radiotherapy for retinoblastoma and/or pituitary adenoma. Here we report two cases of radiation-induced osteosarcoma in the paranasal sinus after treatment for frontal glioma. Case 1 was a 56-year-old woman who underwent surgical resection of a left frontal tumor in October 1990. The histological diagnosis was a low-grade glioma, and radiotherapy of 54 Gy was administered. Sixteen years later, in September 2006, the patient noted an enlarging subcutaneous mass in the right frontal region. CT showed an osteolytic mass in the right frontal sinus. An open biopsy established the histopathological diagnosis of osteosarcoma, and the patient subsequently died of rapid tumor regrowth. Case 2 was a 58-year-old man who underwent partial removal of a bifrontal tumor in May 1996. The histological diagnosis was anaplastic oligoastrocytoma, and radiotherapy of 56 Gy was administered. Twelve years later, in March 2008, the patient was readmitted to our hospital for reasons of marked deterioration in general physical condition. Tumor recurrence was suspected in the left frontal lobe, and CT demonstrated an osteolytic mass in the left frontal and ethmoid sinus. A secondary operation was performed, and the pathological specimens were diagnosed as osteosarcoma. Radiotherapy was readministered, but the subject died of rapid tumor regrowth. From these clinicopathological findings, both cases were diagnosed as radiation-induced osteosarcoma. Radiation-induced osteosarcomas appeared 16 and 12 years after radiotherapy in cases 1 and 2, respectively. As the prognosis of radiationinduced osteosarcoma is poorer than that of primary osteo-sarcoma, careful attention is required for consideration of the long-term survival of patients with glioma.

[Clinicopathological Study of Pilomyxoid-Spectrum Astrocytomas:An Analysis of the BRAF Gene. Report of Two Cases].

In contrast to pilocytic astrocytomas(PAs), pilomyxoid astrocytomas(PMAs)demonstrate monophasic piloid cells with angiocentric distribution and a more aggressive clinical course. Recently, several reports have described combined histological features of both subtypes;accordingly, these were termed intermediate pilomyxoid tumors(IPTs). The KIAA1549-BRAF fusion gene has been found in approximately 70% of PAs, but is reportedly rare in PMAs. We describe a clinicopathological study of two patients with pilomyxoid-spectrum astrocytoma(PMSA). Case 1 was of a 29-year-old man who presented with a generalized seizure. Gadolinium-magnetic resonance imaging(Gd-MRI)demonstrated a less enhanced tumor in the left temporal lobe. Case 2 was of a 9-year-old boy who presented with headache. Gd-MRI revealed an irregularly enhanced tumor in the left cerebellum. In Case 1, the tumor showed monomorphous bipolar cells in a myxoid background and angiocentric arrangement;therefore, the diagnosis was PMA. In Case 2, part of the tumor had a myxoid, angiocentric pattern characteristic of PMA;the other part had a biphasic pattern characteristic of PA. PMA and PA were mixed in a 7:3 ratio;therefore, IPT was diagnosed. No BRAF V600E mutations were found by immunohistochemistry and sequencing in either case. Three major KIAA1549-BRAF fusion subtypes were analyzed by quantitative reverse transcription polymerase chain reaction(RT-PCR)and sequencing. No fusions were found in Case 1. However, K16-B9 fusion was identified in Case 2, and this fusion was more prevalent in the PA component than in the PMA component. In summary, no BRAF V600E mutations were found in PMSAs, but KIAA1549-BRAF fusion was identified in IPT, particularly in the PA component.

[Pineal Parenchymal Tumor with Marked Cytologic Pleomorphism: Is there a Correlation with the Malignancy Grade?].

INTRODUCTION In benign pineal parenchymal tumors (PPTs), namely, pineocytoma(PC)and PPT of intermediate differentiation (PPTID), cytologic pleomorphism has occasionally been found;however, it is controversial as to whether the presence of pleomorphic cells leads to upgrading of tumors. We experienced a rare case of pleomorphic PPT in an elderly woman and compared it with a retrospective series of 12 PPTs (PC:3, PPTID:6, pineoblastoma[PB]:3)to evaluate the correlation between pleomorphism and the malignancy grade. CASE AND MATERIALS: A 76-year-old woman presented with gradual cognitive deterioration and gait disturbance. Gadolinium-enhanced magnetic resonance imaging(Gd-MRI)revealed a small, enhanced tumor in the pineal gland with marked hydrocephalus. Endoscopic tumor biopsy and third ventriculostomy were performed simultaneously. The tumor was soft, pinkish, and slightly hemorrhagic. After the biopsy, the patient underwent gamma knife radiosurgery. PATHOLOGICAL FINDINGS The PPT presented with areas of tumor cells forming pineocytomatous rosettes and areas of giant and multinucleated cells with hyperchromatic nuclei. Neither mitosis nor necrosis was observed. The tumor cells were positive for synaptophysin(SYN)and neurofilament(NF), but negative for glial fibrillary acidic protein(GFAP)and oligodendrocyte lineage transcription factor 2 (Olig2). The MIB-1 labeling index(LI)was 8.1%. There was no difference in the MIB-1 LI between pleomorphic and non-pleomorphic areas. All the 12 PPTs were immunopositive for the neuronal markers SYN and NF. The MIB-1 LI was 0% in PC, 3.5% in PPTID, and 10.5% in PB. The proliferative potential was correlated with the WHO grade. From these findings, the final diagnosis of this pleomorphic case was PPTID grade II, not PC, because the MIB-1 LI was relatively high, even though some tumor cells were forming pineocytomatous rosettes. CONCLUSION Although cytologic pleomorphism in PPTs is generally considered not to be correlated with the malignancy grade, the final pathological diagnosis should be determined while considering the proliferative potential.