Hayato Ikota

Systematic immunohistochemical profiling of 378 brain tumors with 37 antibodies using tissue microarray technology

We performed a systematic immunohistochemical study on 378 brain tumors using 37 antibodies and tissue microarray (TMA) technology. The aim of this study was to find new diagnostic biomarkers using antibodies established in our laboratory. Our TMA consisted of a grid of 1.5-mm cores that were extracted from individual donor blocks. Staining for each antibody was scored using a three-point system. We used hierarchical clustering analysis to interpret these data, which resulted in separation of all the brain tumors into seven groups. Although there were some exceptions, cases with the same histological diagnosis were generally grouped together. We then carried out statistical analyses to find the most useful antibodies for grouping of brain tumors. Ten antibodies [glial fibrillary acidic protein (GFAP), Olig2, vimentin, epithelial membrane antigen (EMA), cytokeratin (AE1/AE3), alpha-internexin, nestin, pinealocytes PP5, aquaporin-4 (AQP4) M13d and AQP4M13e] discriminated between astrocytomas and oligodendroglial tumors. Six antibodies [EMA, AE1/AE3, TUJ1, nestin, neurofilament protein-MH (NF-MH) and perivascular cells GP-1] showed significant differences between high-grade and low-grade gliomas. Our data have revealed new antibodies with potential diagnostic utility (Olig2, PP5, GP-1) and demonstrate that TMA technology is highly useful for evaluating newly established antibodies in brain-tumor research.

Frequent IDH1 / 2 mutations in intracranial chondrosarcoma: a possible diagnostic clue for its differentiation from chordoma

Mutations in the genes encoding isocitrate dehydrogenase (IDH) 1/2 have been detected in a significant proportion of diffuse gliomas and in a small fraction of acute myeloid leukemia (AML) cases. Recently, in an examination of various types of mesenchymal tumor, IDH1/2 mutations were only found in cartilaginous tumors including central conventional and periosteal enchondromas/chondrosarcomas. The frequency of IDH1/2 mutations was 56%, and the IDH1 R132C mutation, which is not common in diffuse gliomas or AML, accounted for 40% of these mutations. In this study, we investigated the IDH1/2 mutation status of intracranial chondrosarcomas and chordomas, which are morphologically similar and affect similar regions of the cranial cavity. Of the 13 chondrosarcomas analyzed, six (46.1%) displayed IDH1/2 mutations (the predominant type was IDH1 R132C). Also, an IDH2 mutation (R172S) was observed in one case. Conversely, none of the ten chordomas analyzed displayed any IDH1 or IDH2 mutations. Our data suggest that the IDH1/2 mutation status could be valuable for distinguishing intracranial chondrosarcomas from chordomas.

Nestin expression in brain tumors: its utility for pathological diagnosis and correlation with the prognosis of high-grade gliomas.

One of the type VI intermediate filament proteins, nestin, is expressed in neuroepithelial stem cells during neural embryogenesis. Nestin is also expressed in a variety of neoplasms. Its expression in brain tumors has not been thoroughly studied. The objectives of this study were to survey nestin expression in different types of brain tumor, and to evaluate nestin as a marker for diagnosis and prognosis. We used tissue microarrays of 257 brain tumors for an immunohistochemical overview of nestin expression: nestin was frequently expressed in gliomas and schwannomas. Most of the gliomas that expressed high levels of nestin were high-grade gliomas (anaplastic astrocytomas, anaplastic oligodendrogliomas, anaplastic oligoastrocytomas, and glioblastomas). We then focused on high-grade gliomas and performed immunohistochemistry again, using whole-mount slides. As a result, we found (1) significantly different nestin expression between glioblastomas and other high-grade gliomas, and (2) worse overall survival for high-grade gliomas with high nestin expression. Our results suggest that: (1) nestin is a useful marker for diagnosis of high-grade gliomas, (2) nestin is helpful in diagnosis of schwannomas, and (3) nestin expression is related to poor prognosis in high-grade gliomas.

Intratumoral Heterogeneity of Genomic Imbalance in a Case of Epithelioid Glioblastoma with BRAF V600E Mutation

Epithelioid glioblastoma is among the rarest variants of glioblastoma and is not formally recognized in the World Health Organization classification; it is composed of monotonous, discohesive sheets of small, round cells with eccentric nuclei and eosinophilic cytoplasm devoid of cytoplasmic stellate processes, showing the retention of nuclear staining of INI‐1 protein. Here, we report a case involving a 22‐year‐old man with a right occipital lobe tumor, which comprised mainly epithelioid tumor cells with a small area of diffusely infiltrating less atypical astrocytoma cells showing a lower cell density. Array comparative genomic hybridization separately performed for each histologically distinct component demonstrated eight shared copy number alterations (CNAs) and three CNAs observed only in epithelioid cells; one of the latter was a homozygous deletion of a tumor suppressor gene, LSAMP, at 3q13.31. BRAF V600E mutation was observed both in epithelioid tumor cells and in diffusely infiltrating less atypical astrocytoma cells. Our findings suggest that the regional loss of LSAMP led to the aggressive nature of epithelioid cells in the present case of epithelioid glioblastoma.

Concurrent TERT promoter and BRAF V600E mutation in epithelioid glioblastoma and concomitant low-grade astrocytoma.

Epithelioid glioblastoma (E‐GBM) is a rare variant of glioblastoma (GBM), characterized by epithelioid cells with eosinophilic round cytoplasm devoid of stellate cytoplasmic processes. A number of studies have demonstrated that more than half of E‐GBMs harbor a valine to glutamic acid substitution at position 600 of the serine/threonine‐protein kinase BRAF (BRAF V600E). However, there are no previous reports on E‐GBM with telomerase reverse transcriptase (TERT) promoter mutation in addition to BRAF V600E mutation. Here, we report an E‐GBM case in an 18‐year‐old man with BRAF V600E and TERT promoter mutations. The tumor composed of 80% E‐GBM and 20% diffuse astrocytoma‐like components, and BRAF V600E and TERT promoter mutations were detected in both. E‐GBM generally arises as a primary lesion; however, a few previous cases have been demonstrated to accompany low‐grade areas. Demonstration of concurrent BRAF V600E and TERT promoter mutations in low‐ and high‐grade lesions strongly suggested their identical origin, and acquisition of each mutation may be an early event, possibly playing a pivotal role in the genesis and subsequent progression to E‐GBM.

High-throughput immunohistochemical profiling of primary brain tumors and non-neoplastic systemic organs with a specific antibody against the mutant isocitrate dehydrogenase 1 R132H protein

Isocitrate dehydrogenase 1 (IDH1) mutations are common in grade II–III diffuse gliomas and secondary glioblastomas. The aim of this study is to investigate the staining pattern of mIDH1R132H, an antibody specific to mutant IDH1 protein, in primary brain tumors and non-neoplastic systemic organs. Eight of 13 diffuse astrocytomas, 1 of 6 anaplastic astrocytomas, 9 of 11 oligodendrogliomas, 15 of 22 anaplastic oligodendrogliomas, 6 of 7 oligoastrocytomas, and 5 of 8 anaplastic oligoastrocytomas showed both cytoplasmic and nuclear positivity. Two of 25 atypical meningiomas and 2 of 42 pituitary adenomas were positive for mIDH1R132H. The following non-neoplastic systemic organs showed positivity in the cytoplasm alone: the myocardium, peribronchial glands, interlobular ducts of the salivary gland, gastric fundic gland, columnar epithelia of the large bowel, hepatocytes, centroacinar cells, the intercalated ducts of the pancreas, renal proximal and distal tubules, adrenocortex, ovarian granulosa cells, and the choroid plexus epithelia. It was concluded that the immunopositivity detected in non-neoplastic systemic organs was due to cross-reactivity, because immunohistochemistry with an anti-mitochondrial antibody revealed that the mIDH1R132H staining pattern was identical to that of the mitochondria. Therefore, mIDH1R132H positivity should only be considered to be validated when a cell shows both cytoplasmic and nuclear staining.

Malignant transformation of ovarian mature cystic teratoma with a predominant pulmonary type small cell carcinoma component

A 68‐year‐old woman was diagnosed with mature cystic teratoma of the left ovary when she was 44 years old. The tumor recently enlarged rapidly, and abdominal magnetic resonance imaging revealed an intrapelvic cystic lesion, which measured 123 × 120 × 107 mm and contained a mural nodule. Under a clinical diagnosis of malignant transformation of mature cystic teratoma, bilateral salpingo‐oophorectomy with total hysterectomy and omentectomy were performed. The resected specimen showed a unilocular cystic lesion containing a well‐demarcated mural nodule measuring 35 × 30 × 25 mm in the left ovary. A microscopic examination revealed various types of carcinoma in the mural nodule: pulmonary type small cell carcinoma (65%), adenocarcinoma (25%), squamous cell carcinoma (5%), and transitional cell carcinoma (5%). Small cell carcinoma was positive for CD56, synaptophysin, and chromogranin A. The adenocarcinoma component showed intestinal phenotypes; i.e. cytokeratin (CK) 7(−), CK20(+), CDX2(+), estrogen receptor(−), and progesterone receptor (−). Interestingly, CDX2 positivity was retained in all of the carcinomas. It was assumed that the adenocarcinoma had arisen from an intestinal epithelium in the mature cystic teratoma and then differentiated into the diverse histological types mentioned above.

Atypical Teratoid/Rhabdoid Tumor (AT/RT) Arising From Ependymoma: A Type of AT/RT Secondarily Developing From Other Primary Central Nervous System Tumors.

Atypical teratoid/rhabdoid tumors (AT/RT) are rare, aggressive, embryonal brain tumors that occur most frequently in very young children; they are characterized by rhabdoid cells and loss of INI1 protein nuclear expression. Here, we report the case of a 24-year-old man with a left frontal lobe tumor that was composed mainly of rhabdoid cells showing loss of INI1 nuclear reactivity and polyphenotypic immunohistochemical expression, with a small INI1-positive component of ependymoma. Array comparative genomic hybridization separately conducted for each histologically distinct component revealed 22 shared identical copy number alterations, including loss of heterozygosity of chromosome 22q containing the INI1 locus. Furthermore, we found the C11orf95-RELA fusion gene, the genetic hallmark of supratentorial ependymomas, not only in the ependymoma component but also in the AT/RT component by fluorescence in situ hybridization analysis, suggesting that the AT/RT cells secondarily progressed from the preexisting ependymoma cells. A second genetic inactivating event in the INI1 gene was not detected in the AT/RT component. There are several reported cases of AT/RT (or INI1-negative rhabdoid tumors) arising in the setting of other primary brain tumors (gangliogliomas, pleomorphic xanthoastrocytomas, and high-grade gliomas), but the present case is the first reported AT/RT apparently evolving from an ependymoma.

Slug, Twist, and E-Cadherin as Immunohistochemical Biomarkers in Meningeal Tumors

The overexpression of Twist and Slug and subsequent down-regulation of E-cadherin facilitate the acquirement of invasive growth properties in cancer cells. It is unclear which of these molecules are expressed in mesenchymal tumors in the central nervous system. Here, we investigated 10 cases each of hemangiopericytoma, solitary fibrous tumor, meningothelial, fibrous, angiomatous, and atypical meningiomas, and 5 cases of anaplastic meningioma for Slug, Twist, E-cadherin, and N-cadherin immunoexpression. Nuclear Slug expression was observed in 9/10 (90%) hemangiopericytomas and 5/10 (50%) solitary fibrous tumors, but not in any meningiomas, except for 1 case. Similarly, nuclear Twist expression was more extensive in hemangiopericytomas and solitary fibrous tumors than meningiomas. In contrast to Slug and Twist, the positive expression of E-cadherin was observed in 39/45 (87%) meningiomas, but not in any hemangiopericytomas or solitary fibrous tumors (P<0.0001). The fraction of tumor cells expressing E-cadherin in meningeal tumors was negatively correlated to those of Twist (P = 0.004) and Slug (P<0.0001). The overexpression of Slug and Twist with down-regulation of E-cadherin was characteristic findings in hemangiopericytomas and solitary fibrous tumors, but not in meningiomas. The immunohistochemical profiles of the two tumor groups may be useful as diagnostic markers in cases that present a differential diagnosis challenge.

Ureteral leiomyoma causing hydronephrosis in Type 1 multiple endocrine neoplasia.

A rare case of leiomyoma of the ureter in a patient with type 1 multiple endocrine neoplasia (MEN) is reported. The case is of a Japanese man in his forties who had a past history of parathyroid gland hyperplasia, pancreatic islet cell tumors, and bilateral adrenocortical nodular hyperplasia. The leiomyoma, measuring 15 × 13 × 12 mm, was located in the right upper ureter, obstructing the lumen and causing hydronephrosis. Three small leiomyomas were also detected in the lower portion. Furthermore, histological examination revealed three tiny leiomyomatous nodules embedded in the muscular layer. It has been reported that type 1 MEN is often complicated by multiple leiomyoma in many organs, including the esophagus, stomach, lung, uterus, and skin. However, it is believed that this is the first report of leiomyomatosis of the ureter occurring in a patient with type 1 MEN. It should be recognized that multiple ureteral leiomyomas may develop in patients of type 1 MEN and can potentially result in hydronephrosis. The multiple development of leiomyoma suggests a causal relationship to MEN1 gene alteration.