Nozomi Matsumura

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.

Olig2‐positive cells in glioneuronal tumors show both glial and neuronal characters: The implication of a common progenitor cell?

Glioneuronal tumors (GNTs) are rare neoplasms consisting of both glial and neuronal components. Among the GNTs, dysembryoplastic neuroepithelial tumors (DNTs), papillary glioneuronal tumors (PGNTs), and rosette‐forming glioneuronal tumors of the fourth ventricle (RGNTs) share the character of being mainly composed of small round Olig2‐positive tumor cells. Using immunohistochemistry and fluorescence in situ hybridization, we examined a series of 35 GNT cases (11 DNTs, 15 PGNTs and 9 RGNTs) on the characteristics of Olig2‐positive tumor cells. Histologically, Olig2‐positive cells showed small round forms in most GNTs; however, there were a small number of Olig2‐positive cells with neuronal morphology only in a PGNT case. These cells expressed both glial and neuronal markers by double immunostaining. With regard to labeling indices and intensity, only PGNT cells expressed neuronal markers, including α‐internexin and neurofilament. These findings also suggest that some Olig2‐positive PGNT cells may show neuronal differentiation. In GNTs, a considerable number of Olig2‐positive cells showed immunopositivity for cyclin D1 and/or platelet‐derived growth factor receptor alpha (PDGFRα), which are markers for oligodendrocyte progenitor cells. These immunostainings were particularly strong in DNTs. In RGNTs, Olig2‐positive cells formed “neurocytic rosettes”. Furthermore, they were also immunopositive for glial markers, including GFAP, PDGFRα and cyclin D1. These findings indicate the heterogeneous characteristics of Olig2‐positive cells in GNTs, and some of them also exhibited neuronal features. So it is possible that a part of Olig2‐positive GNT cells have characteristics similar to those of progenitor cells.

Coexpression of glial and neuronal markers in the neurocytic rosettes of rosette-forming glioneuronal tumors

Rosette-forming glioneuronal tumor of the fourth ventricle (RGNT) is a new entity in the WHO 2007 Classification of Tumors of the Central Nervous System. RGNT has two components: neurocytic rosettes and low-grade gliomas. Neurocytic rosettes are conventionally described as consisting of uniform neurocytes. However, some studies have reported rosette-forming tumor cells that expressed glial markers such as Olig2. We indicated the expression of glial markers including Olig2, cyclinD1, glial fibrillary acidic protein (GFAP), and platelet-derived growth factor receptor alpha (PDGFRα) in the neurocytic rosettes in our previous study, and we suggested that these tumor cells had a heterogeneous nature. In this study, we used double and triple immunostaining to demonstrate that these tumor cells have both glial and neuronal characteristics. We found that rosette-forming tumor cells coexpressed Olig2/cyclinD1 and synaptophysin. Furthermore, the cores of the rosettes coexpressed GFAP/PDGFRα in the peripheral zone and synaptophysin in the central zone. These findings imply that rosette-forming tumor cells have a similar nature to neuronal-glial progenitor cells, and we believe that the nomination “neurocytic rosette” may be unsuitable given their heterogeneous nature. Our study appears to clarify some of the properties of RGNT tumor cells and may help elucidate the histogenesis of RGNT.

Hepatocellular Carcinoma Mimicking Liver Abscesses in a Cirrhotic Patient with Severe Septic Shock as a Result of Salmonella O9 HG Infection.

We describe a case of severe Salmonella O9 HG sepsis with a mass in the liver, which was diagnosed as hepatocellular carcinoma (HCC) by autopsy of the liver. The patient was a 67-year-old man with chronic high blood pressure. In addition, he was an alcoholic and had been drinking every day for many years. He had had a dinner of ‘sukiyaki’ with a raw egg two days before admission. The next morning, he had developed vomiting, diarrhea, and abdominal pain. Salmonella O9 HG was found in the blood and stool cultures. In the computed tomography (CT) finding of the liver, there was a 2 cm early-enhanced mass with a multilocular structure, with ringed enhancement and daughter nodes. Since we thought that the mass was a liver abscess, we performed needle aspiration from the liver mass and were able to withdraw blood. Despite adequate antibiotic treatment, the patient died as a result of complications on the 55th day after admission. After the patient’s death, we conducted an autopsy. There were two HCC masses, a moderately-differentiated and a well-differentiated mass, as a result of alcoholic cirrhosis of the liver. As the HCC had multilocular cyst-like structures, which were fiber- and necrosis-rich, CT images of the liver masses resembled abscesses.

Histone H3 K27M mutations in adult cerebellar high-grade gliomas

Adult cerebellar high-grade gliomas (HGG) are rare and their molecular basis has not been fully elucidated. Although a diffuse midline glioma H3 K27M-mutant, a recently characterized variant of HGG, was reported to occasionally occur in the cerebellum, adult cases were rarely tested for this mutation; only five mutant cases have been reported to date. It currently remains unknown whether H3 K27M-mutant cerebellar gliomas share common histological features or have a uniformly dismal prognosis. In the present study, we assessed the prevalence of histone H3 K27M mutations in ten adult cerebellar HGG, identifying two H3F3A-mutant cases. One case was a 70-year-old female with a cystic lesion. Histologically, the tumor was considered to be glioblastoma; however, a part of the tumor exhibiting low proliferative activity appeared to be consistent with long-standing H3 K27M-mutant tumors in the literature. Another case was a 69-year-old male. The tumor showed a distinct circumscribed histology with minimal astrocytic differentiation, suggesting a nosological issue in the diagnosis of diffuse midline glioma. More cerebellar tumors need to be tested for H3 K27M mutations to clarify the clinical and histopathological spectra of this tumor.

SLC44A1-PRKCA fusion in papillary and rosette-forming glioneuronal tumors

We investigated the fused protein of solute carrier family 44 choline transporter member 1 (SLC44A1) and protein kinase C alpha (PRKCA) in three patients with papillary glioneuronal tumors (PGNT). PGNT and rosette-forming glioneuronal tumors (RGNT) are recently identified, unusual glioneuronal tumor variants which were categorized as novel tumor entities in the 2007 World Health Organization classification system. The molecular background of these tumors remains poorly understood due to the paucity of studies. The SLC44A1-PRKCA fusion was recently detected in three cases of PGNT. We invesitgated for the SLC44A1-PRKCA fusion protein in the three PGNT patients and a further two with RGNT using fluorescence in situ hybridization. Two out of the three PGNT patients had a fused signal (paired red-green signal) representing a rearrangement on chromosomes 9 and 17. A normal signal pattern was observed in the third PGNT patient. Neither of the two RGNT patients demonstrated a fused signal. This suggests that the SLC44A1-PRKCA fusion is a characteristic alteration in PGNT but not RGNT. Therefore, it is a potential biomarker of PGNT. The paired red-green signal that was observed in the PGNT patients implies the presence of a different breakpoint than that previously reported in the 9q31 and 17q24 genes.

BRAF V600E, TERT promoter mutations and CDKN2A/B homozygous deletions are frequent in epithelioid glioblastomas: a histological and molecular analysis focusing on intratumoral heterogeneity

Epithelioid glioblastoma (E‐GBM) is a rare aggressive variant of IDH‐wildtype glioblastoma newly recognized in the 2016 World Health Organization classification, composed predominantly of monotonous, patternless sheets of round cells with laterally positioned nuclei and plump eosinophilic cytoplasm. Approximately 50% of E‐GBM harbor BRAF V600E, which is much less frequently found in other types of glioblastomas. Most E‐GBM are recognized as primary/de novo lesions; however, several E‐GBM with co‐ or pre‐existing lower‐grade lesions have been reported. To better understand associations between E‐GBM and the lower‐grade lesions, we undertook a histological and molecular analysis of 14 E‐GBM, 10 of which exhibited lower‐grade glioma‐like components (8 E‐GBM with co‐existing diffuse glioma‐like components, 1 E‐GBM with a co‐existing PXA‐like component and 1 E‐GBM with a pre‐existing PXA). Molecular results demonstrated that the prevalence of BRAF V600E, TERT promoter mutations and CDKN2A/B homozygous deletions in E‐GBM were 13/14 (93%), 10/14 (71%) and 11/14 (79%), respectively, and concurrent BRAF V600E, TERT promoter mutations and CDKN2A/B homozygous deletions were observed in 7/14 (50%) of E‐GBM. These alterations were also frequently seen in the lower‐grade lesions irrespective of the histology. Genetic analysis including array comparative genomic hybridization performed for 5 E‐GBM with co‐ and pre‐existing lower‐grade components revealed that all molecular changes found in the lower‐grade components were also observed in the E‐GBM components, and additional changes were detected in the E‐GBM components. In conclusion, E‐GBM frequently exhibit BRAF V600E, TERT promoter mutations and CDKN2A/B homozygous deletions and these alterations tend to coexist in E‐GBM. Taken together with the facts that only one PXA preceded E‐GBM among these lower‐grade lesions, and that co‐occurrence of BRAF V600E, TERT promoter mutations and CDKN2A/B homozygous deletions have been reported to be rare in conventional lower‐grade diffuse gliomas, the diffuse glioma‐like components may be distinct infiltrative components of E‐GBM, reflecting intratumoral heterogeneity.

Coexpression of cyclin D1 and alpha-internexin in oligodendroglial tumors

Oligodendroglial tumors with neuronal differentiation cases have been reported in recent studies. Oligodendrocyte precursor cells (OPCs) give rise to both oligodendrocytes and neurons; however, little is known about the association between OPCs and oligodendroglial tumors with neuronal differentiation. Previously, we observed the coexpression of cyclin D1, one of the OPC markers, and alpha-internexin (INA) in oligodendroglial tumor cells. INA is a neuronal marker, and has been indicated as an immunohistochemical surrogate of chromosome 1p/19q co-deletion in oligodendroglial tumors. In this study, we investigated the expression status in 83 gliomas immunohistochemically, and found that cyclin D1-positive cells were commonly detected in gliomas. There was no correlation between the cyclin D1 and Ki-67 labeling indices, suggesting an unrecognized role of cyclin D1 other than a cell cycle regulator in gliomas. Cyclin D1/INA double-positive cells were consistently observed in oligodendroglial tumors regardless of histological grade. In 2 cases of oligodendroglioma with neuronal differentiation, the tumor cells of neuronal morphology showed higher expression of INA, suggesting INA expression may be associated with a bona fide neuronal phenotype. The prevalence of cyclin D1/INA double-positive cells is a distinct feature of oligodendroglial tumors. This new characteristic finding may have practical utility in glioma classification.

Immunophenotypic features of immaturity of neural elements in ovarian teratoma

Neural components in mature teratomas are common and the general assumption is that they are quite similar to those in the mature central nervous system (CNS). We investigated 44 ovarian teratomas by immunohistochemistry to determine cellular and structural immaturity of neural elements. Most teratomas contained cells differentiating into astrocytes positive for nestin, a neural stem cell marker. These nestin-positive astrocytes generally co-expressed glial fibrillary acidic protein-delta, an immature astrocyte marker. Olig2-positive cells were randomly scattered. Areas comprising cells that differentiated into neurons were positive for NeuN and synaptophysin. The border between white and gray matter was ill-defined and more NeuN-positive cells were distributed in areas that were positive for myelin basic protein, indicating that the distribution of neurons and glial cells was disturbed. Peripheral nerve bundles positive for Schwann/2E, an antigen specific for myelinating Schwann cells, were mixed within CNS-like tissues. These results show that apparently mature teratomas are not in fact mature, at least in terms of neural elements, as they harbor immature cells and structural abnormalities. The neural elements of surgically resected teratomas might represent a premature state of the human CNS, and thus be potentially useful for studies of developmental neurobiology as well as gliomagenesis.

Hydroxyurea-induced Pneumonitis in a Patient with Chronic Myelomonocytic Leukemia: An Autopsy Case.

We describe the case of an 85-year-old man diagnosed with chronic myelomonocytic leukemia whose disease was treated with hydroxyurea for 3 months. He developed respiratory symptoms that were extensively investigated. Despite the intensive treatment, he died of respiratory failure eleven days later. An autopsy revealed diffuse interstitial inflammation of both lungs consistent with drug-induced inflammation. A drug lymphocyte stimulation test was positive for hydroxyurea. Taken together these findings demonstrated that severe interstitial pneumonitis was induced by this drug. Physicians using hydroxyurea must be aware of its potentially life-threatening pulmonary toxicity.