Chih-Yi Hsu

Atypical teratoid/rhabdoid tumor of the central nervous system: a comparative study with primitive neuroectodermal tumor/medulloblastoma

Abstract Eleven atypical teratoid/rhabdoid tumors (AT/¶RT) and 121 primitive neuroectodermal tumors/medulloblastomas (PNET/MB) were included in this study for evaluation of the histopathological features of AT/RT and comparison between AT/RT and PNET/MB. Histopathological studies of AT/RT showed that in addition to the commonly recognized components, i.e., rhabdoid cells, small (PNET/MB) cells, spindle cells and epithelial components, there was a previously unrecognized component, sickle-shaped embracing cells, which were present in all cases and could be useful as a histological marker of this tumor. Immunohistochemical studies showed divergent differentiation of the tumor cells and among the 16 antibodies studied, vimentin, neuron-specific enolase, epithelial membrane antigen and glial fibrillary acidic protein were most commonly reactive. The frequency of AT/RT expressed as a ratio of AT/RT to PNET/MB was 1u2002:u200211 in general and increased to 1u2002:u20023.8 among patients younger than 3 years old. The AT/RT patients were younger than those with PNET/MB and had a female predominance. The MIB-1 labeling index of AT/RT was significantly higher than that of PNET/MB (mean 63.9 vs 40.1), which correlated with a shorter survival in patients with AT/¶RT than those with PNET/MB (median survival time ¶15.4 months vs 156.4 months).n

A clinicopathologic study of 81 patients with ependymomas and proposal of diagnostic criteria for anaplastic ependymoma.

Optimal histologic criteria for the classification of and grading of ependymomas, including their anaplastic forms, remain elusive. This is especially true because of the poor correlation of these criteria with clinical outcome. The aim of this study was to identify the histopathologic parameters that could distinguish different prognostic groups of patients with ependymomas. Eighty-one patients with ependymal tumors, including those originally diagnosed ependymomas, anaplastic ependymomas and myxopapillary ependymomas, were enrolled in this study. Thirteen histologic parameters, including hypercellularity, nuclear pleomorphism, mitoses, endothelial proliferation, necrosis, clear cell, thrombi, dystrophic calcification, psammoma bodies, bone, cartilage, Rosenthal fibers and MIB-1 labeling index (LI), were evaluated in each patient and correlated with clinical outcome. We assigned one score for each histopathologic parameter evaluated and used a stepwise selection method with entry model based on the significance of the log-rank statistic to formulate a scoring model. Four parameters were chosen in this process, including mitoses ≥u20094/10u2009hpf (1.7/mm2), hypercellularity, endothelial proliferation and necrosis. The sum of these four parameters (scores) was the histopathologic score of the tumor. The progression-free survival (PFS) and overall survival (OS) of patients with histopathologic scores 0 and 1 were significantly better than those with histopathologic scores 2, 3 and 4 (p < 0.001 and p = 0.005, respectively). Because of the latter finding, we proposed that anaplastic ependymoma could be diagnosed by the presence of any two of the aforementioned four parameters. Multivariate analyses including clinical and histopathologic variables showed that histopathologic score ≥ 2 and subtotal resection were the factors related to increased risk of recurrence, while histopathologic score ≥ 2 was the only factor related to overall survival. Based on the above findings, we concluded that histopathology is an important prognostic indicator for patients with ependymomas.

A 35-year retrospective study of carcinoid tumors in Taiwan: differences in distribution with a high probability of associated second primary malignancies.

A comprehensive study of carcinoid tumors from United States‐based databases indicated that the small intestine, colon, rectum, and bronchopulmonary system are common locations for carcinoid tumors. In addition, certain carcinoid tumors, such as rectal carcinoids, appeared to be overrepresented in nonwhite populations in the United States. High frequencies of associated noncarcinoid malignancies were reported in some articles. The objective of the current study was to address the organ distribution, frequency of metastasis, and survival rates of carcinoid tumors and the associated noncarcinoid tumors in Taiwanese, Asian populations.

Small cell carcinomas in gastrointestinal tract: immunohistochemical and clinicopathological features

Aims To test the incidence of the expression of the immunohistochemical markers that aid diagnosis of gastrointestinal tract small cell carcinoma (GI-SmCC) and to evaluate the incidence of mixed endocrine–exocrine carcinomas in GI-SmCC. Methods Immunohistochemical studies of three antibodies against epithelial markers (CK8, AE1/AE3, EMA), four neuroendocrine differentiation markers (synaptophysin (Syn), neuron specific enolase (NSE), neuronal cell adhesion molecules (CD56), chromogranin A (CgA)), and a transcription factor (thyroid transcription factor 1 (TTF-1)) were performed. The incidence of non-endocrine carcinoma component was evaluated in 42 GI-SmCCs (11 in the oesophagus, 15 in the stomach, 15 in the colon, and 1 in the small intestine). Results The percentages of GI-SmCC with positive immunoreactivity were: CK8 92.9%, AE1/AE3 76.2%, EMA 71.4%, Syn 100%, NSE 100%, CD56 90.5%, CgA 61.9%, TTF-1 21.4%. The low molecular weight cytokeratin CK8 is more commonly expressed in GI-SmCC than is the expression of AE1/AE3 or EMA. Synaptophysin and NSE are expressed in all GI-SmCCs studied. Non-endocrine carcinoma components were demonstrated in 8 patients (4 in the oesophagus and 4 in the stomach). Conclusion In detecting GI-SmCC, epithelial marker CK8 is more sensitive than AE1/AE3 or EMA, and neuroendocrine differentiation markers synaptophysin and NSE are the most useful markers. TTF-1 positivity is not uncommon in GI-SmCC, but cases with negative TTF-1 staining may indicate an extra-pulmonary primary. Non-endocrine carcinoma components were demonstrated in about 30% of oesophagus and stomach SmCC; the neoplasms should be diagnosed as mixed endocrine–exocrine carcinoma.

Exclusion of histiocytes/endothelial cells and using endothelial cells as internal reference are crucial for interpretation of MGMT immunohistochemistry in glioblastoma.

We evaluated the predictive value of O6-methylguanine-DNA methyltransferase (MGMT) protein expression and MGMT promoter methylation status in glioblastomas (GBM) treated with temozolomide (TMZ) in a Taiwan medical center. Protein expression by immunohistochemical analysis (IHC) and MGMT promoter methylation detected by methylation-specific polymerase chain reaction (MSP) were performed in a series of 107 newly diagnosed GBMs. We used endothelial cells as an internal reference for IHC staining because the staining intensities of the MGMT-expressing cells in different specimens varied considerably; a positive result was defined as the staining intensity of the majority of tumor cells similar to that of the adjacent endothelial cells. Immunostainings for microglial/endothelial markers were included as part of the MGMT IHC evaluation, and in cases that were difficult to interpret, double-labeling helped to clarify the nature of reactive cells. The MGMT protein expression was reversely associated with MGMT promoter methylation status in 83.7% of cases (MSP+/IHC− and MSP−/IHC+; Pearson r=−0.644, P<0.001). Twenty-two of 24 (91.7%) IHC+ tumors did not respond to TMZ treatment. Combining MSP and IHC results, all the 15 MSP−/IHC+ GBMs were TMZ resistant. The MGMT status detected by either IHC or MSP was significantly correlated with the TMZ treatment response (both P<0.001) and survival of GBM patients (both P<0.05).

A 20-year retrospective study of small-cell carcinomas in Taiwan

Small‐cell carcinomas (SCC) develop most commonly in the lung (small‐cell lung carcinoma, SCLC) and only small percentages are present at extra‐pulmonary sites. This study aimed to examine the distribution, treatment, and survival of SCCs.

Prognosis of glioblastoma with faint MGMT methylation-specific PCR product.

Methylation-specific polymerase chain reaction (MSP) for the promoter methylation status of O6-methylguanine-DNA-methyltranferase (MGMT) gene theoretically provides a positive or negative result. However, the faint MSP product is difficult to interpret. The aim of this study was to evaluate the significance of faint MSP product in glioblastoma (GBM). Critical concentrations of methylated control DNA, i.e., 100, 1, 0.5 and 0xa0% were run parallel with 116 newly diagnosed GBMs in order to standardize the interpretation and to distinguish positive (+), equivocal (±), and negative (−; unmethylated) results. Cases with the faint MSP product and its intensity between those of 1 and 0.5xa0% DNA controls were considered equivocal (±). MGMT methylation quantifications were also determined by quantitative real-time MSP (qMSP) and pyrosequencing (PSQ), and protein expression was detected by immunohistochemistry. There were significant correlations between MSP and all the aforementioned studies. The concordance rates between the MSP+ and qMSP+ cases, as well as the MSP− and qMSP− cases were 100xa0%, and the MSP± cases comprised 76.5xa0% of qMSP+ cases and 23.5xa0% of qMSP− cases. PSQ study showed that heterogeneous methylation was more frequently encountered in the MSP± cases. Multivariate analyses disclosed that although the overall survival of the MSP± cases was indistinct from that of the MSP+ cases, its progression free survival was significantly worse and was indistinct from that of the MSP− cases. In conclusion, GBMs with faint MGMT MSP products should be distinguished from MSP+ cases as their behaviors were different.

Extra-departmental anatomic pathology expert consultation inTaiwan: a research grant supported 4-year experience.

This report analyzed a research project supported nationwide expert consultation of anatomic pathology in Taiwan.

Thyroid transcription factor-1 distinguishes subependymal giant cell astrocytoma from its mimics and supports its cell origin from the progenitor cells in the medial ganglionic eminence

Subependymal giant cell astrocytoma is a benign brain tumor mostly associated with tuberous sclerosis complex. However, it may be misinterpreted as other high-grade brain tumors due to the presence of large tumor cells with conspicuous pleomorphism and occasional atypical features, such as tumor necrosis and endothelial proliferation. In this study, we first investigated thyroid transcription factor-1 (TTF-1) expression in a large series of subependymal giant cell astrocytomas and other histologic and locational mimics to validate the diagnostic utility of this marker. We then examined TTF-1 expression in non-neoplastic brain tissue to determine the cell origin of subependymal giant cell astrocytoma. Twenty-four subependymal giant cell astrocytoma specimens were subjected to tissue microarray construction. For comparison, a selection of tumors, including histologic mimics (21 gemistocytic astrocytomas and 24 gangliogliomas), tumors predominantly occurring at the ventricular system (50 ependymomas, 19 neurocytomas, and 7 subependymomas), and 134 astrocytomas (3 pleomorphic xanthoastrocytomas, 45 diffuse astrocytomas, 46 anaplastic astrocytomas, and 40 glioblastomas) were used. Immunohistochemical stain for TTF-1 was positive in all 24 subependymal giant cell astrocytomas, whereas negative in all astrocytomas, gangliogliomas, ependymomas, and subependymomas. Neurocytomas were positive for TTF-1 in 4/19 (21%) of cases using clone 8G7G3/1 and in 9/19 (47%) of cases using clone SPT24. In the three fetal brains that we examined, TTF-1 expression was seen in the medial ganglionic eminence, a transient fetal structure between the caudate nucleus and the thalami. There was no BRAFV600E mutation identified by direct sequencing in the 20 subependymal giant cell astrocytomas that we studied. In conclusion, TTF-1 is a useful marker in distinguishing subependymal giant cell astrocytoma from its mimics. Expression of TTF-1 in the fetal medial ganglionic eminence indicates that subependymal giant cell astrocytoma may originate from the progenitor cells in this region.

MGMT promoter methylation in non-neoplastic brain.

O6–methylguanine–DNA–methyltransferase (MGMT) is mainly regulated by cytosine–guanine island promoter methylation that is believed to occur only in neoplastic tissue. The present study was undertaken to investigate whether methylation occurs also in non-neoplastic brains by collecting 45 non-neoplastic brains from autopsies and 56 lobectomy specimens from epileptic surgeries. The promoter methylation status of MGMT was studied by methylation-specific polymerase chain reaction (MSP) and pyrosequencing (PSQ), while protein expression was studied by immunohistochemical stain (IHC). The methylation rates, as determined by MSP and PSQ, were 3.0xa0% (3/101) and 2.9xa0% (2/69), respectively. Of note, no case had positive result concomitantly from both MSP and PSQ (3 were MSP+/PSQ− and 2 were MSP−/PSQ+), and all the positive samples were further confirmed by cloning and Sanger sequencing. All the methylated cases, except for those having indeterminate IHC results from autopsy specimens, revealed no loss of MGMT protein expression and similar staining pattern to that of the unmethylated cases. In conclusion, the current study demonstrated that MGMT promoter methylation could occur in a low percentage of non-neoplastic brains but did not affect the status of protein expression, which could be regarded as a normal variation in non-neoplastic brains.