Vishwa Jeet Amatya

Immunohistochemical marker panels for distinguishing between epithelioid mesothelioma and lung adenocarcinoma

The distinction between epithelioid mesothelioma and lung adenocarcinoma remains an important diagnostic challenge for surgical pathologists. The aim of the present study was to select a limited and appropriate panel of antibodies that can differentiate between epithelioid mesothelioma and lung adenocarcinoma. Specimens of 90 epithelioid mesotheliomas and 51 lung adenocarcinomas obtained from Japanese cases were examined using calretinin, WT1, AE1/AE3, CAM5.2, cytokeratin (CK) 5/6, vimentin, epithelial membrane antigen (EMA), thrombomodulin, CEA, CA19‐9, and CA125. Ninety‐six percent of epithelioid mesotheliomas were positive for calretinin; 99% for WT1; 100% for AE1/AE; 97% for CAM5.2; 70% for CK 5/6; 91% for vimentin; 96% for EMA; 71% for thrombomodulin; 77% for mesothelin; 7% for CEA; 17% for CA19‐9; and 85% for CA125. In contrast, 33% of lung adenocarcinomas were positive for calretinin; 16% for WT1; 100% for AE1/AE3, CAM5.2, and EMA; 41% for CK 5/6; 47% for vimentin; 20% for thrombomodulin; 69% for mesothelin; 98% for CEA; 73% for CA19‐9; and 80% for CA125. For distinguishing between epithelioid mesothelioma and lung adenocarcinoma, the combination of CEA, calretinin and each WT1 or thrombomodulin was suggested to be the best panel of immunohistochemical markers.

Lymphomas and glioblastomas: Differences in the apparent diffusion coefficient evaluated with high b-value diffusion-weighted magnetic resonance imaging at 3 T

BACKGROUND AND PURPOSE As the usefulness of the apparent diffusion coefficient (ADC) obtained from diffusion-weighted images (DWI) for the differential diagnosis between glioblastoma and primary central nervous system lymphoma is controversial, we assessed whether high b-value DWI at b 4000 s/mm(2) could discriminate between glioblastoma and lymphoma. We also compared the power of high- and standard b-value (b-4000, b-1000) imaging on a 3-Tesla (3T) magnetic resonance (MR) instrument. MATERIALS AND METHODS This study was approved by our Institutional Review Board. We acquired DWI at 3T with b = 1000 and b = 4000 s/mm(2) in 10 patients with lymphoma and 14 patients with glioblastoma. The ADC was measured by placing multiple regions of interest (ROI) on ADC maps of the site of enhanced lesions on contrast-enhanced T1-weighted MR images. We avoided hemorrhagic and cystic lesions by using T1-, T2-, FLAIR-, and T2* MR images. The ADC values of each tumor were determined preoperatively from several ROI and expressed as the minimum-, mean-, and maximum ADC value (ADC(MIN), ADC(MEAN), ADC(MAX)). We evaluated the relationship between ADCs and histological information including tumor cellularity. RESULTS All ADC values were statistically associated with tumor cellularity. ADC(MIN) at b-4000 was associated with tumor cellularity more significantly than ADC(MIN) at b-1000. All ADC values were lower for lymphoma than glioblastoma and the statistical difference was larger at b = 4000- than b = 1000 s/mm(2). According to the results of discriminant analysis, the log likelihood was greatest for ADC(MIN) at b = 4000. At a cut-off value of ADC(MIN) = 0.500 × 10(-3)mm(2)/s at b-4000 it was possible to differentiate between lymphoma and glioblastoma (sensitivity 90.9%, specificity 91.7%). CONCLUSIONS Calculating the ADC value is useful for distinguishing lymphoma from glioblastoma. The lowest degree of overlapping and a better inverse correspondence with tumor cellularity were obtained with ADC(MIN) at b-4000 s/mm(2) at 3T MRI.

Methylation of p14 ARF gene in meningiomas and its correlation to the p53 expression and mutation

We have previously reported the statistically significant correlation of immunohistochemical expression of MIB-1 and p53 proteins among benign, atypical, and anaplastic meningiomas and p53 protein expression was high in atypical and anaplastic meningiomas. In the present study, we analyzed 22 cases of meningiomas for mutation of p53 gene in its spectrum of exon 5 to 8 using automated genetic analyzer. We did not find any mutation of p53 in any of these cases, thus suggesting the p53 protein expression is wild type. We analyzed 72 cases of meningiomas for determining the methylation status of p14ARF gene and the immunohistochemical expression of MDM2 protein to explain p53 protein expression in these meningiomas. We found methylation of p14ARF gene in five of 58 cases of benign meningiomas (8.6%), two of 10 cases of atypical meningiomas (20%), and two of four cases of anaplastic meningiomas (50%). In absence of p53 gene mutation, the high percentage of p14ARF gene methylation in high-grade meningioma may have been responsible for accumulation of wild-type p53 protein. In addition, we also found the loss of MDM2 protein in high-grade meningiomas. These deregulations of p14–MDM2–p53 pathway may contribute to the malignant progression of meningioma.

Differential diagnosis of sarcomatoid mesothelioma from true sarcoma and sarcomatoid carcinoma using immunohistochemistry

Differentiation of sarcomatoid mesothelioma from other sarcomatoid tumors involving the pleura and other structures by light microscopy remains an important diagnostic challenge for surgical pathologists. The purpose of the present study was to investigate the utility of diagnostic immunohistochemistry for differentiating sarcomatoid mesothelioma from its histological mimics: true sarcoma and pulmonary sarcomatoid carcinoma. A total of 39 specimens of mesotheliomas with sarcomatoid components, 43 specimens of true sarcomas, and nine specimens of pulmonary sarcomatoid carcinomas were obtained from Japanese patients and examined using a 10‐antibody panel (calretinin, WT1, AE1/AE3, CAM5.2, epithelial membrane antigen, desmin, α‐smooth muscle actin, S‐100 protein, CD34, and CD68). CAM5.2 had the highest sensitivity and specificity for differentiating sarcomatoid mesothelioma from true sarcoma. The combination of CAM5.2, WT1, and AE1/AE3 is recommended for routine pathological diagnosis. Accurate clinical information is necessary for differentiating sarcomatoid mesothelioma from sarcomatoid carcinoma.

Value of immunohistochemistry in the differential diagnosis of pleural sarcomatoid mesothelioma from lung sarcomatoid carcinoma

Aims:  The differential diagnosis of pleural sarcomatoid mesothelioma (SM) from lung sarcomatoid carcinoma (LSC) invading parietal pleura and chest wall is a challenging issue. The aim of this study was to identify useful antibodies that can be used for the differential diagnosis of pleural SM from LSC.

Reg IV is an independent prognostic factor for relapse in patients with clinically localized prostate cancer

Regenerating islet‐derived family, member 4 (REG4, which encodes Reg IV) is a candidate marker for cancer and inflammatory bowel disease. We investigated the potential prognostic role of Reg IV immunostaining in clinically localized prostate cancer (PCa) after radical prostatectomy. Immunohistochemical staining of Reg IV was performed in 98 clinically localized PCa tumors obtained during curative radical prostatectomy. Intestinal and neuroendocrine differentiation was investigated by MUC2 and chromogranin A immunostaining, respectively. The prognostic significance of immunohistochemical staining for these factors on prostate‐specific antigen (PSA)‐associated recurrence was assessed by Kaplan–Meier analysis and a Cox regression model. Phosphorylation of the epidermal growth factor receptor (EGFR) by Reg IV was analyzed by Western blot. In total, 14 (14%) of the 98 PCa cases were positive for Reg IV staining. Reg IV positivity was observed frequently in association with MUC2 (P = 0.0182) and chromogranin A positivity (P = 0.0012). Univariate analysis revealed that Reg IV staining (P = 0.0004), chromogranin A staining (P = 0.0494), Gleason score (P < 0.0001) and preoperative PSA concentration (P = 0.0167) were significant prognostic factors for relapse‐free survival. Multivariate analysis indicated that Reg IV staining (P = 0.0312), Gleason score (P = 0.0014) and preoperative PSA concentration (P = 0.0357) were independent predictors of relapse‐free survival. In the LNCaP cell line, EGFR phosphorylation was induced by the addition of Reg IV‐conditioned medium. These results suggest that Reg IV expression is an independent prognostic indicator of relapse after radical prostatectomy. (Cancer Sci 2008; 99: 1570–1577)

CD26 Overexpression Is Associated with Prolonged Survival and Enhanced Chemosensitivity in Malignant Pleural Mesothelioma

Purpose: Malignant pleural mesothelioma (MPM) is an aggressive and therapy-resistant neoplasm arising from the pleural mesothelial cells, without established indicators to predict responsiveness to chemotherapy. Experimental Design: Our study involving 79 MPM patients showed that 73.4% of MPM expressed CD26 on cell membrane. Results: The majority of epithelioid and biphasic types of MPM expressed CD26 on the cell membrane, whereas the sarcomatoid type showed a lack of CD26 surface expression. Although the sarcomatoid type was associated with poor prognosis (P < 0.0001), no significant relationship between CD26 expression and survival was observed. On the contrary, there was a trend for an association between response rate to chemotherapy and CD26 expression (P = 0.053), with a higher level of CD26 expression more likely to be linked to better response to chemotherapy. Moreover, CD26 expression was a significant factor associated with improved survival in patients who received chemotherapy [median survival time (MST), 18.6 vs. 10.7 months, P = 0.0083]. Furthermore, CD26 expression was significantly associated with better prognosis in patients receiving non–pemetrexed-containing regimens (MST, 14.2 vs. 7.4 months, P = 0.0042), whereas there was no significant association between CD26 expression and survival time for patients receiving pemetrexed-containing regimens. Our in vitro and microarray studies showed that mesothelioma cells expressing high CD26 displayed high proliferative activity, and CD26 expression was closely linked to cell-cycle regulation, apoptosis, and chemotherapy resistance. Conclusions: Our results strongly suggest that CD26 is a clinically significant biomarker for predicting response to chemotherapy for MPM. Clin Cancer Res; 18(5); 1447–56. ©2012 AACR.

Glioblastoma treated with postoperative radio-chemotherapy : Prognostic value of apparent diffusion coefficient at MR imaging

PURPOSE To retrospectively evaluate whether the mean, minimum, and maximum apparent diffusion coefficient (ADC) of glioblastomas obtained from pretreatment MR images is of prognostic value in patients with glioblastoma. MATERIALS AND METHODS The institutional review board approved our study and waived the requirement for informed patient consent. Between February 1998 and January 2006, 33 patients (24 males, 9 females; age range 10-76 years) with supratentorial glioblastoma underwent pretreatment magnetic resonance (MR) imaging. The values of the mean, minimum, and maximum ADC (ADC(mean), ADC(MIN), and ADC(MAX), respectively) of each tumor were preoperatively determined from several regions of interest defined in the tumors. After surgical intervention, all patients underwent irradiation and chemotherapy performed according to our hospital protocol. The patient age, symptom duration, Karnofsky performance scale score, extent of surgery, and ADC were assessed using factor analysis of overall survival. Prognostic factors were evaluated using Kaplan-Meier survival curves, the log-rank test, and multiple regression analysis with the Cox proportional hazards model. RESULTS Likelihood ratio tests confirmed that ADC(MIN) was the strongest among the three prognostic factors. Total surgical removal was the most important predictive factor for overall survival (P<0.01). ADC(MIN) was also statistically correlated with overall survival (P<0.05) and could be used to classify patients into different prognostic groups. Interestingly, ADC(MIN) was also the strongest prognostic factor (P<0.01) in the group of patients in whom total tumor removal was not possible. CONCLUSION The ADC(MIN) value obtained from pretreatment MR images is a useful clinical prognostic biomarker in patients with glioblastoma.

A Useful Antibody Panel for Differential Diagnosis Between Peritoneal Mesothelioma and Ovarian Serous Carcinoma in Japanese Cases

Malignant mesothelioma is increasing in incidence worldwide, including in Japan. However, the accurate pathologic diagnosis of pleural or peritoneal mesothelioma (PM) is sometimes difficult if adequate histologic and immunohistochemical analyses are not undertaken. The aim of this study was to identify a useful antibody panel for distinguishing PM from ovarian serous papillary adenocarcinoma (SC). We obtained 29 PMs (23 epithelioid mesotheliomas and 6 biphasic mesotheliomas) and 20 SCs from our surgical pathology files. Immunohistochemical analysis was undertaken using 13 commercially available antibodies. No significant sex differences in antigen expression among the 29 PMs were observed. The results identified calretinin and thrombomodulin as positive markers and Ber-EP4, MOC-31, CA19-9, and estrogen receptor as negative markers with relatively high sensitivity and specificity for the differential diagnosis of PM and SC. The combination of these positive and negative markers may contribute to accurate diagnosis and adequate therapy for PM and ovarian SC.

Role of PROPELLER diffusion-weighted imaging and apparent diffusion coefficient in the evaluation of pituitary adenomas

OBJECTIVE The relationship between tumor consistency and apparent diffusion coefficient (ADC) values is controversial. We evaluated the role of the ADC using an advanced diffusion-weighted imaging (DWI) technique. We employed periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) DWI acquired on a 3-T magnetic resonance imaging (MRI) scanner to assess the consistency of pituitary adenomas and examined the relationship between the ADC and the hormone secretion status of the tumors and their MIB-1 labeling index (MIB-1 LI). MATERIALS AND METHODS The study protocol was approved by our institutional review board. We retrospectively studied 24 operated patients with pituitary adenomas who had undergone PROPELLER DWI on a 3-T MRI scanner. Conventional MRI findings were expressed as the ratio of the signal intensity (SI) in the lesions to the SI of the normal white matter and the degree of contrast enhancement. Minimum-, mean-, and maximum ADC (ADCmin, ADCmean, ADCmax) values were calculated. The consistency of the tumors was determined by neurosurgeons. All surgical specimens were submitted for histological study to calculate the MIB-1 LI and the percent collagen content. Preoperative MRI-, intraoperative-, and histological findings were analyzed by a statistician. RESULTS Our study included 15 soft-, 5 fibrous-, and 4 hard tumors. Tumor consistency was strongly associated with the percent collagen content. However, neither the tumor consistency nor the percent collagen content was correlated with MRI findings or ADC values. The SI of growth hormone-producing adenomas on T2-WI was lower than of the other pituitary adenomas studied (p<0.01); no other significant difference was found in the ADC or on conventional MRI between pituitary adenomas with different secretory functions. The MIB-1 LI of pituitary adenomas was not correlated with their appearance on conventional MRI or their ADC values. CONCLUSION Using the PROPELLER DWI technique we confirmed that the ADC was not correlated with the consistency of pituitary adenomas. We also demonstrate that the ADC was not associated with the hormone-secreting status or the MIB-1 LI of pituitary adenomas.