MOC-31 aids in the differentiation between adenocarcinoma and reactive mesothelial cells.

BACKGROUND: Evaluation of effusion specimens for the presence of adenocarcinoma often is complicated by the presence of reactive mesothelial cells that can mimic adenocarcinoma. Ancillary studies, in particular immunohistochemistry, can be helpful in making this distinction. MOC-31 is an antibody that recently was reported to be useful in distinguishing adenocarcinoma from mesothelioma in tissue specimens. In this study we examined the utility of this antibody in pleural effusions. METHODS: Eighty-nine archival, formalin fixed, paraffin embedded cell blocks representing 59 adenocarcinomas, 12 other neoplasms (including 6 mesotheliomas), and 18 reactive effusions were retrieved. After protease digestion, recut slides were immunostained with the MOC-31 antibody utilizing a modified avidin-biotin complex technique. Only membrane-based reactivity was considered as positive. RESULTS: In two adenocarcinomas there was insufficient material remaining in the cell block. Among the 57 remaining cases, reactivity was observed in 54 cases. Reactivity also was observed in one of six mesotheliomas and one small cell carcinoma. The remaining cases, including all 18 reactive effusions, were nonreactive. In distinguishing adenocarcinoma from reactive mesothelial cells, the presence of MOC-31 reactivity was found to be 95% sensitive and 100% specific with a positive predictive value of 100% and a negative predictive value of 95%. CONCLUSIONS: MOC-31 is useful in differentiating between adenocarcinoma and reactive mesothelial cells in pleural effusion specimens. Cancer (Cancer Cytopathol)

HER-2/neu amplification and overexpression in endometrial carcinoma.

HER-2/neu is a proto-oncogene associated with poor prognosis in women with breast and ovarian carcinoma. The significance of HER-2/neu in endometrial carcinoma is less clearly established. The authors compared HER-2/neu gene amplification using fluorescence in situ hybridization and protein overexpression using immunohistochemistry with survival in patients with endometrial carcinoma. Fluorescence in situ hybridization and immunohistochemical staining were performed on 72 formalin-fixed, paraffin-embedded endometrial carcinoma specimens. Vysis combination HER-2/neu and centromere 17 probe mixture was applied to isolated tumor cell nuclei. A minimum of 200 nuclei were scored for each specimen using standard signal enumeration criteria. A specimen was considered amplified with 5% or greater amplified nuclei. Tissue sections were immunostained with polyclonal antibody against p185erb-2 transmembrane glycoprotein. Immunohistochemical reactivity was scored on a three-tiered scale. HER-2/neu gene amplification and protein overexpression were detected in 15 of 72 (21%) and 12 of 72 (17%) of the specimens, respectively, with 2 cases of normal copy overexpression and 5 cases of amplification without overexpression. Both amplification and overexpression were associated with higher grade tumors. Amplification was associated with clear cell and serous subtypes (p = 0.002), and overexpression with only clear cell type (p = 0.006). Using the proportional hazards model of survival, amplification was found to have significant negative predictive value beyond stage, grade, and cell type (p = 0.002). HER-2/neu gene amplification as detected by fluorescence in situ hybridization in archival material has significant prognostic value.

An immunohistochemical study of Na+/I- symporter in human thyroid tissues and salivary gland tissues.

The human Na+/I- symporter (hNIS) is the plasma membrane protein that mediates active iodide uptake into several tissues, such as the thyroid and salivary glands. To study the distribution and cellular localization of the hNIS protein, we have generated a polyclonal antibody that could detect the hNIS protein by immunohistochemical staining on tissue sections. In normal thyroids, hNIS expression is heterogeneous, and it is only detected in sporadic thyrocytes of a given follicle. The hNIS protein was not detected in thyroid carcinomas, yet it was detected in the majority of thyrocytes in Graves' thyroids. In salivary glands, hNIS protein was not detected in acinar cells, but it was detected in ductal cells. The hNIS proteins are clustered in the basal and lateral membranes in cells stained positive for hNIS.

Retinoblastoma protein expression in ovarian epithelial neoplasms.

Progress has been made in identifying the molecular changes that occur in ovarian carcinoma; still our understanding of these changes and their interactions remains incomplete. In the present study the authors examined the expression of retinoblastoma protein, a tumor suppressor protein, in a spectrum of ovarian epithelial tumors including cystadenomas, low-malignant-potential tumors, and carcinomas. A heterogeneous pattern of reactivity was observed in all of the cystadenomas, in all of the low-malignant-potential tumors, and in a majority (27/34) of the carcinomas. The remaining carcinomas showed either a complete absence of reactivity or a pattern of altered reactivity characterized by areas of tumor with intact reactivity adjacent to zones of tumor with a complete absence of reactivity. There was no significant association between grade or stage and absent/altered reactivity. We conclude that alterations of retinoblastoma protein expression are uncommon in ovarian carcinoma.

Anti-MOC-31: a potential addition to the pulmonary adenocarcinoma versus mesothelioma immunohistochemistry panel.

MOC-31 expression has recently been advocated as an immunohistochemical marker for distinguishing mesothelioma from adenocarcinoma in tissue sections. We studied formalin-fixed, paraffin-embedded tissue from 23 pleural mesotheliomas and 23 primary pulmonary adenocarcinomas for immunoreactivity with anti-MOC-31, a human epithelial-related antigen. All of the 23 adenocarcinomas strongly expressed the marker, whereas only one of the mesotheliomas showed weak reactivity. These results demonstrate the usefulness of anti-MOC-31 in differentiating pulmonary adenocarcinoma from mesothelioma.

Retinoblastoma protein expression in endometrial hyperplasia and carcinoma.

The retinoblastoma (RB) gene was the first defined tumor suppressor gene. While originally described in retinoblastoma, more recently alterations in RB have been described in a number of other human neoplasms and there has been a suggestion that alteration of RB may play a significant role in the development of endometrial carcinoma. We examined RB protein expression by immunohistochemistry in a series of cases including normal endometrium, endometrial hyperplasia, and endometrial carcinoma. A relatively homogeneous pattern of staining was observed in proliferative endometrium, while weak or absent reactivity was noted in secretory endometrium. A heterogeneous pattern of reactivity was observed in 10/10 cases of hyperplasia, 66/70 cases of endometrial adenocarcinoma, and 7/7 cases of uterine carcinosarcoma. An altered pattern of reactivity was observed in the remaining 4/70 cases of adenocarcinoma. All of the cases with altered reactivity were high grade neoplasms. We conclude that alteration of RB protein expression is uncommon in endometrial adenocarcinoma and when it does occur, it may represent a late event in carcinogenesis.

bcl-2 expression in endometrial hyperplasia and carcinoma.

The bcl-2 gene codes for a protein which functions to inhibit apoptotic cell death. bcl-2 overexpression was originally described in follicular lymphoma, but more recently bcl-2 expression has been observed in a variety of other human neoplasms. In this study we used immunohistochemistry to examine bcl-2 protein expression in endometrial hyperplasia and carcinoma. bcl-2 protein was observed in 4/4 cases of complex hyperplasia, 1/4 cases of complex atypical hyperplasia, and 10/29 cases of carcinoma. The staining observed in the cases of complex atypical hyperplasia and carcinoma was focal and less intense than the reactivity of normal proliferative endometrium. We conclude that bcl-2 protein is seldom overexpressed in complex atypical hyperplasia or carcinoma of the endometrium. Rather, in many cases of endometrial carcinoma bcl-2 expression appears to be decreased.