Ovarian sex cord-stromal tumors: an immunohistochemical study including a comparison of calretinin and inhibin.

Because ovarian sex cord-stromal tumors (SCST) are morphologically heterogeneous neoplasms that are relatively infrequently encountered, their diagnosis can be difficult. Immunohistochemical staining may be useful for establishing the diagnosis in problematic cases. We studied 53 ovarian SCSTs to characterize their immunohistochemical staining pattern: 17 adult granulosa cell tumors (AGCTs), 4 juvenile granulosa cell tumors (JGCTs), 3 sex cord tumors with annular tubules (SCTATs), 9 Sertoli-Leydig cell tumors (SLCTs), 10 fibromas, 5 fibrothecomas (FTs), and 5 thecomas. In 8 of the 53 cases, the tissue studied was from a metastatic site. The immunopanel included calretinin, inhibin, WT1, cytokeratin cocktail, epithelial membrane antigen (EMA), and cytokeratin 5/6 (CK5/6). The fibromas and FTs were also tested with CD10. The extent of staining was assessed in a semiquantitative fashion and ranked on a scale of 0 through 4+. All of the tumors, except for 1 metastatic SLCT, were positive for calretinin. Forty-five of the cases (85%) stained for inhibin; 1 metastatic AGCT, 3 fibromas, and 4 FTs were negative. WT1 was present in 39 tumors (74%), with expression most prominent in the SLCTs. The cytokeratin cocktail stained 23 of the 53 tumors (43%), whereas just 1 tumor was positive for EMA (1+ in a JGCT). All tumors were negative for CK5/6, and the 15 fibromas and FTs were negative for CD10. We conclude that because cytokeratin is frequently expressed by SCSTs, in particular by granulosa cell tumors, SLCTs, and SCTATs, the inclusion of EMA in a panel may help to exclude epithelial neoplasms. In addition, WT1, present in normal granulosa cells, is expressed by a majority of SCSTs. Finally, these results demonstrate that calretinin is at least as sensitive as inhibin for ovarian SCSTs overall and that it is more sensitive than inhibin for fibromas and FTs.     

Increasing expression of serine protease matriptase in ovarian tumors: tissue microarray analysis of immunostaining score with clinicopathological parameters.

Matriptase is a type II transmembrane serine protease expressed by cells of surface epithelial origin, including epithelial ovarian tumor cells. Matriptase cleaves and activates proteins implicated in the progression of cancer and represents a potential prognostic and therapeutic target. The aim of this study was to examine the expression of matriptase in ovarian tumors and to assign clinicopathological correlations. Immunohistochemical analysis of matriptase was performed in tissue microarrays of 164 ovarian neoplasms including 84 serous adenocarcinomas, 23 mucinous adenocarcinomas, 10 endometrioid adenocarcinomas, six yolk sac tumors, 12 clear cell carcinomas, six dysgerminomas, eight granulosa cell tumors, four transitional cell carcinomas, five fibromas, and six Brenner tumors. All ovarian tumors except the fibromas and Brenner tumors showed significant expression of matriptase. The matriptase scores were significantly higher in the tumors than in their nontumor counterparts (304+/-26 for serous adenocarcinoma; 361+/-28 for mucinous adenocarcinoma; 254+/-17 for endometrioid adenocarcinoma; 205+/-19 for yolk sac tumor; 162+/-16 for clear cell carcinoma; 109+/-11 for dysgerminoma; 105+/-9 for granulosa cell tumor; and 226+/-18 for transitional cell carcinoma). Matriptase scores in serous adenocarcinoma were correlated with TNM stage and FIGO stage. Our findings demonstrate for the first time that matriptase is overexpressed in many malignant ovarian tumors. It may be a novel biomarker for diagnosis and treatment of malignant ovarian tumors.     

Inhibin immunohistochemical staining: a practical approach for the surgical pathologist in the diagnoses of ovarian sex cord-stromal tumors

Through a brief introduction of inhibin history, characteristics of the antibody against inhibin, and normal tissue distribution of alpha-inhibin expression, this comprehensive review focuses on a practical approach to using alpha-inhibin in the differential diagnosis of ovarian sex cord-stromal tumors (SCSTs). Alpha-inhibin has become a most useful immunohistochemical marker of gonadal SCST, regardless if the tumors are primary, recurrent, or metastatic. However, pathologic diagnosis of individual SCST is still based largely on morphologic criteria. Alpha-inhibin immunohistochemical (IHC) staining should be used only when a difficult morphologic diagnosis is encountered. In this perspective, alpha-inhibin and other properly selected markers should be ordered at the same time. This is simply because alpha-inhibin is not specific for SCSTs. Caution should be exercised in the interpretation of alpha-inhibin-positive cells, because a wide variety of primary and metastatic ovarian tumors may contain significant numbers of alpha-inhibin-positive stromal cells. As with other immunohistochemical stains, a panel of stains and comparison with the corresponding hematoxylin and eosin (H&E) slides is necessary, especially when staining patterns and cellular localization are in question. The antibody will not help to differentiate tumors within the category of SCST. The pattern or the intensity of staining in SCSTs does not predict tumor behavior, although there is a tendency of loss of alpha-inhibin expression in poorly differentiated Sertoli or Sertoli-Leydig cell tumors. In cases where metastatic granulosa or Sertoli-Leydig cell tumors are a concern, positive alpha-inhibin staining is diagnostic, but a negative result does not rule out metastatic disease. Calretinin has been recently recognized as a more sensitive, but less specific marker for SCSTs and it may be used to recognize an inhibin-negative SCST. In this review, we have listed nine of the most commonly encountered clinical scenarios where alpha-inhibin and other markers could be used in diagnostic surgical pathology of ovarian tumors.     

Loss of cables, a novel gene on chromosome 18q, in ovarian cancer.

Cables, a cyclin-dependent kinase (cdk) interacting protein, has recently been identified and mapped to human chromosome 18q11. Cables appears to be primarily involved in cell cycle regulation and cell proliferation. Overexpression of Cables in Hela and other cell lines inhibits cell proliferation and tumor formation. We hypothesize that loss of Cables expression is associated with ovarian cancer. To test our hypothesis, we examined Cables expression in the four most common subtypes of ovarian carcinomas: serous, endometrioid, mucinous, and clear cell. In addition, mucinous and serous borderline tumors were also included. Loss of Cables expression was observed at high frequency in ovarian serous (11 of 14 cases, 79%) and endometrioid (5 of 10 cases, 50%) carcinomas. In contrast, strong Cables staining was detected in all clear cell carcinomas (10 cases) and mucinous tumors (5 carcinomas and 5 borderline tumors). The majority of serous borderline tumors (11 of 14 cases, 79%) showed positive Cables staining, with the rest showing focal loss of Cables expression. Furthermore, RT-PCR revealed the lack of Cables mRNA in a human ovarian cancer xenograft. No correlation was noted between loss of Cables and histologic grade, tumor stage, and survival. In conclusion, our results indicate that loss of Cables is common in ovarian serous and endometrioid carcinomas and imply that Cables may be involved in the pathogenesis of these two types of ovarian carcinomas.     

Expression of calretinin and the alpha-subunit of inhibin in granular cell tumors

Granular cell tumors (GCTs) typically express S-100 protein, which has been used as a marker in differential diagnosis. Calretinin, a calcium-binding protein related structurally to S-100, and inhibin, a polypeptide hormone secreted primarily by ovarian granulosa cells and testicular Sertoli cells and functioning as an inhibitor for pituitary follicle-stimulating hormone secretion, are potentially useful but not well-evaluated markers for GCTs. We studied 43 cases of GCT with antibodies to calretinin, the inhibin alpha-subunit, and S-100 protein. All tumors were positive for inhibin alpha-subunit and S-100 protein, with 50% or more cells showing moderate to strong staining. Forty tumors (93%) were positive for calretinin, ranging from focal weak to diffuse strong staining. Enhanced staining for calretinin in the tumor cells adjacent to hyperplastic squamous epithelium was observed in 9 of 13 cases showing pseudoepitheliomatous hyperplasia. Calretinin and the inhibin alpha-subunit are useful markers for GCTs. The expression of calretinin, a primarily neuronal protein, in GCTs further supports its neural differentiation or derivation. The elevated calretinin expression in the tumor cells adjacent to the hyperplastic squamous epithelium suggests a role for calretinin in the tumor cells-squamous epithelium interaction.     

Value of mesothelial and epithelial antibodies in distinguishing diffuse peritoneal mesothelioma in females from serous papillary carcinoma of the ovary and peritoneum

AIMS: To evaluate the role of mesothelial markers (calretinin, thrombomodulin, cytokeratin 5/6, and CD44H) and carcinoma markers (polyclonal and monoclonal carcinoembryonic antigen, Leu-M1, CA-125 and Ber-EP4) in distinguishing diffuse peritoneal malignant mesothelioma from primary serous papillary adenocarcinoma of the ovary and peritoneum. METHODS AND RESULTS: Paraffin-embedded formalin-fixed blocks from 32 diffuse peritoneal mesotheliomas of epithelial subtype (all females), 20 serous papillary ovarian carcinomas and three primary peritoneal serous papillary carcinomas were studied. Calretinin and Ber-EP4 appeared to be the best positive mesothelial and carcinoma marker, respectively. Nuclear calretinin expression was identified in 28 of 32 malignant mesotheliomas with no nuclear immunoreactivity in the cohorts of serous papillary ovarian and peritoneal carcinomas, thus yielding 88% sensitivity and 100% specificity. Ber-EP4 showed 95% sensitivity and 91% specificity for serous papillary ovarian carcinoma. Thrombomodulin, cytokeratin 5/6 and CD44H immunoreactivities were seen in 18 (56%), 17 (53%) and 15 (47%) of peritoneal mesotheliomas, respectively, and in six (30%), five (25%) and five (25%) of the ovarian tumours, respectively. None of the three primary peritoneal serous papillary carcinomas expressed calretinin, thrombomodulin, cytokeratin 5/6 or CD44H. Polyclonal and monoclonal CEA, and Leu-M1 were expressed by two (10%), one (5%) and seven (35%) serous papillary ovarian carcinomas, respectively. None of the serous papillary peritoneal carcinomas expressed polyclonal CEA, monoclonal CEA or Leu-M1. CA-125 was positive in 19 (95%) and two (67%) ovarian and peritoneal carcinomas, respectively, and in eight (25%) peritoneal mesotheliomas. CONCLUSIONS: Calretinin and Ber-EP4 are useful discriminant markers in distinguishing peritoneal mesothelioma in women from serous papillary ovarian and peritoneal carcinoma. The other mesothelial markers (thrombomodulin, cytokeratin 5/6, and CD44H) and carcinoma markers (polyclonal and monoclonal CEA, and Leu-M1) yielded a too low sensitivity for practical use.     

Value of inhibin in the identification of granulosa cell tumors of the ovary

Inhibins are peptide hormones that participate in the regulation of the pituitary-gonadal feedback system and are selectively expressed by cells of sex cord—stromal derivation. To determine the efficacy of this marker for distinguishing granulosa cell tumors, 134 primary and metastatic lesions of the ovary were evaluated for expression of the alpha-subunit of inhibin in routinely processed formalin-fixed, paraffin-embedded tissue. A variety of sex cord—stromal tumors (SCST), including 35 adult and juvenile granulosa cell tumors, 14 fibroma-thecomas, and 18 other sex cord—stromal proliferations, were studied. In addition, 33 surface epithelial neoplasms, 12 germ cell tumors, 11 metastases, and 11 miscellaneous ovarian neoplastic proliferations were evaluated. Among the non-granulosa cell neoplasms, special emphasis was placed on primary neoplasms and metastases that histologically simulated granulosa cell tumors. Thirty-three of 35 (94%) granulosa cell tumors were immunoreactive compared with 2 of 12 (17%) primary ovarian endometrioid tumors, one of nine (11%) primary ovarian transitional cell (Brenner) proliferations, and 3 of 17 (18%) other primary and metastatic poorly differentiated (undifferentiated) carcinomas. In 31 of the 35 granulosa cell tumors, inhibin staining was of moderate to strong intensity or was present in at least half of the constituent cells, whereas only 2 of 33 primary surface epithelial neoplasms fulfilled the same criteria, showing weak staining of 70% to 80% of the cells. In contrast, 10 of 14 (71%) ovarian fibroma-thecomas and 17 of 18 (94%) other sex cord—stromal proliferations were positive for inhibin. Nonneoplastic luteinized stromal cells stained for inhibin in 29 of 85 cases in which they could be evaluated. The results of this study show that although it is not completely specific and cannot reliably distinguish granulosa cell tumors from fibroma-thecomas or other ovarian sex cord—stromal proliferations, inhibin can be used to help distinguish sex cord—stromal neoplasms from most primary and metastatic non-SCST. Caution should be exercised in the interpretation of inhibin-positive cells, because a wide variety of primary and metastatic ovarian tumors may contain significant numbers of positively staining luteinized cells.     

Inhibin immunohistochemistry applied to ovarian neoplasms: A novel,effective, diagnostic tool

Immunohistochemistry using monoclonal antibodies against human inhibin, a peptide hormone produced by ovarian granulosa cells to inhibit follicle-stimulating hormone (FSH), has been recently applied to diagnostic anatomic pathology. This investigation hypothesizes that inhibin immunohistochemistry will aid in the crucial clinical distinction between sex cord-stromal and other primary ovarian neoplasms. Available H&E slides and clinical information from a retrospective surgical series of 186 primary ovarian tumors were reviewed to verify diagnoses, and representative paraffin sections were immunostained with anti-inhibin (Rl monoclonal, Serotec, Kidlington, Oxford, UK). Immunoreactivity was graded as weak/strong (W/S), and the proportion of strong staining cells wascoded as follows: Sl = <10%, S2 = 10%-50%, S3 = >50%, respectively. Inhibin immunoreactivity for 137 sex cord-stromal lesions was as follows: 100% of 66 granulosa cell tumors: 80% S3, 20% S2; 100% of 17 Sertoli-stromal tumors: 90% S3, 10% S2; 100% of 13 hyperplastic follicular/stromal lesions: 90% S3, 10% S2; 100% of six steroid cell tumors: 100% S3; 90% of 18 thecomas: 40% S3, 10% S2, 10% S1, 30% W; 0% of 12 fibromas, three myxomas, and two sclerosing stromal tumors. None (0 of 49) of the other ovarian neoplasms exhibited inhibin: 22 carcinomas, 12 carcinosarcomas, seven small cell carcinomas, six germ cell tumors, and two lymphomas. In the typical case, the distinction between sex cord-stromal and other ovarian neoplasms requires nothing more than routine pathological examination. In diagnostically challenging cases, our data indicate that inhibin immunohistochemistry is a very useful adjunct because granulosa and sertoli-stromal tumors are positive whereas other potential mimickers have been negative thus far.     

Intermediate filaments cytokeratin and vimentin in ovarian sex cord-stromal tumours with correlative studies in adult and fetal ovaries

The expression of the intermediate filaments cytokeratin and vimentin were studied immunohistochemically in a series of ovarian sex cord-stromal tumours (26 adult and juvenile granulosa cell tumours, 11 thecomas, six fibromas, three Sertoli-Leydig cell tumours and 1 sex cord tumour with annular tubules). Contrary to previous reports, granulosa cell tumours expressed cytokeratins as well as vimentin. Thecomas and fibromas expressed vimentin only. In Sertoli-Leydig cell tumours and the sex cord tumour with annular tubules, both cytokeratins and vimentin were detected. Correlative studies in adult ovaries showed that patterns of expression in non-neoplastic granulosa, thecal and stromal cells correspond to their neoplastic counterparts. Investigation of fetal ovaries demonstrated that these patterns of intermediate filament expression exist from relatively early stages of development. Ovarian surface epithelium and rete ovarii, like granulosa cells, co-expressed cytokeratin and vimentin. The demonstration of cytokeratins in granulosa cells and the reported presence of desmosomes and tonofilaments, suggests the epithelial nature of these cells although not clarifying their histogenesis. The presence of both these intermediate filaments in granulosa and Sertoli-Leydig cell tumours as well as in some ovarian carcinomas which may mimic them, limits their value in differential diagnosis between these tumour groups.     

Immunoexpression of inhibin alpha subunit, inhibin/activin betaA subunit and CD99 in ovarian tumors

OBJECTIVE: Anti-inhibin alpha and inhibin/activin betaA subunit and anti-CD99 monoclonal antibodies (mAbs) have recently been demonstrated to be able to label ovarian granulosa cells; thus, they may be of value in the diagnosis of granulosa cell tumors. The present study aimed to determine what combination of these mAbs may be useful for the differential diagnosis of sex cord-stromal tumors of ovary. DESIGN: Immunohistochemical analyses with anti-inhibin alpha and inhibin/activin betaA subunit antibody and anti-CD99 mAb were performed on 42 ovarian tumors, including sex cord-stromal tumors (29), ovarian epithelial cancers (10), and Krukenberg tumors (3). RESULTS: All sex cord-stromal tumors were positive for inhibin alpha subunit, and 17 cases (58.6%) of sex cord-stromal tumors were immunoreactive for inhibin/activin betaA subunit. Epithelial tumors and Krukenberg tumors were all negative for inhibin/activin betaA subunit except mucinous carcinoma, which showed strong cytoplasmic immunoreactivity. All sex cord-stromal tumors except one granulosa cell tumor showed membranous staining for CD99. A case of serous carcinoma and a case of mucinous carcinoma were positive for CD99, and the remaining epithelial tumors and Krukenberg tumor were all negative for CD99. CONCLUSIONS: The results of immunohistochemical analysis, together with literature review, suggest that inhibin alpha subunit may be a useful diagnostic marker for sex cord-stromal tumor of the ovary. In addition, anti-CD99 antibody may be useful for the differential diagnosis between ovarian tumors. Inhibin/activin betaA subunit has a limited usefulness in the differential diagnosis of ovarian tumor because of its wider immunoreactivity for both sex cord-stromal tumors and mucinous carcinomas. The differential diagnosis of sex cord-stromal tumors of the ovary would be better made with a combined use of both anti-inhibin alpha subunit and anti-CD99 mAbs.     

E-cadherin nuclear staining is useful for the diagnosis of ovarian adult granulosa cell tumor

We recently have demonstrated nuclear localization of E-cadherin in ovarian adult granulosa cell tumors (Histopathology 2011;58:423). The purpose of the present study is to investigate the diagnostic utility of E-cadherin nuclear staining for the differential diagnosis between ovarian adult granulosa cell tumor and its morphological mimics. Tissue samples taken from 81 ovarian tumors and 20 extraovarian tumors were immunohistochemically stained using monoclonal anti-E-cadherin antibody recognizing cytoplasmic domain (clone 36 supplied by BD Biosciences, San Jose, CA). The ovarian tumors consisted of 30 adult granulosa cell tumors, 3 Sertoli-stromal cell tumors, 14 fibrothecomas, 5 carcinoid tumors, 1 large cell neuroendocrine carcinoma, 18 endometrioid adenocarcinomas, and 10 poorly differentiated serous adenocarcinomas. Extraovarian tumors consisted of 16 uterine endometrial stromal neoplasms and 4 pulmonary small cell carcinomas. Only tumor cells with nuclear staining were considered positive in this study. Ninety percent of adult granulosa cell tumors, 67% of Sertoli-stromal cell tumors, 64% of fibrothecomas, 75% of endometrial stromal neoplasms, 75% of small cell carcinomas, and the one large cell neuroendocrine carcinoma showed E-cadherin nuclear expression, whereas all the ovarian carcinoid tumors, endometrioid adenocarcinomas, and poorly differentiated serous adenocarcinomas were negative. E-cadherin nuclear staining is useful in distinguishing between adult granulosa cell tumors and ovarian adenocarcinomas or carcinoid tumors. However, it is of limited use for distinguishing between adult granulosa cell tumors and endometrial stromal neoplasms or small cell carcinomas. E-cadherin should be included in the immunohistochemical panel for an accurate diagnosis of ovarian adult granulosa cell tumors.     

Immunohistochemistry as a diagnostic aid in the evaluation of ovarian tumors

Aspects of immunohistochemistry (IHC), which are useful in the diagnosis of ovarian tumors (mostly neoplasms but also a few tumor-like lesions), are discussed. The topic is first approached by considering the different growth patterns and cell types that may be encountered. Then a few other specific situations in which IHC may assist are reviewed. Selected findings largely, or only, of academic interest are also mentioned. One of the most common situations in which IHC may aid is in the evaluation of tumors with follicles or other patterns which bring a sex cord-stromal tumor into the differential. The distinction between a sex cord tumor and an endometrioid carcinoma with sex-cord-like patterns may be greatly aided by the triad of epithelial membrane antigen (EMA), inhibin, and calretinin, the latter two being typically positive and EMA negative in sex cord tumors, the converse being typical of endometrioid carcinoma. It should be emphasized that granulosa cell tumors may be inhibin negative and, albeit less specific, calretinin is more reliable in evaluating this particular issue. Lack of staining for inhibin and calretinin may also be supportive in leading to consideration of diverse other neoplasms that may form follicles, including metastatic tumors as varied as carcinoid and melanoma. The well-known staining of the latter neoplasm for S-100 protein and HMB-45 may be very helpful in evaluating melanomas with follicular or other unusual patterns, a challenging aspect of ovarian tumor interpretation. The most common monodermal teratoma, struma ovarii, usually has an overt follicular pattern and is easily recognized, but recognition of unusual appearances ranging from oxyphilic to clear cell to various patterns of malignant struma may be greatly aided by a thyroglobulin or TTF 1 stain. IHC for neuroendocrine markers may assist in the diagnosis of primary and metastatic carcinoid tumor. The broad differential diagnosis of glandular neoplasms with an endometrioid-pseudoendometrioid morphology, or mucinous cell type, has been the subject of much exploration in recent years, particularly the distinction between primary and metastatic neoplasms. The well-known CK7 positive, CK20 negative phenotype of primary endometrioid carcinoma, and the converse profile in most metastatic large intestinal adenocarcinomas with a pseudoendometrioid morphology, has been much publicized but albeit an appropriate supportive adjunct in many cases, exceptions from the typical staining pattern may be encountered. It is even less helpful in the case of primary versus metastatic mucinous neoplasia. Evaluation of the expression of mucin gene products has shown mixed, essentially unreliable, results. Experience with other new markers, such as CDX-2, villin, beta catenin, and P504S (racemase), is limited but is in aggregate promising with regard to providing some aid in this area. The rare differential of metastatic cervical adenocarcinoma versus primary ovarian mucinous or endometrioid carcinoma may be aided by strong p16 staining of the former. Staining for alpha-fetoprotein may aid in confirming the diagnosis of endometrioid-like (and hepatoid) variants of yolk sac tumor. Ependymoma of the ovary may also have an endometrioid-like glandular pattern, but positive stains for glial fibrillary acidic protein contrast with the negative results in others neoplasms with a similar pattern. Immunostains may be very helpful in the evaluation of oxyphilic tumors and tumor-like lesions and in some unusual forms of clear cell neoplasia, such as clear cell struma, both subjects being reviewed herein. Immunostains may highlight both the presence and extent of epithelial cells in a variety of circumstances, including microinvasive foci in cases of serous borderline tumors and mucinous carcinomas, and in determining the extent of carcinoma cells and reactive cells within mural nodules of mucinous neoplasms. As in tumor pathology in general, various markers may be crucial in the diagnosis of small round cell tumors of the ovary, and familiar markers of epithelial, lymphoid, leukemic, and melanocytic neoplasms may assist in the analysis of high grade tumors with a poorly differentiated carcinoma, lymphoma-granulocytic sarcoma, malignant melanoma differential. The evaluation of ovarian cystic lesions may be aided by thyroglobulin or TTF 1 (cystic struma), glial fibrillary acid protein (ependymal cysts), and inhibin-calretinin (follicle cysts and unilocular granulosa cell tumors). Stains for trophoblast markers may occasionally aid in the evaluation of germ cell tumors, although routine stains should usually suffice; they may be of academic interest in confirming trophoblastic differentiation in some high grade surface epithelial carcinomas.     

Characterization of the specificity by immunohistology of a monoclonal antibody to a novel epithelial antigen of ovarian carcinomas

An immunohistological study, using the avidin-biotin-peroxidase complex method, was carried out to define the reactivity profile of a murine monoclonal antibody, MOv2, which recognizes a novel glycoprotidic antigen associated with ovarian epithelial tumors. Among the primary ovarian tumors tested, MOv2 immunostained 93% of mucinous and 75% of serous cystadenomas, 100% of mucinous, 81% of serous and 73% of endometrioid carcinomas. Undifferentiated and clear cell tumors revealed more limited reactivity with the antibody, whereas ovarian sex cord-stromal and germinal tumors were immunonegative. Positive reactions were also documented in omental metastases from primary ovarian carcinomas. No immunoreactivity was detected in normal ovarian epithelium, whereas the cells lining Walthard's nests adjacent to the fallopian tubes and a variety of normal epithelia were consistently immunolabeled. These included the lining epithelia of the gastrointestinal tract, bronchi and endocervix, and the epithelium of salivary, biliary and pancreatic ducts and sweat glands. To a lesser extent, positive reactions were detected in other surface epithelia, such as squamous and transitional epithelia. Among tumors other than ovarian, MOv2 consistently reacted with adenocarcinomas and squamous cell carcinomas from different sites, most notably breast, lung and gastrointestinal tract, and with transitional cell carcinomas. In contrast, no staining was demonstrated in non-epithelial malignancies. The antigen defined by MOv2 may be operationally useful as a marker of epithelial lineage in tumor histopathology. Its pattern of immunohistochemical distribution indicates that an antigenic phenotype shared by normal surface epithelia and non-ovarian carcinomas is strongly associated with common epithelial neoplasms of the ovaries.     

Value of A103 (melan-A) immunostaining in the differential diagnosis of ovarian sex cord stromal tumours

AIMS: To assess A103 (melan-A) immunoreactivity in a range of ovarian sex cord stromal tumours and to evaluate it for the differential diagnosis of other neoplasms. METHODS: Paraffin embedded tissue sections from 45 sex cord stromal tumours and 44 potential histological mimics were examined immunohistochemically using the antibody A103. The sex cord stromal group included 21 adult granulosa cell tumours (AGCT), two juvenile granulosa cell tumours (JGCT), eight tumours showing Sertoli cell or Sertoli-Leydig cell differentiation, two unclassified tumours, two gonadoblastomas, one sex cord tumour with annular tubules, two steroid cell tumours, five thecomas/fibrothecomas, and two sclerosing stromal tumours. The histological mimics include 14 primary ovarian carcinomas, 13 metastatic carcinomas, four carcinoid tumours, four lymphomas, three endometrioid stromal sarcomas, two ovarian tumours of probable Wolffian origin, and one case each of small cell carcinoma, desmoplastic small round cell tumour, melanoma, and primitive neuroectodermal tumour. RESULTS: A103 immunoreactivity was identified in 25 sex cord stromal tumours including 10 AGCT, two JGCT, six Sertoli/Sertoli-Leydig cell tumours, two steroid cell tumours, three thecomas/fibrothecomas, and two sclerosing stromal tumours. Of the potential histological mimics, staining was present only in the two ovarian tumours of probable Wolffian origin and the melanoma. Immunoreactive stromal cells were noted in a minority of cases. Normal hilus cells and rete ovarii epithelium also expressed A103. CONCLUSIONS: A103 is a moderately sensitive and specific marker of sex cord stromal differentiation within the range of tumours examined in this study and as such is a valuable adjunct to other immunocytochemical markers in the assessment of diagnostically problematic ovarian tumours. The staining of normal and neoplastic Wolffian elements merits further investigation.     

Expression and mutational analysis of c-kit in ovarian surface epithelial tumors

Coexpression of Kit ligand and c-kit has been reported in some gynecologic tumors. To determine whether imatinib mesylate is useful in ovarian epithelial tumors, we performed immunohistochemical and mutational analysis. The cases consisted of 33 cases, which included 13 serous cystadenocarcinomas, 1 borderline serous tumor, 8 mucinous cystadenocarcinomas, 6 borderline mucinous tumors and 5 clear cell carcinomas. Five cases of serous cystadenoma and 5 cases of mucinous cystadenoma were also included. In the immunohistochemical study, 3 cases (3/6, 50%) of borderline mucinous cystic tumor and two cases (2/8, 25%) of mucinous cystadenocarcinoma show positive staining for KIT protein. Only one case (1/13, 7.7%) of serous cystadenocarcinoma had positive staining. On mutational analysis, no mutation was identified at exon 11. However, two cases of borderline mucinous tumors and one case of mucinous cystadenocarcinoma had mutations at exon 17. In these cases, the immunohistochemistry also shows focal positive staining at epithelial component. Although, KIT protein expression showed higher incidence in mucinous tumors than serous tumors, they lack KIT-activating mutations in exon 11. Thus, ovarian surface epithelial tumors are unlikely to respond to imatinib mesylate.     

Immunohistochemical studies of steroidogenic enzymes (aromatase, 17 alpha-hydroxylase and cholesterol side-chain cleavage cytochromes P-450) in sex cord-stromal tumors of the ovary

Aromatase, 17 alpha-hydroxylase, and cholesterol side-chain cleavage P-450 cytochromes (P-450AROM, P-450(17 alpha,) and P-450SCC, respectively) were immunohistochemically localized in nine granulosa cell tumors, 15 thecomas, ten Sertoli-Leydig cell tumors, two steroid cell tumors, five fibromas, and five sclerosing stromal tumors. In the thecomas, P-450SCC and P-450(17 alpha) were positive in luteinized theca cells and in cells with vacuolated cytoplasm, while P-450AROM was not observed. In the steroid cell tumors, all the P-450 cytochromes were intensely stained. P-450SCC and P-450(17 alpha) were present in cells with vacuolated cytoplasm in two cases of sclerosing stromal tumor. P-450AROM was weakly demonstrated in one of the granulosa cell tumors. P-450(17 alpha,) P-450SCC, and P-450AROM were all faintly stained in the Sertoli-Leydig cell tumors. No P-450 cytochrome immunoreactivity was observed in any fibroma.     

Expression of Rsf-1, a chromatin-remodeling gene, in ovarian and breast carcinoma

Rsf-1 protein is a member of a chromatin-remodeling complex that plays an important role in regulating gene expression and cell proliferation. Our previous study showed that Rsf-1 was an amplified gene that participated in the development of ovarian serous carcinoma. To further elucidate the role of Rsf-1 in ovarian cancer, we studied Rsf-1 immunoreactivity in 294 ovarian tumors of various histologic types. Because the Rsf-1 amplicon overlaps an amplified region reported in breast cancer, we included 782 neoplastic and normal breast tissues for comparison. Immunohistochemistry was performed on tissue microarrays using a 4-tiered scoring system. Overexpression of Rsf-1 was defined as a nuclear immunointensity of 3+ to 4+ because of a strong correlation between 3+ and 4+ immunointensity and Rsf-1 gene amplification, based on our previous fluorescence in situ hybridization analysis. Rsf-1 overexpression was observed in 25% of high-grade ovarian serous carcinomas and in only rare cases (<7%) of low-grade ovarian serous, ovarian endometrioid, and invasive breast carcinomas but not in any ovarian serous borderline tumors, ovarian clear cell carcinomas, ovarian mucinous carcinomas, intraductal carcinomas of the breast, and normal ovaries and breast tissues. Thus, overexpression of Rsf-1 was significantly associated with high-grade ovarian serous carcinoma (P < .05), as compared with other types of ovarian tumors and breast carcinomas. Our results provide evidence that Rsf-1 expression is primarily confined to high-grade serous carcinoma, the most aggressive ovarian cancer. Because Rsf-1 overexpression occurs in only a small number of breast carcinomas, it is unlikely that Rsf-1 is a critical gene in the development of breast carcinoma.     

Expression of Tn and sialyl-Tn antigens in tumor tissues of the ovary.

The expression of sialyl-Tn and Tn antigens in various benign, borderline, and malignant ovarian tumors was examined immunohistochemically using newly developed antibodies specific for sialyl-Tn and Tn antigens. Sialyl-Tn antigen was detected in only one benign tumor, a mucinous adenoma that showed faint cytoplasmic staining in a few cells. However, sialyl-Tn was present in 5 of 12 serous borderline tumors, 10 of 19 mucinous borderline tumors, 10 of 13 serous adenocarcinomas, 15 of 16 mucinous adenocarcinomas, 14 of 15 endometrioid adenocarcinomas, and 7 of 7 clear cell carcinomas of the ovary. The antigen expression was observed throughout the cytoplasm of cancer cells and in the apical cytoplasm and luminal contents of some glands. The incidence and intensity of staining for sialyl-Tn antigen were higher in malignant tumors than in borderline tumors, but these results did not correlate with the histologic classification or differentiation. Coexpression of sialyl-Tn antigen and Tn antigen was observed in two serous adenocarcinomas, six mucinous borderline tumors, five mucinous adenocarcinomas, eight endometrioid, and seven clear cell carcinomas. In no case was Tn antigen expressed without concomitant sialyl-Tn antigen expression. Accumulation of sialyl-Tn antigen seems to be an early event of carcinogenesis of the ovary.     

Molecular pathogenesis and extraovarian origin of epithelial ovarian cancer--shifting the paradigm

Recent morphologic, immunohistochemical, and molecular genetic studies have led to the development of a new paradigm for the pathogenesis and origin of epithelial ovarian cancer based on a dualistic model of carcinogenesis that divides epithelial ovarian cancer into 2 broad categories designated types I and II. Type I tumors comprise low-grade serous, low-grade endometrioid, clear cell and mucinous carcinomas, and Brenner tumors. They are generally indolent, present in stage I (tumor confined to the ovary), and are characterized by specific mutations, including KRAS, BRAF, ERBB2, CTNNB1, PTEN, PIK3CA, ARID1A, and PPP2R1A, which target specific cell signaling pathways. Type I tumors rarely harbor TP53 mutations and are relatively stable genetically. Type II tumors comprise high-grade serous, high-grade endometrioid, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinomas. They are aggressive, present in advanced stage, and have a very high frequency of TP53 mutations but rarely harbor the mutations detected in type I tumors. In addition, type II tumors have molecular alterations that perturb expression of BRCA either by mutation of the gene or by promoter methylation. A hallmark of these tumors is that they are genetically highly unstable. Recent studies strongly suggest that fallopian tube epithelium (benign or malignant) that implants on the ovary is the source of low-grade and high-grade serous carcinoma rather than the ovarian surface epithelium as previously believed. Similarly, it is widely accepted that endometriosis is the precursor of endometrioid and clear cell carcinomas and, as endometriosis, is thought to develop from retrograde menstruation; these tumors can also be regarded as involving the ovary secondarily. The origin of mucinous and transitional cell (Brenner) tumors is still not well established, although recent data suggest a possible origin from transitional epithelial nests located in paraovarian locations at the tuboperitoneal junction. Thus, it now appears that type I and type II ovarian tumors develop independently along different molecular pathways and that both types develop outside the ovary and involve it secondarily. If this concept is confirmed, it leads to the conclusion that the only true primary ovarian neoplasms are gonadal stromal and germ cell tumors analogous to testicular tumors. This new paradigm of ovarian carcinogenesis has important clinical implications. By shifting the early events of ovarian carcinogenesis to the fallopian tube and endometrium instead of the ovary, prevention approaches, for example, salpingectomy with ovarian conservation, may play an important role in reducing the burden of ovarian cancer while preserving hormonal function and fertility.