Inhibin is more specific than calretinin as an immunohistochemical marker for differentiating sarcomatoid granulosa cell tumour of the ovary from other spindle cell neoplasms

Cytologic features of sex cord-stromal tumors in women

BACKGROUND

Gynecologic sex cord-stromal tumors (SCSTs) arise from sex cords of the embryonic gonad and may display malignant behavior. We describe the cytomorphologic features of SCSTs in females, including adult and juvenile granulosa cell tumors (AGCTs and JGCTs), Sertoli-Leydig cell tumors (SLCTs), and steroid cell tumors (SCTs).

METHODS

We retrieved available cytology slides from females with a histologic diagnosis of sex cord-stromal tumor between 2009 and 2020 from institutional archives and reviewed their cytoarchitectural features.

RESULTS

There were 25, 2, 2, and 1 cytology specimens from 19, 2, 2, and 1 patients (aged 7-90 years, median 57 years) with AGCT, JGCT, SLCT, and SCT, respectively. Features common to all SCSTs included 3-dimensional groups, rosettes, rare papillary fragments, abundant single cells and naked nuclei. Rosettes and a streaming appearance of cell groups were only seen in AGCTs, which also rarely featured eosinophilic hyaline globules and metachromatic stroma. AGCTs exhibited high nuclear:cytoplasmic (N:C) ratios, with mild nuclear pleomorphism, uniform nuclei with finely granular chromatin, nuclear grooves and small nucleoli; in contrast, other SCSTs lacked rosettes and nuclear grooves and had generally lower N:C ratios, greater nuclear pleomorphism, coarse chromatin and more abundant cytoplasm. Mitotic figures, necrosis, and inflammation were rarely identified.

CONCLUSIONS

AGCTs show cytomorphologic features that are distinct from those of other SCSTs. Careful evaluation of the cytological features and ancillary studies (eg, immunochemistry for FOXL2, inhibin and calretinin, or sequencing for FOXL2 mutations) can aid in the accurate diagnosis of these tumors.

Uterine tumor resembling ovarian sex cord tumor: a clinicopathological and immunohistochemical analysis of two cases and a literature review

A uterine tumor resembling an ovarian sex cord tumor (UTROSCT) is a rare type of neoplasm that is almost thoroughly differentiated towards ovarian sex cord elements. Because of abnormal uterine bleeding, a 64-year-old postmenopausal woman received total abdominal hysterectomy with bilateral salpingo-oophorectomy. Under a microscope, the tumor cells showed an anastomosing fascicular and trabecular pattern with a reticular architecture. Immunohistochemistry showed that the tumor cells were positive for calretinin, Wilm’s tumor-1, and vimentin. A 33-year-old woman who suffered from menorrhagia, and was treated for bilateral salpingectomy, total abdominal hysterectomy, and bilateral ovarian biopsy, was also studied. Using histology, the patient was diagnosed with UTROSCT as shown by CD99, smooth muscle actin, calretinin, vimentin, and desmin expression. As a type of rare uterine tumor, UTROSCT can be diagnosed based on morphological and immunohistochemical conditions. Generally, these tumors are benign, but can easily relapse through incomplete resection. Hysterectomy should be performed after completion of family planning.

Retiform Sertoli-Leydig Cell Tumor in a 38-Year-Old Woman: A Case Report, Retrospective Review, and Review of Current Literature

Ovarian sex cord-stromal tumors arise from the stromal cells that surround and support the oocytes. Sertoli-Leydig cell tumors belong to this category of ovarian neoplasms. We present the case of a 38-year-old woman who was found to have a right ovarian mass. The mass was resected and diagnosed as Stage I Sertoli-Leydig cell tumor, retiform variant, following histopathologic and immunohistochemical examination. This case is unusual given the rarity of the retiform variant of Sertoli-Leydig cell tumor and the atypically older age of 38 years at presentation.

The Utility of Immunohistochemistry in the Differential Diagnosis of Gynecologic Disorders

Context

Immunohistochemistry has assumed an increasing role in the identification and characterization of gynecologic disorders including lesions with deceptively bland morphology, uncommon and underdiagnosed neoplasms, and neoplasms with specific genetic alterations associated with overexpression or loss of expression of specific proteins. The diagnostic accuracy has been significantly improved owing to the discovery and increasing experience with the tumor-associated biomarkers, and the increasing demand for precise tumor classification to assess suitability for the expanding therapeutic modalities including clinical trials.

Objective

To differentiate lesions of the gynecologic tract through the use of effective immunohistochemical panels.

Data Sources

Literature review and authors' personal practice experience.

Conclusions

The application of diagnostic and prognostic immunohistochemical panels has enabled pathologists to better guide therapeutic decisions and to better predict the clinical outcome. It is now well established that the use of ancillary testing, including immunohistochemistry, has a significant power in the identification, differentiation, and classification of reactive, premalignant, and malignant gynecologic disorders. This article discusses the utilities and pitfalls of the commonly used immunohistochemical markers in the context of overlapping morphologic features encountered in the uterus, ovaries, and fallopian tubes.

Endometrial/ioid Stromal Tumors and Related Neoplasms of the Female Genital Tract

Endometrial/ioid stromal tumors comprise a spectrum of mesenchymal neoplasms, ranging from benign to low-grade malignancy to undifferentiated sarcomas, which occur predominantly in the uterus but may rarely originate at extrauterine sites, most commonly in the ovary. These tumors and their morphologic variants are important to recognize as they often cause diagnostic difficulties. This review focuses on the diagnostic criteria and differential diagnosis, including the role of immunohistochemistry.

Cellular Fibromatous Neoplasms of the Ovary

Many ovarian tumors composed primarily of fibroblastic cells are fibromas of usual type, and generally do not pose diagnostic difficulty. These tumors can be diagnosed accurately in most instances based on morphology without needing immunohistochemistry. Approximately 10% of fibromatous neoplasms, however, exhibit increased cellularity and mitotic activity, and, in the presence of the former or both features, are classified as cellular fibroma or mitotically active cellular fibroma. Distinguishing these entities from fibrosarcoma, an exceptionally uncommon ovarian malignancy, is important. This article reviews fibromatous ovarian tumors, emphasizing cellular fibromas and their differential diagnosis.

Immunohistochemical Markers of Value in the Diagnosis of Mesenchymal Lesions of the Female Genital Tract

Pure mesenchymal tumors may occur anywhere in the female genital tract, but they are most common in the uterine corpus, leiomyoma being by far the most prevalent. These tumors, and other uncommon mesenchymal lesions within the uterine corpus and elsewhere in the female genital tract, may result in several diagnostic problems. Morphology remains paramount and, in most cases, an unequivocal diagnosis can be made based on examination of the hematoxylin and eosin stained sections, combined with an appreciation of the clinical and gross pathologic features. In difficult cases, immunohistochemistry can significantly contribute to the final diagnosis. In this article, the immunohistochemistry of neoplastic and nonneoplastic mesenchymal lesions of the female genital tract is discussed site by site, concentrating on markers that are of value in diagnosis and in differential diagnosis. The immunophenotype of mixed epithelial and mesenchymal neoplasms and pure epithelial neoplasms with a component of spindle cells is discussed, where appropriate, because these can enter into the differential diagnosis of a pure mesenchymal lesion.

Calretinin: diagnostic utility in the female genital tract

The utility of calretinin was first described in the diagnosis of mesothelioma. In the female genital tract, calretinin was initially reported in Wolffian remnants and related lesions and later used in the diagnosis of sex cord stromal tumors of the ovary, endometrial stromal tumors with sex cord-like differentiation, and uterine tumors resembling sex cord tumors of the ovary. This review discusses calretinin expression in normal tissues of the female genital tract and highlights its potential utility in the diagnosis of these subsets of neoplasms with emphasis to tumors that may constitute a problem in their differential diagnosis. In particular, the limited utility of calretinin in the diagnosis of sex cord stromal tumors of the ovary, in the differential diagnosis between mesothelioma and serous tumors involving the ovary and/or peritoneum, and in the differential diagnosis between Wolffian lesions and endometrial carcinoma are addressed.

CD10 Expression in Pure Stromal and Sex Cord-Stromal Tumors of the Ovary

CD10 has been recently advocated as a good immunohistochemical marker for endometrial stromal tumors. Metastatic endometrial stromal tumors to the ovary and primary endometrioid stromal sarcomas may show overlapping histological features with pure stromal and sex cord-stromal tumors (SCSTs). We investigated CD10 expression in a large series of pure stromal and SCSTs of the ovary to ascertain whether CD10 may aid in this differential diagnosis. Archival material from 11 fibromas, 10 thecomas, 10 sclerosing stromal tumors (SSTs), 10 adult granulosa cell tumors (AGCTs), 4 luteinized AGCTs, 9 juvenile granulosa cell tumors (JGCTs), 9 Sertoli cell tumors, 9 Sertoli-Leydig cell tumors, 11 sex cord tumors with annular tubules, 10 steroid cell tumors (StCTs), and 8 fibrosarcomas of the ovary were immunostained for CD10. The percentage of cells stained (<5%, 5%-39%, 40%-75%, and >75%) and intensity of staining (1+, 2+, 3+) were evaluated. CD10 was expressed in 7 of 10 thecomas (4 with 5%-75% and mostly 1+), 9 of 10 SSTs (7 with 5%-39% + cells, mostly 1+), 9 of 10 AGCTs (<5%-39%, four 1+, five 2+), 1 of 4 luteinized AGCTs (<5% and 1+), 8 of 9 JGCTs (mostly <5% to 39% and +1), 4 of 9 Sertoli cell tumors (either focal or >75% with variable intensity), 4 of 9 Sertoli-Leydig cell tumors (mostly <10% with variable staining), with the Leydig cells being positive in only 1 tumor (1+ and <5%), and 7 of 10 StCTs (4 tumors with more than 75% + cells, from 1+ to 3+). All fibromas, all but 1 fibrosarcoma (<5% and 1+), and all sex cord tumors with annular tubules were CD10 negative. CD10 expression was frequently seen in StCTs, SSTs, and thecomas of the ovary, although the latter 2 categories usually showed only faint immunoreactivity. In conclusion the frequency and intensity of CD10 immunoreactivity in pure stromal and sex cord-stromal ovarian tumors are low and contrast with the typical strong and diffuse immunostaining seen in endometrial stromal tumors; however, faint CD10 positivity is consistent with the diagnosis of ovarian SCST. Steroid cell tumors are often positive for CD10, but these tumors do not pose problems in differential diagnosis with endometrial stromal tumors. CD10 may play a useful role in aiding the differential between endometrial stromal tumors in the ovary and SCST and stromal tumors.

Ovarian spindle cell lesions: a review with emphasis on recent developments and differential diagnosis

Ovarian lesions composed of spindle cells comprise a heterogeneous group; most are neoplastic but several non-neoplastic conditions are also composed of spindle cells. This review discusses the main differential diagnoses of an ovarian spindle cell lesion, especially concentrating on the recent literature. The majority of ovarian spindle cell lesions fall into the broad category of fibromatous neoplasms whereas others in the sex cord-stromal group may also be composed of spindle cells, including thecomas, granulosa, and Sertoli-Leydig cell tumors and rarer neoplasms, such as sclerosing stromal tumor and signet-ring stromal tumor. In the recent past there have been several major contributions on various aspects of ovarian spindle cell lesions, including cellular and mitotically active cellular fibromatous lesions, smooth muscle neoplasms, and metastatic gastrointestinal stromal tumors. Other mesenchymal or epithelial tumors and mixed epithelial and mesenchymal neoplasms may also enter into the differential diagnosis of an ovarian spindle cell lesion. Several non-neoplastic lesions may be composed of spindle cells, including massive edema, ovarian fibromatosis, stromal hyperplasia, and stromal hyperthecosis. Morphology remains the mainstay in diagnosis but immunohistochemistry may be invaluable in certain circumstances, one example being the identification of a metastatic gastrointestinal stromal tumor within the ovary.

Gastrointestinal stromal tumors: diagnostic challenges and practical approach to differential diagnosis

Over the last decade, gastrointestinal stromal tumors (GISTs) have evolved from histogenetically obscure gastrointestinal mesenchymal tumors to well-defined tumors with distinctive clinical, morphologic, ultrastructural, histogenetic, and molecular characteristics, for which targeted therapy is available. This is largely attributable to the discovery of CD117 overexpression and activating mutations in c-kit or platelet-derived growth factor alpha genes in most of GISTs. The availability of specific diagnostic tests and targeted therapy for GISTs has led to an increased awareness of these tumors. At the same time, the list of potential GIST mimics has lengthened considerably and it has become increasingly important that GISTs be distinguished from their mimics because correct diagnosis has implications for both treatment and prognosis. The purpose of this review is to provide an update of the expanding differential diagnosis of GISTS, to draw attention to unusual GIST variants, to provide a practical approach the differential diagnosis of GISTs and to highlight some of the challenges faced by pathologists in resolving this differential diagnosis.

CD56 Is a Sensitive and Diagnostically Useful Immunohistochemical Marker of Ovarian Sex Cord-Stromal Tumors

Ovarian sex cord-stromal tumors comprise a heterogeneous group of neoplasms with wide morphological diversity, and they can be mistaken for a variety of other tumors. Some types, including granulosa and Sertoli cell tumor, may be confused with a neuroendocrine neoplasm. CD56 is a widely used neuroendocrine marker with a high sensitivity for neuroendocrine tumors and is commonly used as part of a panel to distinguish between a neuroendocrine neoplasm and other tumors in the differential diagnosis. In this study, we investigate CD56 staining in ovarian sex cord-stromal tumors. CD56 staining has not previously been studied in this group of neoplasms. We stained a large series of ovarian sex cord-stromal neoplasms (n = 85) with CD56. Neoplasms studied were adult granulosa cell tumor (n = 40), juvenile granulosa cell tumor (n = 8), Sertoli cell tumor (n = 1), Sertoli-Leydig cell tumor (n = 14), Leydig cell tumor (n = 2), steroid cell tumor, not otherwise specified (n = 2), sclerosing stromal tumor (n = 1), sex cord tumor with annular tubules (n = 2), and fibroma (n = 15). Three uterine tumors resembling ovarian sex cord tumor were also studied. Nonneoplastic ovaries, including 3 cases of pregnancy-related granulosa or Sertoli cell proliferation, were also included. In nontumorous ovaries, granulosa cells of follicular and corpus luteum cysts were consistently negative. The normal ovarian stroma was diffusely positive, as were the 3 pregnancy-related proliferations. All sex cord-stromal tumors except one were positive with CD56; staining ranged from focal to diffuse but was usually diffuse involving more than 50% of tumor cells. Staining was usually membranous with weaker cytoplasmic positivity. CD56 immunoreactivity is almost universal in ovarian sex cord-stromal tumors of all the major morphological types and is of no value in distinguishing a sex cord-stromal and a neuroendocrine neoplasm. Since CD56 is an extremely sensitive marker of ovarian sex cord-stromal tumors, it may be useful in the diagnosis of this group of neoplasms, especially in cases which are alpha inhibin or calretinin negative, and in distinguishing these from mimics which are CD56 negative.

Immunhistochemische Keimstrangmarker

Sex cord markers comprise proteins and hormones that are produced in sex cord-derivatives in normal ovaries and testes as well as in gonadal sex cord-stromal tumors. Sex cord markers (e.g. inhibin-alpha) are used clinically as serum tumor markers. Immunohistochemical staining of sex cord markers may be helpful in the differential diagnosis of ovarian sex cord-stromal tumors versus surface epithelial-stromal tumors, germ cell tumors, other ovarian tumors, and ovarian metastases. Inhibin-alpha has been shown to be the most specific marker of sex cord differentiation. In comparison, calretinin is a somewhat more sensitive albeit less specific marker. Currently, an immunohistochemical panel including inhibin-alpha and calretinin is considered most helpful in the differential diagnosis of ovarian sex cord-stromal tumors. CD99, Müllerian inhibiting substance (MIS), melan A and CD10, being sex cord markers of limited sensitivity and specificity, should only be used as part of an antibody panel in specific diagnostic settings. EMA, CK7 and chromogranin are considered additional markers that may be useful in the differential diagnosis of ovarian sex cord-stromal tumors.

Molecular characterization of sarcomatous change in a granulosa cell tumor

Sarcomatous transformation of a granulosa cell tumor (GCT) is a rare event. We describe the development of a rapidly progressive sarcomatous change in a woman who had initially presented with a classical GCT. A first recurrence occurred 23 months after the initial diagnosis when she was treated with external beam radiotherapy to her pelvis. A second recurrence 76 months following her initial surgery was consistent with a GCT. At 92 months, she presented with a further recurrence, outside of the radiotherapy field. This last recurrence had a different histologic appearance with features of sarcomatous change. Molecular analysis, using both reverse transcription-polymerase chain reaction and complementary DNA microarrays, has been used to analyze tissue obtained before and after the observed change in the tumor. The data show that GCT-specific genes, such as inhibin alpha, estrogen receptor, and follicle-stimulating hormone receptor, have been downregulated in the sarcomatous change. Significant upregulation of genes associated with an inflammatory response was also noted in the sarcoma, and this was consistent with the presence of a marked inflammatory infiltrate seen on histopathology. This study represents the novel application of microarray technology and demonstrates the unexpected finding of expression of the fibroblast activation protein gene in normal ovary. Although tumors such as this may be targets for the novel fibroblast activating protein-directed chemotherapeutic monoclonal antibody sibrotuzumab, the finding of expression in the normal ovary suggests the need for caution.

Immunohistochemical Evaluation of Canine Ovarian Tumors

Canine ovarian tumors (epithelial tumor, sex-cord stromal tumor, germ cell tumor) classifying into 9 histological types were examined immunohistochemically using placental alkaline phosphatase (PLAP), cytokeratin7 (CK7), desmin, S100, AE1/AE3, inhibin alpha, vimentin, and alfa feto-protein (AFP). The papillary and tubular types observed in epithelial tumors were immunoreactive for desmin and AE1/AE3. The papillary type was also immunoreactive for PLAP and CK7. The solid type, nest type, cord type, palisade type, cystic type and spindle type, which were observed in sex-cord stromal tumors, showed a positive immunoreaction for S100 but little or no positive immunoreaction for inhibin alpha with an exception of positive result in the palisade type. Most of the sex-cord stromal tumors were AE1/AE3-positive except for the palisade type. In the cobblestone type observed in germ cell tumors, only vimentin and AFP were positive. The present study elucidated the detailed histological and immunohistochemical characteristics of canine ovarian tumors.

Uterine tumour resembling ovarian sex cord tumour is an immunohistochemically polyphenotypic neoplasm which exhibits coexpression of epithelial, myoid and sex cord markers

AIMS

To describe the clinicopathological and immunohistochemical findings in four cases of uterine tumour resembling ovarian sex cord tumour (UTROSCT).

METHODS

Four UTROSCTs were stained with a wide range of antibodies, including epithelial (AE1/3, epithelial membrane antigen), myoid (desmin, alpha smooth muscle actin, h-caldesmon), sex cord (alpha inhibin, calretinin, melan A, CD99) and neuroendocrine (chromogranin, CD56) markers as well as hormone receptors (oestrogen receptor, progesterone receptor, androgen receptor), vimentin, CD10, WT1 and HMB45.

RESULTS

The tumours ranged from 0.8 to 19.5 cm. Three were relatively well circumscribed intramural myometrial lesions; the other was a pedunculated mass attached to the uterine serosa. The tumours were variably composed of solid, corded, trabecular, nested, glandular and retiform arrangements of tumour cells. In three cases, cells with eccentric nuclei and abundant eosinophilic cytoplasm, resulting in a rhabdoid appearance, were a prominent feature. Three cases were diffusely positive with AE1/3 and all with epithelial membrane antigen. Positivity with myoid markers was common with 3, 4 and 1 case respectively staining with desmin, alpha smooth muscle actin and h-caldesmon; 2, 4, 1 and 2 cases respectively were positive with alpha inhibin, calretinin, melan A and CD99. All were chromogranin negative and exhibited diffuse strong staining with CD56. All were diffusely positive with oestrogen receptor, progesterone receptor, vimentin and WT1. Three cases were androgen receptor positive and all were CD10 and HMB45 negative.

CONCLUSIONS

UTROSCT exhibits a polyphenotypic immunophenotype with coexpression of markers of epithelial, myoid and sex cord lineage as well as hormone receptors.

Immunohistochemical and functional biomarkers of value in female genital tract lesions

There has been a marked expansion in the literature pertaining to the use of immunohistochemical markers in female genital tract pathology, especially with regard to diagnosis. This review provides a survey of the antibodies commonly used in the diagnosis of gynecological lesions grouped as to function or type. Prognostic or predictive markers are also discussed where appropriate, although few of these are of value in everyday practice. It is stressed that when immunohistochemistry is used diagnostically, panels of markers provide better information than reliance on a single antibody.

Granulosa cell tumor arising in the wall of müllerian cyst of the broad ligament: report of a case and immunohistochemical study

CASE

A unique case of granulosa cell tumor arising in a müllerian cyst of the broad ligament in a 57-year-old woman is presented. The surgically resected unilocular cyst, measuring 9.5 x 9.5 x 6.5 cm3, situated within the right broad ligament. The inner surface of the cyst was lined by a single layer of ciliated columnar cells. Solid cell sheath of the spindled cells were demonstrated in this cystic wall. Immunohistochemically, these spindled cells were diffusely positive for cytokeratin 7, AE1/AE3, vimentin, smooth muscle actin, calretinin and weakly positive for inhibin, but negative for cytokeratin 20, epithelial membrane antigen and CD10.

CONCLUSION

Immunohistochemical findings suggested solid cell sheath surrounding the cyst was granulosa cell tumor. Granulosa cell tumor coexisted with müllerian cyst in the current case was recognized a unique histological feature.

Calretinin expression in tumors of adipose tissue

Although well established as a marker of mesothelial cells, calretinin is also expressed in several other tissue types, including adipose tissue. Accordingly, immunohistochemical staining for calretinin has been described in an increasing number of neoplasms other than mesothelioma. A detailed analysis of calretinin expression in lipogenic tumors has not yet been reported, however. Given the known expression patterns of calretinin in normal tissues, we predicted that calretinin immunoreactivity would be detected in lipoma and the various histologic subtypes of liposarcoma, and that this marker might be of use in the differential diagnosis of selected fatty tumors. A variety of pleomorphic and small round cell sarcomas were studied for comparison. Calretinin immunoreactivity was detected, at least focally, in all 10 samples of normal adipose tissue and in 22 of 23 lipomas or lipoma variants. Staining for calretinin was also positive within the lipogenic component of 28 of 29 liposarcoma variants. Of the 7 dedifferentiated liposarcomas, 3 were focally positive for calretinin. Pleomorphic variants of other sarcomas, including undifferentiated high-grade pleomorphic sarcoma, rhabdomyosarcoma, leiomyosarcoma, and malignant peripheral nerve sheath tumor also exhibited focal calretinin immunoreactivity in a minority of cases, as did some small round cell sarcomas. These results suggest that calretinin immunoreactivity in normal and neoplastic adipose tissue is more ubiquitous than previously reported and may be a useful, albeit nonspecific marker of lipogenic differentiation. However, its utility in the differential diagnosis of fatty tumors appears limited.

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.

Gastrointestinal stromal tumors metastatic to the ovary: a report of five cases

Five cases of gastrointestinal stromal tumor metastatic to the ovary are reported. The average patient age was 59 years (range, 44-81 years). The primary tumor was in the small bowel or its mesentery (4 cases) or stomach (1 case). The primary and metastatic tumors were discovered synchronously in 3 cases. In the other 2 cases, the ovarian tumors were discovered 18 months before a gastric tumor was identified and 27 years after a small bowel tumor had been resected. The ovarian tumors (three of which were bilateral) were usually solid, tan, and lobulated. Microscopically, three tumors had a pure spindle cell morphology, and two both spindle and epithelioid cell components. The diagnosis in all 5 cases was confirmed with positive c-kit (CD117) and negative desmin immunostaining. Variably positive immunoreactivity for either or both h-caldesmon and smooth muscle actin was seen in all 5 cases, and 3 cases were CD34-positive. Four patients died between 1 and 6.5 years (mean, 2.8 years) from the time of ovarian tumor diagnosis. The main differential diagnostic consideration was leiomyosarcoma; the most important features to help exclude this diagnosis were an absence of tumor in the uterus, low histologic grade, and a desmin-negative, c-kit-positive immunophenotype. Other differential considerations, including endometrial stromal sarcoma and fibrosarcoma, are discussed. Most of the ovarian tumors in this series were initially diagnosed as tumors of other types, a misdiagnosis with significant therapeutic and prognostic implications because of the specific therapy now available for gastrointestinal stromal tumors.

An immunohistochemical analysis of ovarian small cell carcinoma of hypercalcemic type

Ovarian small cell carcinoma of hypercalcemic type (OSCCHT) is a rare neoplasm with an aggressive behavior, broad differential diagnosis, and unknown histogenesis. To add to knowledge concerning the possible aid of immunohistochemistry in resolving problems in differential diagnosis and to further explore whether that modality points to any specific histogenesis, we undertook an immunohistochemical study of this neoplasm. Fifteen OSCCHTs (including four of the ''large cell" variant) were stained with a range of antibodies, some of which have not been investigated previously in this neoplasm. Cases were stained with AE1/3, EMA, BerEP4, CK5/6, calretinin, WT1, chromogranin, CD56, synaptophysin, CD99, NB84, desmin, S100, CD10, alpha inhibin, TTFI, and p53. Staining was classified as 0 (negative), 1+ (<5% cells positive), 2+ (5% to 25% cells positive), 3+ (26% to 50% cells positive), or 4+ (>50% cells positive). All cases were positive with p53 (two 1+, five 3+, eight 4+), 14 of 15 cases were positive with WT1 (one 1+, thirteen 4+), 14 of 15 with CD10 (three 1+, four 2+, two 3+, five 4+), 13 of 15 with EMA (three 1+, three 2+, two 3+, five 4+), 11 of 15 with calretinin (nine 1+, one 3+, one 4+), 9 of 15 with AE1/3 (eight 1+, one 2+), 4 of 15 with CD56 (one 1+, two 2+, one 4+), 3 of 15 with BerEP4 (two 2+, one 4+), 2 of 15 with synaptophysin (two 1+), and 1 of 15 with S100 (4+). All cases were negative with CK5/6, chromogranin, CD99, NB84, desmin, alpha inhibin, and TTF1. The only noticeable difference in the immunophenotype between typical OSCCHT and the large cell variant was that there was 4 +EMA positivity in three of four cases of large cell variant compared with two of 11 cases of typical OSCCHT. OSCCHT is characteristically positive with AE1/3, EMA, CD10, calretinin, WT1, and p53. Combined EMA and WT1 positivity, the latter usually intense and diffuse, may be of diagnostic value, inasmuch as only a few of the neoplasms in the differential diagnosis are positive with both antibodies. Negative staining with CD99, desmin, NB84, alpha-inhibin, and TTF1 may aid in the cases in which primitive neuroectodermal tumor, rhabdomyosarcoma, intraabdominal desmoplastic small round cell tumor, neuroblastoma, a sex cord-stromal tumor, and metastatic pulmonary small cell carcinoma are in the differential. Calretinin positivity precludes its use in the differential with granulosa cell tumors. The results of this investigation do not settle the issue of histogenesis, which remains enigmatic. The typical age distribution, follicle formation, and calretinin positivity are consistent with a sex cord origin. On the other hand, WT1 and EMA positivity and negative staining with alpha-inhibin would be unusual in a sex cord-stromal neoplasm and can be used as an argument for a surface epithelial origin. Germ cell and neuroendocrine origins seem highly unlikely.

Sertoli Cell Tumors of the Ovary

Ovarian Sertoli cell tumors are rare, and their morphologic spectrum, behavior, and factors influencing the latter are not clearly established. They may be mimicked by many different tumors, some of them more frequent than Sertoli cell tumors; immunohistochemistry may aid in this differential, but its role has not been analyzed in a large series. We studied the clinicopathologic features of 54 Sertoli cell tumors, including the immunohistochemical profile of 23 of them. The patients, 6 of whom had Peutz-Jeghers syndrome, ranged from 2 to 76 years of age (mean, 30 years). Eleven patients had estrogenic and 4 had androgenic manifestations. The tumors ranged from 0.8 to 30 cm, with the majority being in the range of 4 to 12 cm. They were all unilateral, usually solid, and often yellow. The predominant microscopic pattern was tubular, seen, albeit often only focally, in all tumors; other patterns were cords or trabeculae (28), diffuse (21), pseudopapillary (4), retiform (3), islands or alveolar arrangements (3), and spindled (3). The tubules were solid or hollow with the former being somewhat more common. Delicate septa were occasionally seen and were conspicuous in areas of one tumor. The stroma was abundant in 15 tumors with marked sclerosis in 4. The cells usually had pale to occasionally densely eosinophilic cytoplasm, but 6 tumors were composed of cells with prominent foamy cytoplasm, falling in the category of "lipid-rich" Sertoli cell tumor, and one had cells with clear non-foamy cytoplasm. Forty-four tumors were stage I (42 of them were stage Ia and 2 were stage Ic), 1 was stage II, 3 were stage III, and 6 were not adequately staged. Follow-up was available for 27 patients with stage I tumors, and all were alive and well at last follow-up except for 2 patients with stage Ia and 1 with stage Ic disease. Those 3 patients had pelvic-abdominal recurrences 18, 36, and 9 months, respectively, after the initial diagnosis. Two of the three clinically malignant stage I tumors had moderate to severe cytologic atypia and brisk mitotic activity (>5 or more mitoses/10 high power fields [HPFs]), and one of these had tumor cell necrosis. Among the 10 clinically benign stage I tumors with more than 5 years of follow-up, only 3 had >5 mitoses/10 HPFs, but none had more than mild cytologic atypia and none had tumor cell necrosis. Two of the three patients with stage III disease had follow-up information and one was alive at 16 months and the second developed splenic metastases 2 years after the initial diagnosis. Two of the three stage III tumors had at least moderate cytologic atypia and brisk mitotic activity. Immunohistochemical stains showed positivity for AE1/3-Cam5.2 in 15 of 23 tumors; Epithelial membrane antigen (EMA) was negative in all the tumors. Inhibin was positive in 18 of 22 tumors, calretinin in 10 of 20, CD99 in 19 of 22, vimentin in 17 of 18, smooth muscle actin in 4 of 18, neuron specific enolase in 8 of 16, S-100 in 2 of 20, and chromogranin was negative in all 21 cases studied. Although Sertoli cell tumors usually have a distinctive tubular pattern that facilitates the diagnosis, other patterns may occasionally predominate, causing confusion with various other primary and metastatic ovarian tumors. EMA, inhibin, and chromogranin represent the most helpful triad of immunomarkers serving to exclude two common mimics of Sertoli cell tumors (endometrioid carcinoma [inhibin-; EMA+; chromogranin-] and carcinoid tumor [inhibin-; EMA+; chromogranin+]). Although CD99 and calretinin are often expressed in these tumors, they are much less specific and not as helpful in the differential diagnosis. Most Sertoli cell tumors are stage I, unilateral, cytologically bland, and clinically benign, but occasional examples are high stage, and about 11% of stage I tumors have worrisome histologic features that may portend an adverse outcome. The tumors typically occur in young females, sometimes children who typically present with sexual precocity, and occasional patients have Peutz-Jeghers syndrome.

The utility of calretinin, inhibin, and WT1 immunohistochemical staining in the differential diagnosis of ovarian tumors

Calretinin has been proposed as a novel marker of ovarian sex cord-stromal tumors (SCST); this study aims to determine whether calretinin can complement or supplant the established utility of inhibin in the differential diagnosis of SCST. WT1 has been shown to be expressed in ovarian serous, but not mucinous neoplasms; its expression in a variety of ovarian tumors is also examined. Formalin-fixed, paraffin-embedded archival tissues from 111 primary ovarian tumors were analyzed with commercially available antibodies using semi-automated immunohistochemistry. Results were graded on a 4-tiered scale with staining of more than 0 but less than 5% of cells considered focal. Of 27 SCST, 56% were calretinin and 56% inhibin positive overall; 90% of granulosa cell tumors, 57% of Sertoli-Leydig cell tumors, 33% of thecomas, and 14% of fibromas were calretinin positive. Inhibin was expressed in 60% of granulosa cell tumors, 71% of Sertoli-Leydig cell tumors, 43% of fibromas, and 33% of thecomas. Of 35 surface epithelial tumors (SET), 8% of serous papillary tumors were calretinin positive, whereas 8% of serous papillary tumors and 13% of poorly differentiated carcinomas expressed inhibin. WT1 was expressed in 29% of all endometrioid carcinomas, 10% of borderline mucinous tumors, and no mucinous carcinomas; however, most of the other SETs were positive (77% serous papillary and 88% poorly differentiated carcinomas). Among the SCST, WT1 stained only granulosa cell tumors (75%), though often weakly or variably. Calretinin has only slightly greater sensitivity (76% versus 65%) and equal specificity to inhibin (92%) in the differential staining of granulosa or Sertoli-Leydig cell tumors, that is, nonstromal SCST. Hence, calretinin cannot replace but could complement inhibin as part of an immunohistochemical panel used for diagnostically challenging SCST. Although WT1 should be reliably positive in non-mucinous SET, staining of granulosa cell tumors and lack of expression in a sizable subset of endometrioid carcinomas may confound interpretation.