Signet-ring Stromal Tumor of the Ovary: Clinicopathologic Analysis and Comparison With Krukenberg Tumor

Sex Cord-Stromal Tumors of the Ovary: An Update and Review. Part I-Pure Ovarian Stromal Tumors

In two separate reviews, we reviews the time-honored but still frequently challenging features of ovarian sex cord-stromal tumors, and also emphasize new developments including unusual morphologic appearances that, despite the relative rarity of many of the tumors, result in a disproportionate number of differential diagnostic problems, variant immunohistochemical profiles, and specific molecular and syndromic associations. These neoplasms are also of historical interest as current knowledge is still based in significant part on the contributions of 2 giants of gynecologic pathology, Dr Robert Meyer and Dr Robert E. Scully. In part I, we present the major clinical, pathologic, and genomic features of the pure ovarian stromal tumors including comments on differential diagnosis and briefly note significant historical contributions. In part II we will discuss pure sex cord and sex cord-stromal tumors.

Relevance of Molecular Pathology for the Diagnosis of Sex Cord-Stromal Tumors of the Ovary: A Narrative Review

Ovarian sex cord-stromal tumors (SCSTs) account for 8% of all primary ovarian neo-plasms. Accurate diagnosis is crucial since each subtype has a specific prognostic and treatment. Apart from fibrosarcomas, stromal tumors are benign while sex cord tumors may recur, sometimes with a significant time to relapse. Although the diagnosis based on morphology is straightforward, in some cases the distinction between stromal tumors and sex cord tumors may be tricky. Indeed, the immunophenotype is usually nonspecific between stromal tumors and sex cord tumors. Therefore, molecular pathology plays an important role in the diagnosis of such entities, with pathognomonic or recurrent alterations, such as FOXL2 variants in adult granulosa cell tumors. In addition, these neoplasms may be associated with genetic syndromes, such as Peutz-Jeghers syndrome for sex cord tumors with annular tubules, and DICER1 syndrome for Sertoli-Leydig cell tumors (SLCTs), for which the pathologist may be in the front line of syndromic suspicion. Molecular pathology of SCST is also relevant for patient prognosis and management. For instance, the DICER1 variant is associated with moderately to poorly differentiated SLCTS and a poorer prognosis. The present review summarizes the histomolecular criteria useful for the diagnosis of SCST, using recent molecular data from the literature.

Update on Ovarian Sex Cord-Stromal Tumors

This article focuses on the recent advances in ovarian sex cord-stromal tumors, predominantly in the setting of their molecular underpinnings. The integration of genetic information with morphologic and immunohistochemical findings in this rare subset of tumors is of clinical significance from refining the diagnostic and prognostic stratifications to genetic counseling.

Ovarian Signet-ring Stromal Tumor: A Morphologic, Immunohistochemical, and Molecular Study of 7 Cases With Discussion of the Differential Diagnosis

Signet-ring stromal tumor (SRST) is a rare ovarian stromal neoplasm characterized by a population of bland signet-ring cells, devoid of mucin or lipid, in a generally cellular fibromatous stroma. Previous reports have described heterogenous immunohistochemical and molecular genetic findings, including occasional nuclear β-catenin expression and/or CTNNB1 mutations. We report 10 ovarian stromal neoplasms originally diagnosed as SRST. All but 1 tumor underwent detailed immunohistochemical analysis (including β-catenin) and 5 of 10 had CTNNB1 mutation analysis performed. All tumors contained a population of morphologically bland signet-ring cells that ranged from 15% to 95% of the neoplasm, characterized by a single large empty intracytoplasmic vacuole, mostly with nuclear indentation. Six of the 10 tumors contained cellular fibroma-like areas, comprising from 10% to 85% of the neoplasm. Three of the 10 tumors were reclassified as microcystic stromal tumor with signet-ring cells on the basis of the microcyst formation and hyalinized stroma, beta-catenin and cyclin D1 nuclear expression and/or CTNNB1 mutation, CD10 staining and largely absent expression of inhibin and calretinin. In the remaining 7 tumors, the diagnosis of SRST remained, constituting the largest series of SRST reported in the literature to date. The results of our study suggest that a subset of tumors diagnosed as ovarian SRST, especially those which show β-catenin nuclear positivity and/or CTNNB1 mutation, likely represent microcystic stromal tumor with variant morphology. We also suggest that at least a subset of SRSTs without evidence of Wnt/β-catenin pathway abnormalities may be related to ovarian fibromas. We discuss the differential diagnosis of ovarian neoplasms containing signet-ring cells.

Low-Grade Ovarian Stromal Tumors with Genetic Alterations of the Wnt/β-Catenin Pathway That Is Crucial in Ovarian Follicle Development and Regulation

The Wnt signaling pathway is important in the normal development and regulation of ovarian follicles throughout the lifecycle of females. Dysregulation of the Wnt signaling pathway, genetically or epigenetically, with subsequent activation of β-catenin has been implicated in tumorigenesis of a spectrum of ovarian neoplasms, from benign to malignant. We review the recent findings of the Wnt signaling pathway involved in regulating normal physiologic processes of the ovarian follicle cycle. We also review the β-catenin mutations in a family of low-grade ovarian stromal tumors, focusing on characterizing their shared morphological features and the utility of immunohistochemistry of β-catenin in facilitating the accurate diagnosis of these ovarian stromal tumors. The Wnt signaling pathway is one of the most critical mechanisms in regulating cell proliferation, differentiation, and morphogenesis. The Wnt signaling pathway comprises a diverse group of glycoproteins that serve as ligands and bind to transmembrane Frizzled family receptors. The ligand-receptor interactions activate the pathway and govern the downstream signaling cascades, ultimately affecting the transcriptional control of the cellular cytoskeleton, organelle dynamics, epithelial-mesenchymal interaction, and tissue remodeling in the ovary. Wnt signaling consists of two major pathways: a canonical pathway that is β-catenin-dependent and a non-canonical Wnt pathway that is β-catenin-independent. Canonical Wnt signaling is governed by the interaction of β-catenin with other molecules to regulate cellular decisions related to proliferation and differentiation. Recent studies have demonstrated that the Wnt signaling pathway plays important roles in the development and regulation of ovarian folliculogenesis and oogenesis.

Update on Ovarian Sex Cord-Stromal Tumors

This article focuses on the recent advances in ovarian sex cord-stromal tumors, predominantly in the setting of their molecular underpinnings. The integration of genetic information with morphologic and immunohistochemical findings in this rare subset of tumors is of clinical significance from refining the diagnostic and prognostic stratifications to genetic counseling.

Comprehensive review of imaging features of sex cord-stromal tumors of the ovary

Sex cord-stromal tumors of the ovary (SCST) are uncommon ovarian tumors arising from sex cord and/or stromal cells of the ovaries. They may be nonfunctional and asymptomatic or functional presenting with hyperestrogenic, hyperandrogenic or cushingoid symptoms. They present in a wide age group of women, mostly in early stages and follow a nonaggressive clinical course after surgical resection. They differ from more prevalent epithelial ovarian tumors which tend to present in older women in advanced stages with poor prognosis. Some of SCSTs are associated with clinical syndromes. We will review imaging features on ultrasound, computed tomography and magnetic resonance imaging, epidemiology and clinical presentations of these tumors.

An Epithelioid Smooth Muscle Neoplasm Mimicking a Signet Ring Cell Carcinoma in the Ovary

A 53-yr-old woman who presented with elevated renal indices was discovered to have a 4.5 cm right renal mass and an incidental 9.7 cm left ovarian mass on imaging studies. She underwent a partial nephrectomy and bilateral salpingo-oophorectomy, revealing a chromophobe renal cell carcinoma and an unusual ovarian neoplasm with epithelioid cells displaying prominent signet ring cell-like morphology. Immunohistochemical analysis of the ovarian neoplasm demonstrated that the tumor cells were diffusely immunoreactive for smooth muscle markers and negative for all tested cytokeratins and epithelial membrane antigen. On the basis of these results, the tumor was interpreted as an unusual epithelioid smooth muscle neoplasm with extensive signet ring cell-like features. Along with primary ovarian signet ring stromal tumors and sclerosing stromal tumors, this example adds epithelioid smooth muscle neoplasms with unusual cytologic alterations to the list of uncommon nonepithelial tumors that can simulate metastatic signet ring cell carcinoma (Krukenberg tumor) in the ovary.

Practical Review of Ovarian Sex Cord-Stromal Tumors

Ovarian sex cord-stromal tumors are uncommon tumors and clinically differ from epithelial tumors. They occur across a wide age range and patients often present with hormone-related symptoms. Most are associated with an indolent clinical course. Sex cord-stromal tumors are classified into 3 main categories: pure stromal tumors, pure sex cord tumors, and mixed sex cord-stromal tumors. The rarity, overlapping histomorphology and immunoprofile of various sex cord-stromal tumors often contributes to diagnostic difficulties. This article describes the various types of ovarian sex cord-stromal tumors and includes practical approaches to differential diagnoses and updates in classification.

Natural evolvement of lung tumors induced by N-ethyl-N-nitrosourea (ENU) and the impact of a high sucrose-high fat diet on tumor evolvement assessed by tumor histology in inbred BALB/c and C57BL/6J mice

Background

The model of lung tumors transplacentally induced by N-ethyl-N-nitrosourea (ENU) in inbred BALB/c and C57BL/6J mice was used to investigate the impact of a high sucrose-high fat (HSHF) diet on lung tumorigenesis.

Methods

The offspring was separated by gender and randomly divided into 2 subgroups in both ENU- and buffer-treated groups at the time of weaning. One subgroup was put on the standard diet and the other on the HSHF diet from weaning to the age of 24 weeks. The entire lungs went through a standard process of paraffin-embedded blocks. Every lung block was cut in serial sections but one in every five sections was saved to generate step sections that were stained by hematoxylin and eosin. The tumor histology was assessed on the step sections.

Results

At 24-week checkpoint, a spectrum of histological changes was observed in the mice on both diets. Specifically, they presented as alveolar hyperplasia, adenomas and adenomas with nuclear dysplasia at various degrees. Those tumors were actually at different developmental stages. Lung adenocarcinomas were developed in mice on the HSHF diet. A cluster of tumor cells with wide foamy or clear or signet-ring shaped cytoplasm (fatty changes) appeared in a low frequency on the HSHF diet.

Conclusions

The observed histological changes indicated that lung tumors were developed at different times and evolved at different paces. The HSHF diet accelerated the course of tumor evolvement. Tumor cells with fatty changes might be induced by the HSHF diet.

Ovarian Sex Cord-Stromal Tumors: Reflections on a 40-Year Experience With a Fascinating Group of Tumors, Including Comments on the Seminal Observations of Robert E. Scully, MD

CONTEXT.—

This year being the 60th anniversary of the publication of the excellent book Endocrine Pathology of the Ovary by John McLean Morris, MD, and Robert E. Scully, MD, the writer reflects on that work and in particular the remarkable contributions of its second author to our knowledge in this area.

OBJECTIVE.—

To review ovarian sex cord-stromal tumors.

DATA SOURCES.—

Literature and personal experience.

CONCLUSIONS.—

The essay begins with remarks on the oftentimes straightforward stromal tumors of the ovary because the commonest of them, the fibroma, dominates from the viewpoint of case numbers. Then, the sclerosing stromal tumor and the peculiar so-called luteinized thecomas of the type associated with sclerosing peritonitis are discussed in greater detail and their wide spectrum is illustrated. Brief mention is made of 2 rare neoplasms: the ovarian myxoma and signet-ring stromal tumor. Discussion then turns to the more recently recognized intriguing tumor tentatively designated microcystic stromal tumor and the commonest malignant tumor in this entire family, the so-called adult granulosa cell tumor, which despite its name may occasionally be seen in young individuals. The second variant of granulosa cell tumor-that which usually, but not always, occurs in the young-the so-called juvenile granulosa cell tumor, is then discussed. In the section of Sertoli-Leydig cell tumors, particular attention is focused on unusual tumors with heterologous elements and the remarkable so-called retiform tumors, which have a predilection for the young, often have distinctive gross features, and exhibit slitlike spaces and papillae. The essay concludes with consideration of the sex cord tumor with annular tubules.

Bilateral Signet-ring Stromal Tumor of the Ovary: A Case Report With Next-generation Sequencing Analysis and FOXL2 Mutation Testing

Signet-ring stromal tumor (SRST) is a rare benign stromal neoplasm of the ovary with only a handful of cases reported in the literature. To date, all but one reported cases have been unilateral, and the pathogenesis and underlying genetic abnormalities of this entity are not well characterized. Here we report a case of a 70-yr-old woman with bilateral ovarian SRST, clinically presenting with abdominal distention and rectal bleeding, and bilateral ovarian masses on imaging studies. Total hysterectomy and bilateral salpingo-oophorectomy were performed, revealing bilateral solid ovarian tumors with characteristic signet-ring cell morphology. The immunohistochemical profile-positive steroidogenic factor 1, calretinin, and smooth muscle actin, and negative epithelial membrane antigen-supported the diagnosis of SRST. CTNNB1 mutation and abnormal nuclear beta-catenin expression have recently been reported in 2 SRSTs. However, we did not identify any mutations in 54 oncogenes and tumor suppressor genes (including CTNNB1) by next-generation sequencing analysis, and PCR Sanger sequencing did not reveal FOXL2 C134W mutation, suggesting the possibility of heterogenous pathogenesis of these tumors.

Signet Ring Stromal Cell Tumor: A Legitimate (Benign) Mimic of Krukenberg Tumor

Signet ring stromal cell tumor is a rare, benign ovarian neoplasm thought to arise from ovarian stromal cells. The pathophysiology of these tumors is poorly understood. They present in women in a wide age range, often with nonspecific symptoms including lower abdominal or pelvic pain. Their morphologic appearance raises a critical differential diagnosis of Krukenberg tumor, an aggressive malignancy with significant implications for patient management. For this reason, it is important for the pathologist to be aware of signet ring stromal cell tumor and its differentiating features, including useful histochemical and immunohistochemical ancillary tests. These tumors are curable with surgical excision, and there have been no recurrences or metastases among reported cases.

Oncogenic Activation of the Wnt/β-Catenin Signaling Pathway in Signet Ring Stromal Cell Tumor of the Ovary

Signet ring stromal cell tumor (SRSCT) of the ovary is a very rare benign ovarian neoplasm. To date, no underlying genetic mechanism has been identified. In this study, 50 oncogenes and tumor suppressor genes were evaluated for mutations in a typical SRSCT using the next-generation DNA sequencing approach. An in-frame deletion of 30 nucleotides in the glycogen serine kinase-3 beta phosphorylation region of the β-catenin gene (CTNNB1) was identified, and the finding was confirmed by Sanger sequencing. This deletion (c.68_97del) at the protein level would lead to a p.Ser23_Ser33delinsThr oncogenic-type mutation. Subsequent immunohistochemistry showed prominent nuclear accumulation of β-catenin and cyclin D1 in tumor cells. Thus, mutational activation of the Wnt/β-catenin pathway could be a crucial event in the molecular pathogenesis of SRSCT of the ovary. These findings may also assist in the diagnosis of this rare tumor.

An Unusual Evolution of Krukenberg Tumour: A Case Report

Krukenberg tumours are rare metastatic tumours of the ovaries characterized by the presence of mucin-producing neoplastic Signet Ring Cell Carcinoma (SRCC). At first glance, this tumour may be confused with a primary ovarian tumour. Surgery and chemotherapy combination have led to improvement in prognosis, but it still remains severe. We report the case of a 60-year-old woman with a Krukenberg tumour rising from a low differentiated gastric adenocarcinoma. The patient was clinically stable for 26 months after surgery until she experienced a prompt decline and died of cerebral haemorrhage within two weeks. The aim of this article was to give an overview of the Krukenberg tumour starting from our case report and comparing it with clinicopathological characteristics of this pathology derived from a review of recent literature.

Perspectives on signet ring stromal cell tumor and related signet ring cell lesions of the gonads

In this article, we discuss advances in our knowledge of the pathology of signet ring stromal cell tumor and related signet ring cell lesions of the ovary and a single case of signet ring stromal cell tumor of the testis. We divide ovarian signet ring cell lesions into 3 categories that reflect differences in their pathogenesis and histologic appearance. With 1 exception, all authentic cases of signet ring stromal cell tumor have been unilateral. Cases of ovarian signet ring stromal cell tumor from the literature can arise in 2 ways. The majority of cases arise multifocally from fibroma, whereas the remainder likely arise directly from the ovarian stroma. In difficult cases, immunocytochemistry provides improved diagnostic accuracy in distinguishing signet ring stromal cell tumor and its mimics from Krukenberg tumor. The most useful antibodies in this regard are epithelial membrane antigen and vimentin.

Dyspnoea and the ovaries: a rare presentation of Krukenberg tumour

Krukenberg tumour is a metastatic signet-ring adenocarcinoma of the ovary, usually with a gastrointestinal primary detected metachronously or synchronously. We present here a case of a 48 year-old woman who presented with a prolonged history of dyspnoea on exertion. Workup had revealed a pelvic mass. Thoracocentesis of her pleural effusion, with cytology, and pathology reports from her total abdominal hysterectomy with bilateral salpingo-oophorectomy revealed a carcinoma with signet-ring cells. Immunostains were positive for CDX2, CK7 and CK20, which was highly suggestive of a gastric primary. Colonoscopy was negative, and an oesophagogastroduodenoscopy revealed a few small crater ulcers, the biopsy of which was negative for cancer. A right-sided pleurodesis was performed for the unremitting malignant effusion, and a PleurX catheter was placed in her left pleural space. She was discharged home with a very poor prognosis.

WT1 expression in the female genital tract

The Wilms tumor gene 1 (WT1) has been reported in normal tissues and many neoplasms of the female genital tract. This review discusses WT1 expression in the female genital tract and its potential utility in the differential diagnosis of neoplasms that occur at this location. WT1 is of value in the differential diagnosis of synchronous serous carcinomas arising in the ovary/fallopian tube/peritoneum and endometrium, as strong WT1 positivity in both tumors points toward an extrauterine origin. In addition, WT1 can be used to distinguish sex cord stromal tumors (WT1 positive) from endometrioid carcinomas (OECs). WT1 expression is not helpful in the differential diagnosis of ovarian serous carcinomas (OSCs) and transitional carcinomas, as both are typically positive and has limited value in the distinction of serous tumors arising in the ovary/fallopian tube/peritoneum from mesotheliomas. WT1 is also not helpful to differentiate small cell carcinoma of hypercalcemic type from juvenile granulosa cell tumor, a common diagnostic problem. Intra-abdominal desmoplastic round cell tumor reacts to WT1 (C-terminal) in contrast to all other tumors discussed which helps to separate this rare tumor from most other small round cell tumors that may involve, primarily or secondarily, the ovary with the exception of small cell carcinoma of hypercalcemic type that typically reacts with the N-terminal of WT1.

Metastatic Neoplasms Involving the Ovary

In this review, ovarian metastatic carcinomas from various sites, as well as other neoplasms secondarily involving the ovary, are discussed. As well as describing the morphology, the value of immunohistochemistry in distinguishing between primary and metastatic neoplasms in the ovary is discussed. While immunohistochemistry has a valuable role to play and is paramount in some cases, the results should be interpreted with caution and with regard to the clinical picture and gross and microscopic pathologic findings.

Nonserous Ovarian Epithelial Tumors

This review covers the group of relatively uncommon nonserous ovarian epithelial tumors. The authors focus on the group's distinctiveness from the much more common serous tumors and show the similarities across entities. Diagnostic criteria that separate the different entities are currently being debated. Particular problems include the reproducible diagnosis of high-grade endometrioid, transitional cell, mixed epithelial and undifferentiated carcinomas. Furthermore, despite recognition that most malignant mucinous tumors involving ovary represent metastases from extraovarian primary sites, many misdiagnoses still occur. The authors discuss their rationale behind their opinions about these problematic topics.

Signet-ring stromal tumor of the ovary: an extremely rare neoplasm

Signet-ring stromal tumor (SRST) of the ovary is an extremely rare neoplasm. Herein, we present a SRST of the ovary, which is the twelfth report in the literature. A 44 year-old, G4P2 patient was admitted with the complaint of polymenorrhea. She was operated on for persistent semisolid ovarian mass measuring 5 cm in diameter. The pathological examination confirmed the diagnosis of a benign ovarian SRST. In conclusion, SRST is an extremely rare benign ovarian tumor with good prognosis according to the current literature. Although the recurrence rate or malignant transformation potential of these tumors are not yet known, close follow-up in the post-operative period may be beneficial.

Primary signet ring cell mucinous ovarian carcinoma: a case report and literature review

A 24-year-old female patient presented with an extremely rare primary signet cell carcinoma of the right ovary 1 year after surgery for a mucinous borderline tumour of the left ovary. Relaparotomy was carried out with right adnexectomy, appendectomy and partial omentectomy. Surgery was followed by 6 courses of paclitaxel/carboplatinum chemotherapy. After an initial response, the patient again developed increasing ascites. The patient was transferred to our hospital and a re-relaparotomy was carried out, completing the operation. After 3 courses of pegylated doxorubicin/trabectedin, the clinical course showed a positive response and a decline of the tumour marker CEA in peripheral blood. After 5 months, ascites developed in the retroperitoneum so that the chemotherapy had to be changed. In spite of a positive response with the new chemotherapy, the patient died of a very rare pulmonary complication after 1 month within 2 days.

Ovarian Signet-Ring Stromal Tumor: A Potential Diagnostic Pitfall

Signet-ring stromal tumor is a rare ovarian neoplasm with only 10 reported cases in the literature. We report an unusual case of ovarian signet-ring stromal tumor in a 69-year-old woman who presented with right adnexal mass and underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. The diagnosis was based on histological, histochemical, immunohistochemical, and electron microscopy characteristics. The main significance is to differentiate this benign tumor from the highly malignant Krukenberg tumor, and this differential diagnosis is discussed.

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.

Primary Ovarian Adenofibromatous Neoplasms With Mucin-Containing Signet-ring Cells

The presence of mucin-containing signet-ring cells in an ovarian neoplasm is considered strong evidence for a metastatic rather than primary tumor. The clinicopathologic features of 2 ovarian adenofibromatous neoplasms with mucin-containing signet-ring cells (AFN-SRs), proven by the long-term follow-up of 10 and 15 years to be primary tumors, are presented as exceptions to this general guideline. Both of these tumors were initially strongly favored to be metastatic adenocarcinoma by expert consultants in gynecologic pathology, which underscores the diagnostic difficulty that these rare and unusual neoplasms can pose. Although long-term follow-up of AFN-SRs is still necessary to exclude the possibility of metastases, the following constellation of features can correctly suggest a primary neoplasm rather than a Krukenberg-like metastatic process at the time of presentation: (i) the appearance of fibromatous stroma as an integral part, as opposed to reactive part, of the neoplasm, (ii) a semiorganized rather than completely haphazard pattern to the placement of the epithelial elements, with a circumscribed noninfiltrative interface with ovarian parenchyma, (iii) the absence of angiolymphatic invasion, (iv) tumor unilaterality, and (v) the lack of a known primary source. The virtual absence of literature on these low-grade malignancies, coupled with the occurrence of 2 such tumors within a 7-year period at a single community hospital, suggests that many AFN-SRs continue to be misdiagnosed as metastatic adenocarcinoma.

[Differential diagnosis of ovarian metastases]

Ovarian metastases comprise 7-10% of all malignant ovarian tumors. The detection of ovarian metastases is difficult because primary ovarian tumors are a morphologically very heterogeneous group, and metastases can simulate an primary ovarian tumor perfectly. A correct diagnosis, however, is most important in order to avoid an unnecessary and ineffective chemotherapy. Therefore, every morphologically unusual ovarian tumor should raise doubts. In addition, mucinous and endometrioid tumors may also be metastatic in nature. Immunohistochemistry, as well as knowledge on the patient's history, will clarify most of the suspicious cases.

Oxyphilic Adenomatoid Tumor of the Ovary

We describe an unusual example of ovarian adenomatoid tumor that was an incidental finding in the ovary of a 52-year-old woman and was characterized by cells with abundant eosinophilic cytoplasm, an occasional feature of the adenomatoid tumor but one that, in an ovarian example, may cause added diagnostic confusion to that already engendered by the rarity of this neoplasm in the ovary. The typical numerous small vacuoles of the neoplasm sometimes had the appearance of signet ring cells. These 2 features (oxyphil and signet ring cells) caused a broad differential. Tumor cells were positive with broad-spectrum cytokeratins as well as mesothelial markers CK5/6, WT1, and calretinin. In reporting this case, we focus on the differential diagnosis of ovarian neoplasms and tumorlike conditions with vacuoles and related spaces, a topic that embraces many diverse entities.

An in-depth look at Krukenberg tumor: an overview

Krukenberg tumor is an uncommon metastatic tumor of the ovary. This article provides an overview of the major pathologic manifestations of Krukenberg tumor, patient characteristics, clinical and laboratory features of the disease, prognostic factors, and current knowledge about its pathogenesis. Pathologists have to be familiar with the diagnostic histopathologic features of the tumor and its principal differential diagnoses. Awareness of the diagnostic manifestations of the tumor leads to the correct diagnosis and prevents tumor misclassification, thus avoiding improper clinical management. The article also addresses the potential clinical utility of serum CA 125 in patients with Krukenberg tumors. Prognosis of Krukenberg tumor is still very poor but our review of the literature reveals several factors that appear to have an impact on survival. There is no established treatment for Krukenberg tumors. A national registry and prospective studies are needed to set a therapeutic approach for Krukenberg tumors in the hope of improving the survival rate.

Metastatic neoplasms involving the ovary: a review with an emphasis on morphological and immunohistochemical features

The ovary is a common site of metastatic tumour. In many cases of ovarian metastasis there is a known history of malignancy but in other cases the ovarian tumour is the first manifestation of disease. In this review metastatic colorectal, appendiceal, gastric, breast, pancreatic and biliary tract, hepatocellular, renal, transitional and cervical carcinomas and metastatic malignant melanoma involving the ovary are discussed, as is the issue of synchronous ovarian and endometrial carcinomas. Peritoneal tumours, including primary peritoneal carcinoma, mesothelioma and intra-abdominal desmoplastic small round cell tumour, involving the ovary are also discussed, together with a variety of other rare, metastatic ovarian neoplasms. Many metastatic adenocarcinomas involving the ovary, especially those exhibiting mucinous differentiation, closely mimic primary ovarian adenocarcinomas with morphologically bland areas simulating benign and borderline cystadenoma. This is referred to as a maturation phenomenon. In recent years immunohistochemistry, especially but not exclusively differential cytokeratin (CK7 and CK20) staining, has been widely used as an aid to distinguish between a primary and secondary ovarian adenocarcinoma. While immunohistochemistry undoubtedly has a valuable role to play and is paramount in diagnosis in some cases, the results must be interepreted with caution, especially in mucinous tumours, and within the relevant clinical context. We feel the significance of differential cytokeratin staining is not always understood by histopathologists and this can result in erroneous interpretation. We critically discuss the value of immunohistochemistry and associated pitfalls with each tumour type described.

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.

Primary signet-ring stromal tumor of the testis

We present, in a 47-year-old man, the first case of the signet-ring stromal tumor of the testis. The tumor was located beneath the tunica albuginea surrounded by the testicular tubules and rete testis. It was sharply circumscribed by a thin and irregular fibrous capsule. Histologically, it was composed of cells with a widespread signet-ring cell change separated by fibrous stroma. In some places, the signet-ring cells formed vague Indian files, thus resembling metastatic carcinomas with signet-ring cell morphology. Under high magnification, most of the cytoplasm of the tumor cells was seen to be replaced by an empty clear vacuole which pushed the nuclei to the periphery of the cells. Some of the nuclei were indented by the cytoplasmic vacuoles, others were without indentation. Only in a small area did the tumor show cells without a signet-ring cell change. They looked like epithelioid fibroblasts forming abortive and vaguely tubular structures. Mitoses and necroses were absent. Mucicarmine and PAS stains were negative. Immunohistochemically, the tumor was vimentin positive and it was negative with antibodies to cytokeratins, inhibin, prostatic acid phosphatase, prostate-specific antigen, smooth muscle actin, S-100 protein, EMA and calretinin. The signet-ring stromal tumor of the testis is thus similar morphologically and immunohistochemically to the signet-ring stromal tumor of the ovary. The patient was free of recurrence and metastasis 3 years after the excision.