Microcystic Stromal Tumor of the Ovary: Report of 16 Cases of a Hitherto Uncharacterized Distinctive Ovarian Neoplasm

Ovarian Sex Cord-Stromal Neoplasms: An Overview of Molecular Events and How to Correlate Morphology With Molecular Findings

Since the discovery in 2009 that missence pathogenic variants/mutations in FOXL2 are extremely common in ovarian adult granulosa cell tumours, the last 2 decades have witnessed significant developments in our understanding of the molecular events underlying the pathogenesis of other ovarian sex cord-stromal tumours (SCSTs). In this review, we cover the molecular events in ovarian SCSTs and provide practical guidance to the reporting pathologist as to how and when molecular testing may be useful in diagnosis. We stress the need to correlate the morphology and molecular since most of the molecular events are not entirely specific for a particular tumour type and our knowledge is continually evolving with the elucidation of "new" molecular events. We also discuss that in some tumours, molecular testing is helpful in triaging the patient for genetic referral and germline testing since some of the molecular events may be germline in nature.

Ovarian Microcystic Stromal Tumor with Significant Nestin Expression: A Unique Case

Ovary microcystic stromal tumor (MCST) is an extremely rare subtype of sex cord-stromal neoplasm, and only 57 cases have been reported. We herein report a unique case of ovarian MCST with positive nestin expression in a 39-year-old Chinese woman. The tumor showed microcystic stromal histological structures and characteristically expressed the CD10, WT-1, and Ki67 proteins. A molecular analysis identified a point mutation (c.110C > T) in exon 3 of the CTNNB1 gene. To our knowledge, no report has described a case of ovarian MCST with positive staining for nestin protein. Our study provides new insights into the tumor biology of ovarian MCST.

Huge Ovarian Microcystic Stromal Tumor Presenting As Acute Abdomen in a Patient With Familial Adenomatous Polyposis: A Case Report With Magnetic Resonance Imaging Findings

Microcystic stromal tumors (MCST) are rare sex cord-stromal tumors with distinctive microcystic features and stromal tumor immunophenotypes. Few reports have discussed MCST from the perspective of magnetic resonance imaging (MRI). In this report, we describe the MRI findings of MCST, review our case, and discuss it based on previous reports. A 24-year-old female with a history of familial adenomatous polyposis (FAP) presented to the emergency department with complaints of lower abdominal pain. A plain abdominal computed tomography scan revealed a huge ovarian tumor measuring 19 cm. MRI revealed an isointense ovarian tumor on T1-weighted images and a heterogeneous high signal intensity on T2-weighted images. Contrast-enhanced MRI demonstrated enhancement confined to the capsular structures. Based on the tumor size and MRI findings, malignancy could not be definitively excluded. However, considering the clinical presentation, a diagnosis of tumor infection was made, and an open adnexectomy was subsequently performed. Pathological examination confirmed the diagnosis of MCST, and the patient's condition progressed without apparent recurrence one year after surgery. In previous reports, MCST has been associated with FAP, and almost all cases were benign. Patients diagnosed with FAP can reduce the risk of acute abdominal pain by using less invasive treatments, as long as they keep up with regular checkups and screenings.

A case report on the microcystic stromal tumor of the ovary: A rare type of ovarian tumor

A microcystic stromal tumor (MCST) is considered a benign tumor. However, reported cases of recurrence and metastases indicate that it has got malignant features. Its recurrence is strongly linked to undertreatment.

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

In two separate reviews, we review 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.

Ovarian Microcystic Stromal Tumor With Intraovarian Recurrence and Peritoneal and Omental Spread: A Case Report With Morphological, Immunohistochemical, and Molecular Analysis

Microcystic stromal tumors (MCSTs) are rare ovarian stromal tumors. They harbor CTNNB1 or APC mutations, resulting in β-catenin nuclear expression. To date, all MCST cases treated with oophorectomy or more extensive surgery have followed benign clinical courses. However, 1 of the 3 cases treated with ovarian cystectomy/tumor resection recurred in the residual ovary and iliac fossa 9 years after ovarian cystectomy. Here, we report a case of recurrent MCST in a 38-year-old woman. The patient underwent ovarian cystectomy for a 7.5 cm solid-cystic right ovarian mass, which showed classic morphological and immunophenotypical features of MCST. Four years later, the tumor recurred in the residual right ovary as a 21 cm mass, involving the pelvic peritoneum and omentum. Molecular analysis using next-generation sequencing revealed a single C TNNB1 exon 3 S37A mutation in the recurrent tumor. To the best of our knowledge, this is the second case of recurrent MCST, which presents more evidence that MCST has the potential to recur and spread locally. Rather than ovarian cystectomy/tumor resection, more aggressive surgery, such as unilateral oophorectomy, may be necessary to decrease the risk of recurrence. Long-term postsurgery follow up is needed, especially after simple ovarian cystectomy/tumor resection.

Primary sclerosing liposarcoma of the ovary: Case report and a review of the literature

INTRODUCTION

Primary soft tissue sarcoma of the ovary is uncommon, with most literature reports being in the format of a single case report or small case series.

PRESENTATION OF CASE

We report a case of a primary sclerosing liposarcoma of the ovary in a 67-year-old lady. She presented with a rapidly growing ovarian mass, which was surgically excised. Histologically, the lesion appeared nodular with alternating hypercellular and low-cellularity areas, with areas of necrosis. It comprised atypical spindled, oval and stellate cells set in abundant myxoid and fibrous hyalinised stroma. Immunohistochemistry showed expression of p16, CDK4, CD34, S-100 and MDM2. The case was sent to a referral centre where MDM2 gene amplification was detected by interphase fluorescent in-situ hybridisation (FISH) analysis, rendering a diagnosis of well-differentiated sclerosing liposarcoma with focal low-grade dedifferentiation.

DISCUSSION

To the best of our knowledge, this is the first reported example of a sclerosing variant of liposarcoma in the ovary. Differential diagnosis includes microcystic stromal tumour (MST), sclerosing stromal tumour (SST), atypical spindle cell lipoma, myxoid liposarcoma, myxofibosarcoma, solitary fibrous tumour and low grade fibromyxoid sarcoma.

CONCLUSION

Ovarian sarcomas are characterised by a rapid and aggressive clinical course, requiring multidisciplinary team input for ongoing management. Complete surgical resection with clear margins is the mainstay of treatment.

TFE3 nuclear expression as a novel biomarker of ovarian sclerosing stromal tumors and associated with its histological morphology

Sclerosing stromal tumors of the ovary are benign and tend to occur in youthful women with lobular structures at low frequencies. Three types of cells, including luteinized cells, short spindle myoid cells, and intermediate cells, are found in the lobules which abundant in the blood vessels. Currently, immunohistochemistry is used to detect normal follicles, sclerosing stromal tumors, granulosa cell tumors, and fibromas/thecomas. Our research results showed that transcription factor enhancer 3 (TFE3) was moderate to strong positive in the theca interna layer of normal follicles. TFE3 was expressed in seven out of eight sclerosing stromal tumors, mainly in luteinized cells. It did not express in 20 granulosa cell tumors. Of the nine fibromas/thecomas, TFE3 was weakly staining in 2 cases and negative in the remaining 7 cases. The expression of TFE3 was also weak in only one microcystic stromal tumor. 8 cases of sclerosing stromal tumors were analyzed by FISH using a TFE3 separation probe, and the results were negative. In short, as a nuclear transcription protein, TFE3 specifically expressed in sclerosing stromal tumors and could serve as a new marker for the diagnosis and differential diagnosis of sclerosing stromal tumors. Moreover, we speculate that TFE3 will promotes the formation of the vascular plexus after entry into the nucleus, which can further explain why sclerosing stromal tumors are different from other ovary sex-cord stromal tumors.

Sclerosis in Sex Cord-Stromal Tumors Other Than the Sclerosing Stromal Tumor: A Report of 70 Cases

Sclerosis is well-known in sclerosing stromal tumors (SSTs), as its name indicates, but has not been evaluated in other ovarian sex cord-stromal tumors (SCSTs). Its presence in other SCSTs has sporadically caused diagnostic problems in cases we have seen, and this prompted us to review SCSTs with appreciable sclerosis; tumors containing at least 20% sclerosis were included. Seventy cases were identified: 20 thecomas, 20 juvenile granulosa cell tumors (JGCTs), 8 adult granulosa cell tumors (AGCTs), 5 sex cord tumors with annular tubules, 6 retiform Sertoli-Leydig cell tumors (SLCTs; all of the intermediate differentiation), 4 nonretiform SLCTs (3 well-differentiated, 1 of intermediate differentiation with heterologous elements), 4 Sertoli cell tumors, and 3 microcystic stromal tumors (MSTs). Paucicellular sclerotic zones comprised 20% to 95% of the tumors and when conspicuous often obscured diagnostic features. Thirty-one tumors (10 thecomas, 19 JGCTs, 1 AGCT, and 1 MST) showed sclerotic zones focally enveloping nodules of tumor cells, imparting a pseudolobular appearance, and sclerosis often occurred within lobules as well. Ten of these (5 thecomas and 5 JGCTs) also had prominent staghorn blood vessels, generating a low-power appearance focally similar to SST. In 17 tumors, the sclerosis resulted in "compression" of the tumor cells into cords and/or solid tubules. Correct diagnosis in these cases is dependent on careful examination of the cellular zones of the neoplasms, but awareness of the extent of sclerosis that may be seen in diverse SCSTs may be crucial in suggesting the correct diagnosis particularly when the material is limited as in the intraoperative setting. Our findings highlight for the first time the occurrence and character of sclerosis in sex cord tumors other than SSTs and fibromas. Sclerosis is seen in descending proportion of the tumor types as follows: retiform SLCTs, thecomas, MSTs, JGCTs, sex cord tumors with annular tubules, Sertoli cell tumors, AGCTs, and nonretiform SLCTs. Its character can vary somewhat, having particular features in the sex cord tumor with annular tubules (hyaline material within tubules often coalescing and extending beyond the nests to form confluent aggregates) and retiform SLCTs (common in papillary cores).

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.

Microcystic Stromal Tumor with Predominant Bizarre Nuclei of Ovary in a Pregnant Woman

Microcystic stromal tumor (MST) is a rare type of pure stromal tumor in the category of ovarian sex cord-stromal tumors. It is characterized by a distinctive microcystic appearance with bland tumor cells. Although the pathological diagnosis can be straightforward based on the typical histomorphology in most MSTs, the cases with morphologic variation can pose a diagnostic challenge due to unfamiliarity of pathologists with the histologic spectrum of MST and its negativity for inhibin and calretinin, the commonly used sex cord-stromal markers. The coexistence between MST and mucinous epithelial tumor is extremely rare. We present the first case, to our knowledge, of ovarian MST with predominant bizarre nuclei coexisting with mucinous cystadenoma in a pregnant woman. The histomorphology in this case presents a diagnostic challenge and raises differential diagnosis for a wide variety of ovarian malignant neoplasms including nonneoplastic lesions.

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.

A Constellation of Rare Gynecological Malignancies and Familial Adenomatous Polyposis Gastrointestinal Adenocarcinoma: A Case Report

Ovarian microcystic stromal tumors (MST) are a rare subtype of sex-cord stromal tumors. We are presenting a case of a MST arising in a patient with familial adenomatous polyposis (FAP) and concurrent colonic adenocarcinoma. During the patient's workup of an ampullary adenoma associated with her FAP, she was found to have an enlarged uterus with a thickened endometrium and an incidental pelvic mass on the fundus of the uterus. Subsequent imaging identified heterogenous bulky ovaries. This patient underwent surgical resection including a total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, bilateral pelvic sentinel lymph node biopsy during her planned total proctocolectomy and transduodenal ampullectomy. Extensive histologic and immunohistochemical investigations were completed and the final pathology report revealed a unique compilation of International Federation of Gynecology and Obstetrics Stage II, grade 1 endometrioid endometrial adenocarcinoma, bilateral ovarian MST, a sperate pedunculated mass favoring a diagnosis of uterine tumor resembling ovarian sex cord tumor (UTROSCT), 2 distinct adenocarcinomas of the colon (T2N0 and T1N0) and a tubular adenoma of the ampulla. The pathology showed the endometroid adenocarcinoma was β-catenin negative while the MST and UTROSCT both showed nuclear positivity with β-catenin. To our knowledge this is the first reported case of a UTROSCT with concurrent endometrial adenocarcinoma presenting with bilateral ovarian MST's and adenomatous polyposis coli gene positive FAP colon adenocarcinoma.

Anastomosing Hemangioma of Ovary with Stromal Luteinization Masquerading as Sex Cord-Stromal Tumor on Intraoperative Consultation

Anastomosing hemangiomas (AHs) are benign vascular tumor with rare occurrence in the ovary and the majority being asymptomatic. We report one such case of AH with stromal luteinization. A 35-year-old female had complaints of abdominal pain and heavy menstrual bleeding for 2 years. Her lactate dehydrogenase was markedly raised. Following the clinical suspicion of germ cell tumor, exploratory laparotomy and right salpingo-oophorectomy were done. On frozen section due to extensive stromal luteinization, diagnosis of sex cord-stromal tumor was suggested. However, the case was finally diagnosed with AH with extensive stromal luteinization. This case highlighted the potential mimics of AH due to coexistent raised biomarkers and secondary changes, thereby posing a diagnostic dilemma on intraoperative consultation.

Microcystic stromal tumor of the ovary: a recurrent case with somatic CTNNB1 missense mutation

Microcystic stromal tumors (MCSTs) of the ovary are rare sex cord-stromal tumors that are considered benign neoplasms because almost all cases display unilateral, localized lesions and have benign outcomes, except for one recurrent case with familial adenomatous polyposis and another initial metastatic case with a CTNNB1 mutation. We report herein a sporadic case that relapsed as intra-abdominal spread 9 years and 1 month after primary left salpingo-oophorectomy for torsion of the ovarian tumor pedicle. The tumor relapsed as multiple disseminations at the subabdominal wall, Douglas pouch, and omentum. Histologically, the tumor cells formed microcysts and infiltrated the surrounding adipose tissue, similar to the invasive implants of ovarian epithelial borderline tumors. Mutation analysis of the recurrent tumor revealed a somatic CTNNB1 p.S33Y activated missense mutation and a germline KDR p.Q472H variant. In conclusion, long-term clinical follow-up may be needed to detect any recurrence of MCST, irrespective of familial adenomatous polyposis.

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.

Microcystic stromal tumour of testis

Within the group of gonadal sex cord-stromal tumours, microcystic stromal tumour (MCST) is a rare entity. In the literature, most case series and reviews discussed MCST arising in the ovary, only one case-report concerned a testicular MCST. We present a Caucasian man in his late 30s, who presented with an MCST in his right testis. The tumour was encapsulated and composed of vaguely lobulated cellular nodules and cystic spaces with bland spindle cells and hyalinised fibrous stroma. By immunohistochemistry, the tumour cells expressed cluster designation 10, androgen receptor, steroidogenic factor-1 and nuclear beta-catenine, and there was focal nuclear expression of cyclin D1. Molecular diagnostics confirmed the presence of an exon 3 mutation (c.98C>T) in the CTNNB1 gene. These features are similar to MSCT described in the ovary. Clinical follow-up (more than 1 year) was uneventful.Although the clinical and radiological presentation was that of a possible malignant testicular lesion, this entity is benign.

Yolk Sac Tumor of the Ovary: A Report of 150 Cases and Review of the Literature

One hundred fifty yolk sac tumors (YSTs) of the ovary in patients from 1 to 61 (mean: 21.5) years of age are described; 75% of the patients were in the second and third decades and only 1 was above 50 years of age. The clinical manifestations were typically related to a fast-growing adnexal mass; endocrine manifestations (hirsutism) were present in only 2 cases. The tumors were all unilateral and 70% were ≥15 cm; an associated dermoid cyst was present in 20 cases. The tumors were solid and cystic in 57% of the cases, 25% were multicystic, and 18% uniformly solid. The solid tissue was typically tan to pink or yellow and often friable with hemorrhage and necrosis; smaller solid neoplasms were sometime uniformly yellow. The most common histologic pattern was reticular composed of an irregular meshwork of spaces that was conspicuous in 68% of the neoplasms but present to at least a minor degree in all of them. That appearance almost always merged with small to large cysts that were prominent in about 40% of tumors. In 25% of the tumors, cysts sometimes associated with a cellular stroma (the polyvesicular pattern), were present but conspicuous in only half these cases. One third of the tumors had a labyrinthine pattern, 22% glands, and 6% a festoon pattern. Papillae with a central blood vessel (Schiller-Duval bodies) were seen in one-third of the tumors but were numerous in only 5% of them. Nonspecific appearing papillae were seen in 10% of the tumors. A solid growth of cells with pale cytoplasm was seen in one-third of the tumors but was conspicuous in only half of that subset. The solid appearance was typically reminiscent of that of dysgerminoma, but lacked the septa and lymphocytic infiltrate of that neoplasm. Nine tumors had a component of cells with scant cytoplasm resulting in a blastema-like appearance and 3 had cells with abundant clear cytoplasm. Cords and clusters of cells were common but did not dominate the microscopic appearance. The stroma typically had a nonspecific collagenous to edematous appearance. Stromal luteinization was seen in 12 tumors; in 5 this was likely due to the patient being pregnant. Two tumors had minor foci of cells that resembled hepatocytes. Hyaline bodies were seen in most of the tumors and were often conspicuous. The neoplastic cells typically had modest amounts of lightly staining cytoplasm and only mild nuclear pleomorphism. Cells lining cysts were often flattened sometimes resulting in a deceptively innocuous appearance. Many of the tumors (mostly consultation cases), caused diagnostic difficulty; tumors in the differential diagnosis included clear cell carcinoma, embryonal carcinoma, Sertoli-Leydig cell tumor, and juvenile granulosa cell tumor. The patient age and marked elevation of the serum alpha-fetoprotein level (if measured) is helpful in many of these considerations. The overtly malignant gross appearance of most YSTs contrasts with certain other tumors in the differential and the association of some YSTs with dermoid cyst and many clear cell carcinomas with endometriosis may be helpful. The vast majority of ovarian YSTs are dominated microscopically by merging of reticular and cystic patterns which, although focally mimicked by other neoplasms, are in general characteristic, and distinctive features of other neoplasms are absent. Immunohistochemistry, particularly for alpha-fetoprotein and glypican 3, and lack of staining for various markers of other neoplasms is helpful but overlap exists and these results must be considered in the context of the overall clinical, gross, and microscopic features. YSTs dominated by hepatoid and glandular features are rare and their categorization as YSTs should be done cautiously if thoroughly sampled tumors show no evidence of classic features of YST emphasized herein and first elaborated by the Danish investigator Gunnar Teilum whose seminal observations have stood the test of time.

Ovarian microcystic stromal tumour: From morphological observations to syndromic associations

Microcystic stromal tumour (MST) is a rare, usually benign, ovarian neoplasm characterised morphologically in its classic form by a distinctive triad of features comprising microcysts, solid cellular regions and fibrous stroma. Variant morphology also occurs, including the presence of nests, tubules, cords, and signet ring cells. Immunohistochemically, this neoplasm is characterised by diffuse nuclear expression of β-catenin, cyclin D1, WT1 and SF1, as well as diffuse staining with FOXL2 and CD10. Inhibin and calretinin are typically negative. At the genomic level, these neoplasms harbour mutually exclusive mutations in CTNNB1 or APC genes with the former being significantly more common. This molecular characteristic raises possible links to other rare ovarian lesions including solid pseudopapillary tumour, signet-ring stromal tumour and Sertoli cell tumour. Rarely, MST is an extracolonic manifestation of familial adenomatous polyposis (FAP) and serves as a sentinel event that could trigger the identification of the syndrome. Herein, we review the published literature on ovarian MST and provide practical advice for pathologists reporting these rare neoplasms.

A 46-Year-Old Woman with Primary Infertility and a Diagnosis of Microcystic Stromal Tumor of the Ovary Confirmed by Histology and Gene Sequencing: A Case Report and Review of the Literature

Patient: Female, 46-year-old

Final Diagnosis: Microcystic stromal tumor of the ovary

Symptoms: Abdominal pain • vaginal bleeding

Medication: —

Clinical Procedure: —

Specialty: Pathology

Sclerosing stromal tumour: a clinicopathological study of 100 cases of a distinctive benign ovarian stromal tumour typically occurring in the young

AIMS

Since the sclerosing stromal tumour (SST) of the ovary was first described in 1973, few studies have expanded upon its histological features or overlap with other tumours. We thus investigate these aspects based on our experience with 100 cases.

METHODS AND RESULTS

The patients, 14 of whom were pregnant, ranged from 12 to 63 years (median = 26 years). Ten patients had hormonal manifestations (seven oestrogenic, three androgenic). Bilateral ovarian involvement was present in two cases. Size ranged from 1 to 23 cm (mean = 8.4 cm). Most tumours were solid and white with focal yellow areas; oedema with cystic degeneration (seen in 25 cases) resulted in eight being predominantly cystic. On microscopic examination, alternating cellular and paucicellular areas (pseudolobulation) were prominent in 94 cases but seen to a limited degree in the remaining neoplasms. Admixed spindled and luteinised cells were present in all tumours, but 13 demonstrated mainly spindled cells and 19 demonstrated mainly lutein cells; 14 of the latter were from pregnant patients. The stroma was typically oedematous or collagenous, but in 14 cases was prominently hyalinised and, in four, myxoid. Prominent vascularity was present in most cases. The mitotic rate ranged from 0 to 8/10 high-power fields (HPF), but most demonstrated <1/10 HPF.

CONCLUSIONS

The differential diagnosis of SST is broad, including fibromas, thecomas, solitary fibrous tumours, pregnancy luteomas, myxomas, other ovarian sex cord-stromal tumours with sclerosis and, rarely, Krukenberg tumours. Strict adherence to the requirement of pseudolobulation, prominent (usually ectatic) vessels, and lutein cells and fibroblasts admixed in a jumbled manner, will distinguish the neoplasm from others in the differential.

Endometrioid Tubal Intraepithelial Neoplasia and Bilateral Ovarian Microcystic Stromal Tumors Harboring APC Mutations: Report of a Case

Microcystic ovarian tumor of the ovary is a neoplasm of presumed stromal derivation characterized by CTNNB1 or APC alterations leading to nuclear β-catenin expression. This tumor has been described as unilateral and indolent in previously published series. The recently characterized endometrioid tubal intraepithelial neoplasia (eTIN) is an epithelial proliferation of the tube also characterized by nuclear β-catenin staining, and distinct from high-grade serous precursors. Herein, a case of bilateral ovarian microcystic stromal tumors and multiple left tubal eTINs discovered incidentally in a 41-yr-old woman with previous history of colon cancer is described. Both ovarian and tubal proliferations harbored APC inactivating mutations. Although history of familial adenomatous polyposis or a germline defect could not be confirmed, the history of colon cancer at a young age and the shared APC mutation in both microcystic stromal tumor and eTIN were suggestive of this possibility. Microcystic stromal tumor has been described in the setting of familial adenomatous polyposis syndrome. This case adds to this association by documenting for the first time bilateral ovarian involvement by microcystic stromal tumor. Moreover, it alerts to the possibility of endometrioid neoplasia of the fallopian tube secondary to APC mutations, a previously undescribed phenomenon.

Ovarian microcystic stromal tumor with omental metastasis: the first case report and literature review

Background

Microcystic stromal tumor (MCST) of the ovary is an extremely rare subtype of sex cord-stromal neoplasm first described by Irving and Young in 2009. Tumors from all previously reported cases (fewer than 40 total) were benign, but one was a case of ovarian MCST that reoccurred.

Case presentation

Herein, we present a unique single case of ovarian MCST with omental metastasis in a 47-year-old Chinese female along with its histologic and immunohistochemical profile and genetic alterations. The tumor exhibited the previously described classic microscopic features and immunoprofiles of MCST. The tumorlet in the omentum presented the same histological structures and characteristically expressed β-catenin protein (localized in the nucleus). Molecular analysis identified a point mutation (c.98C > G) in exon 3 of CTNNB1.

Conclusions

To the best of our knowledge, no such report has been documented for ovarian MCST with omental metastasis. The study may provide new insights into the tumor biology of MCST and provide a better understanding of this rare entity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00812-1.

Ovarian microcystic stromal tumor with significant bizarre nuclei: A case report

RATIONALE

Ovarian microcystic stromal tumor is a relatively rare tumor type, which is characterized by morphology with microcyst structure, solid cellular areas, and hyalinized fibrous stroma. The most reported tumors were stage I with good prognosis.

PATIENT CONCERNS

We report a case of a 33-year-old woman with primary ovarian microcystic stromal tumor with significant bizarre nuclei. We describe the clinical, histopathological, and immunohistochemical findings and review the English literatures. So far, as we know, the patient presented here is a rare case of ovarian microcystic stromal tumor with prominent bizarre nuclei accounting for about 50% of the tumor cells.

DIAGNOSES

She was diagnosed with ovarian microcystic stromal tumor with significant bizarre nuclei.

INTERVENTIONS

The right ovarian tumor was resected laparoscopically on October 19, 2018.

OUTCOMES

Up to now, the patient is free of disease at 19 months of follow-up.

LESSONS

This is a rare case of ovarian microcystic stromal tumor with obvious bizarre nuclei. This report will contribute to expand the morphological spectrum of ovarian microcystic stromal tumor.

Practical roles for molecular diagnostic testing in ovarian adult granulosa cell tumour, Sertoli-Leydig cell tumour, microcystic stromal tumour and their mimics

Within the last decade, molecular advances have provided insights into the genetics of several ovarian sex cord-stromal tumours that have otherwise been enigmatic. Chief among these advances are the identification of FOXL2, DICER1 and CTNNB1 mutations in adult granulosa cell tumours, Sertoli-Leydig cell tumours (SLCTs), and microcystic stromal tumours (MCSTs), respectively. As access to molecular diagnostic laboratories continues to become more widely available, the potential roles for tumour mutation testing in the pathological diagnosis of these tumours merit discussion. Furthermore, links to inherited cancer susceptibility syndromes may exist for some women with SLCT (DICER1 syndrome) and MCST [familial adenomatous polyposis (FAP)]. This review will address practical issues in deciding when and how to apply mutation testing in the diagnosis of these three sex cord-stromal tumours. The pathologist's role in recommending referral for formal risk assessment for DICER1 syndrome and FAP will also be discussed.

Female adnexal tumors of probable Wolffian origin: morphological, immunohistochemical, and molecular analysis of 15 cases

Female adnexal tumors of probable Wolffian origin are rare and present a diagnostic challenge due to their morphological and immunohistochemical overlap with more common ovarian and broad ligament entities. We evaluated the morphological, immunohistochemical, and molecular features of 15 tumors of probable Wolffian origin. Patients ranged from 32 to 69 (mean 47) years and tumors from 1.8 to 30 (mean 10) cm. All except one arose in para-adnexal soft tissues. Follow-up was available for six patients, five of whom were alive and well, while the sixth, who had extra-adnexal disease at diagnosis, died from unrelated causes. The following patterns were noted: tubular (all tumors), solid 11/15 (73%), sieve-like 7/15 (47%), and reticular 1/15 (7%). A myxoid background was present in 3/15 (20%) of tumors and eosinophilic luminal secretions in 11/15 (73%). Most tumors (12/15, 80%) had low-grade nuclear atypia, while three showed foci with scattered high-grade atypia. Mitotic index ranged from 0 to 17 (mean 4) per ten high-power fields. Tumors were positive for pankeratin and negative for TTF-1. EMA, GATA3, and PAX8 were positive in 2/10 (20%; focal), 3/15 (20%; focal), and 1/15 (7%; focal) of tumors, respectively. CD10, SF-1, calretinin, inhibin, ER, PR, cytokeratin 7, and WT1 were variably expressed. Pathogenic mutations were rare and included STK11 (n = 3), APC (n = 1), and MBD4 (n = 1). Copy number variations were detected in the three tumors with STK11 mutations and a myxoid background. These data demonstrate that female adnexal tumors of probable Wolffian origin are morphologically and immunohistochemically diverse, but infrequently harbor pathogenic mutations. However, their lack of mutations in contrast to their mimickers may be a valuable tool in diagnostically difficult cases.

Ovarian Microcystic Stromal Tumor: A Case Report and Literature Review

Background: Microcystic stromal tumor is a recently described subtype of ovarian tumor characterized by microcystic pattern and diffuse immunoreactivity for CD10, vimentin, and β-catenin and negative for EMA. However, its diagnostic criterion and standard treatment remain unclear. Case presentation: We report a rare case of a left side microcystic stromal tumor with diameter about 7 cm in a 25-year-old female and summarize all cases of MCST reported in this study. The present patient underwent left ovarian tumor resection. Generally, the tumor was solid and cystic mixed. Immunohistochemically, the tumor was expressed CD10, WT1, cyclin D1 and vimentin, and nuclear immunoreactivity for β-catenin but negative for α-inhibin, calretinin, CK AE1/AE3, PLAP, SALL-4, CK7, P53, EMA, CD99, AFP, desmin, CgA, E-cadherin, and melanA. Conclusion: Unilateral ovary, solid-cystic, and a larger than 4-8 cm pelvic mass without serious abdominal pain are its clinical features. The immunophenotype of vimentin+/CD10+/WT-1+/β-catenin+(nuclei)/cyclin D1+ is supportive of diagnosis. For these patients, unilateral oophorectomy dissection could be selected.

Ovarian tumors: a survey of selected advances of note during the life of this journal

The author reviews highlights of advances in knowledge concerning ovarian tumor pathology since the time of an essay in the first issue of this Journal written by Dr Robert E. Scully, who, both before and for several decades after the Journal was instituted, made many original contributions to the field and was the major architect of the 1973 World Health Organization classification of ovarian tumors which was much more clear and logical than prior ones. The current review considers the neoplasms in essentially the same order as was done in the first issue of this journal and presents a personal look at the highlights of new information concerning various well-known categories, surface epithelial, germ cell, sex cord-stromal, metastatic neoplasms and briefly, benign so-called tumor-like lesions. Some of the most notable developments are as follows: (1) an orderly approach to the classification of implants of serous borderline tumors into noninvasive and invasive categories; (2) recognition of distinctive micropapillary patterns seen in some borderline tumors and low-grade carcinomas; (3) a remarkable propensity for some endometrioid carcinomas to mimic sex cord- stromal tumors; (4) appreciation of the differences between primary mucinous tumors of intestinal and müllerian types; (5) the importance of distinguishing within primary mucinous carcinomas between expansile and destructive stromal invasion; (6) emphasis on the diagnosis of immature teratoma being based on the presence of primitive-embryonic-appearing tissues; (7) appreciation of variant morphology of cases of struma ovarii which may lead to significant diagnostic problems; (8) subdivision of granulosa cell tumors into adult and juvenile types because of the differing features of the two groups including in the second category the propensity for more malignant neoplasms to be mimicked; (9) recognition of a distinctive form of Sertoli-Leydig cell tumor, the retiform variant, with a propensity to occur in the young; (10) appreciation of a unique highly malignant neoplasm that typically afflicts the young and may be associated with hypercalcemia, so-called small cell carcinoma of hypercalcemic type; (11) greater awareness than was hitherto the case of the propensity for metastatic intestinal adenocarcinoma to mimic primary endometrioid carcinoma and similarly for metastatic mucinous carcinomas to simulate primary mucinous cystic tumors; (12) recognition of the distinctive features of low-grade appendiceal mucinous neoplasms that spread to the ovary and are typically associated with pseudomyxoma peritonei; and (13) appreciation that the histologic spectrum seen in cases of Krukenberg tumor is broader than often previously thought.

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.

Granulosa Cell Tumors of the Ovary With Prominent Thecoma-like Foci: A Report of 16 Cases Emphasizing the Ongoing Utility of the Reticulin Stain in the Modern Era

Sixteen adult granulosa cell tumors which had conspicuous zones of cells with pale cytoplasm imparting a resemblance to thecoma are reported. The neoplasms occurred in patients from 38 to 86 yr of age, the majority being over 55 yr of age. Ten tumors were incidental findings, the remainder being associated with symptoms or signs related to an adnexal mass. All the tumors were unilateral, typically small, usually under 5 cm, with only 3 being larger. With 1 exception they were uniformly solid and were typically entirely or focally yellow on sectioning. Microscopic examination typically showed a nodular pattern of growth constituted by cells with moderate to abundant pale cytoplasm; the cells resembled those seen in most thecomas. The nodules occasionally became confluent and focally a diffuse pattern was seen. Typical foci of adult granulosa cell neoplasia in the form of foci of conspicuous epithelial differentiation were absent or rare in most cases but were seen in subtle form in 6 cases and overtly in 3. A few tumors had other features seen in some thecomas, hyaline plaques, sclerosis, and calcification. Reticulin stains were examined in 13 cases and showed that the thecoma-like foci exhibited a dearth of reticulum indicating that those areas were predominantly of granulosa cell nature. Most adult granulosa cell tumors have cells with scant cytoplasm; occasional tumors have abundant eosinophilic cytoplasm, so-called luteinized adult granulosa cell tumors. That some granulosa cell tumors have the cytoplasmic features described herein has occasionally been noted but the resemblance to thecoma has not been emphasized to the best of our knowledge and in the past such tumors may have been misdiagnosed as thecoma, the referral diagnosis in 6 of our cases. A reticulin stain is of crucial aid in indicating the epithelial nature of the thecoma-like foci in these cases. Given the small size of the majority of the tumors the distinction between a small adult granulosa cell tumor and thecoma does not have significant prognostic or therapeutic implications in most cases but awareness of this feature of a small subset of adult granulosa cell tumors is warranted. Our findings have import to the diagnosis of thecoma which is uncommon if strict criteria, including exclusion of granulosa tumors of the type described, are used.

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.

Ovarian microcystic stromal tumor: Radiologic-pathologic correlation

Ovarian microcystic stromal tumor (MST) is characterized by microcysts, solid cellular regions with lobulated growth, and collagenous or fibrous stroma forming hyaline plaques. While several reports have evaluated the unique pathologic and immunohistochemical profile of these tumors, there has been limited description of the radiologic findings of ovarian microcystic stromal tumor in the literature. We present a case of a 66 year old female who presented for evaluation of a new cystic pelvic mass found to have ovarian microcystic stromal tumor. To our knowledge, this is one of the first reports to evaluate the radiologic features associated with this tumor. An enhanced understanding of the correlation between imaging appearance and specific histopathologic findings may aid in the early recognition of this rare neoplasm.

Solid pseudopapillary neoplasm (SPN) of the testis: Comprehensive mutational analysis of 6 testicular and 8 pancreatic SPNs

BACKGROUND

Recently, we came with the theory of a possible relationship between a group of testicular and pancreatic tumors. We used one case of a pancreatic analogue solid pseudopapillary neoplasm of the testis composed partially of areas reminiscent of solid pseudopapillary neoplasm (SPN) of the pancreas and partially of structures identical to primary signet ring stromal tumor of the testis (PSRSTT) as a connecting link between these two entities. After demonstrating that PSRSTT and pancreatic analogue SPN of the testis share the same immunoprofile and genetic features characteristic for pancreatic SPN, we came to the conclusion that pancreatic analogue SPN of the testis and PSRSTT represent a morphological spectrum of a single entity and that both are related to the pancreatic SPN.

DESIGN

The aim of this study is to present a series of 6 cases of testicular tumors, which lacked the signet ring cell component and were thus morphologically very similar to the SPN of the pancreas. The goal of this study is to compare the genetic background of these testicular tumors that are obviously related to the PSRSTT/pancreatic analogue SPN of the testis with the series of 8 pancreatic SPN.

RESULTS

The mutational analysis revealed an oncogenic somatic mutation in the exon 3 of the CTNNB1 (β-catenin) gene in all analyzable (5/6) testicular and all pancreatic (8/8) tumors. The immunoprofile (positivity with β-catenin, CD10, vimentin, NSE, CD56, and negativity with inhibin, calretinin, chromogranin) was identical in all testicular and pancreatic tumors.

CONCLUSION

This study expanded the morphological spectrum of the PSRSTT/pancreatic analogue SPN of the testis by adding 6 cases without the signet ring cell component. Considering the obvious analogy of PSRSTT/pancreatic analogue SPN of the testis/SPN of the testis and their relationship to the pancreatic SPN we propose the collective term "solid pseudopapillary neoplasm of the testis" for these tumors. The mutational profile of the SPN of the testis and pancreas was the same in both groups of tumors which we consider as a final proof that SPN of the testis is identical to the SPN of the pancreas.

Microcystic Stromal Tumor of Testicle: First Case Report and Literature Review

Microcystic stromal tumor (MCST) is a rare subtype of sex cord-stromal neoplasm. Tumors from all 31 previously reported cases were located in the ovary. Herein, we present a unique case of a right-side testicular tumor in a 33-year-old Chinese male. The tumor is composed of predominantly lobulated cellular nodules separated by hyalinized fibrous stroma and they expressed CD10, β-catenin (nuclear), and cyclin D1. Molecular analysis identified a point mutation (c.110C>G) in exon 3 of CTNNB1. The histopathological features, immunohistochemistry profiles, and molecular analysis of this tumor were consistent with MCST of the ovary. Therefore, a diagnosis of MCST of the right testicle was determined. To the best of our knowledge, this is the first case of MCST occurring in the testicles. The study may provide new insights to the tumor biology of MCST and a better understanding of this rare entity.

Ovarian sex cord-stromal tumours and their mimics

Sex cord-stromal tumours of the ovary include many of the most morphologically intriguing ovarian neoplasms and albeit many of them are rare, they factor into the differential diagnosis more often than their frequency might suggest. The most common malignant form, the adult granulosa cell tumour, may grossly simulate various surface epithelial neoplasms. Microscopically, confusion with endometrioid carcinoma may occur because the cords and microfollicles of the granulosa cell tumour may be mimicked by endometrioid carcinoma and the latter may have pale nuclei with nuclear grooves. Thorough sampling generally resolves this differential and if not immunohistochemistry aids. Although the adult granulosa cell tumour typically has cells with scant cytoplasm in some cases the tumour cells are luteinised and others have cells with abundant pale cytoplasm. A reticulum stain may be of great aid in indicating whether cells of the type just noted are of granulosa or theca nature. Variations in the morphology of the juvenile variant of granulosa cell tumour that can be diagnostically challenging include those that have a macronodular pattern with scant follicular differentiation, those with marked sclerosis, and those that are unusually pleomorphic. The uncommon but histologically varied Sertoli-Leydig cell tumour is considered, emphasis being placed on the most recently described variant, the retiform pattern, with its potential to mimic surface epithelial neoplasms and even mixed mesodermal tumours. Considering the usual young age of the patient may be paramount in making this tumour come to the mind of the pathologist. The rare pure Sertoli cell tumour is briefly noted as is the sex cord tumour with annular tubules, well known because of its association in some cases with Peutz-Jeghers syndrome. Most do not have that association, however, but have their own interesting features including a greater than average risk, among sex cord stromal tumours, of nodal metastasis and progesterone production, and an occasional development from them of an otherwise typical Sertoli cell tumour. The stromal family includes the common fibroma which is challenging when it is cellular with some mitotic activity and the approach to such neoplasms is reviewed. Emphasis in the consideration of thecoma is placed on its typical cytological features and the overlap with what may be seen in some adult granulosa cell tumours. The review concludes with three fascinating pure stromal tumours all described within the last several decades: the sclerosing stromal tumour, the unusual luteinised thecoma associated with sclerosing peritonitis and the microcystic stromal tumour. The first is sometimes misdiagnosed when pure stromal neoplasms of other types are vascular and may have pseudolobules and it is essential that the pseudolobules of the sclerosing stromal tumour contain a haphazard admixture of fibroblasts and weakly luteinised cells. The remarkable tumours associated with peritonitis exhibit brisk mitotic activity but appear not to have a metastatic potential; they can cause significant problems because of the sclerosing peritonitis. The microcystic stromal tumour may mimic a steroid cell tumour or thecoma but unlike them is inhibin and calretinin negative, and stains for CD10 and β-catenin. It often shows bizarre nuclei atypia but limited mitotic activity and appears to be clinically benign on the basis of still limited experience.

'Microcystic pattern' should be recognised as part of the morphological spectrum of solid-pseudopapillary neoplasm of the pancreas

AIM

Solid pseudopapillary neoplasm (SPN) is an uncommon pancreatic tumour characterised by solid and pseudopapillary growth patterns. We have observed SPNs can show a microcystic pattern (microcystic SPN), which has been poorly described and may be confused with microcystic neoplasms. We conducted the present study to clarify the clinicopathological and immunohistochemical features of microcystic SPNs.

METHODS AND RESULTS

We examined a consecutive series of 44 SPNs and 10 serous cystadenomas (SCAs), and classified them into 13 microcystic SPNs (29.5%) and 31 conventional SPNs (70.5%). Clinicopathological analysis, immunohistochemical staining and mucin histochemistry were performed. Clear cell change, hyalinised stroma and haemorrhage were observed significantly more frequently in the microcystic SPNs compared to the conventional SPNs. Immunohistochemically, the microcystic SPNs showed significantly lower frequencies of CD10 (0%) and CD56 expression (62%) compared to the conventional SPNs (87%; P < 0.001, 90%; P < 0.0085, respectively). There were no significant differences in other clinicopathological and immunohistochemical features between the two groups (i.e. the nuclear expression of β-catenin, E-cadherin, progesterone receptor (PgR), lack of forkhead box (Fox)L2 and occasional oestrogen receptor (ER), AE1/AE3 expression). Microcystic SCAs lack such a characteristic immunophenotype. The myxoid stroma of microcystic SPNs contained hyaluronan revealed by Alcian blue stain with hyaluronidase digestion.

CONCLUSION

We thus conclude that the microcystic pattern should be recognised as a part of the morphological spectrum of SPNs. Our findings may contribute to the correct diagnosis of the pancreatic neoplasms with the microcystic pattern. In addition, we speculate that stromal change caused by an accumulation of hyaluronan may contribute to the microcystic pattern of SPN.

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.

Microcystic stromal tumor resected by laparoscopic surgery

We report a case of microcystic stromal tumor (MCST) resected by laparoscopy. MCST is a very rare ovarian tumor with distinctive microcystic features and a characteristic stromal tumor immunopheno-type. The present case was a 26-year-oId woman who underwent laparoscopic surgery for suspected endometrial cyst of the left ovary. The mass was 8 cm in size and contained bloody fluid, and after attempting cystectomy, we eventually performed left salpingo-oophorectomy with a final postoperative pathological diagnosis of MCST. Although MCST has not yet been associated with malignancy, there are reported links to mutations in the β-catenin gene, and long-term prognosis is still unknown. As MCST resection by laparoscopy has not yet been fully described in the literature, the current case provides an example of when an unexpected, potentially malignant mass is encountered during routine cystectomy and details its subsequent management laparoscopically.