Interphase fluorescence in situ hybridization analysis of chromosome 12p abnormalities is useful for distinguishing epidermoid cysts of the testis from pure mature teratoma

Gonadal Teratomas: A State-of-the-Art Review in Pathology

Teratomas are neoplasms arising from germ cells and encompass tissues derived from two or more embryonic germ layers, including ectoderm, mesoderm, and endoderm. These tumours typically localize along the midline or in paramedian positions and can manifest as gonadal (20%) or extragonadal (80%) entities. Although gonadal teratomas are uncommon, they represent the predominant type of gonadal tumour in the paediatric population. They comprise approximately 20-25% of all ovarian tumours in females and about 3-5% of all testicular tumours in males. Ovarian teratomas exhibit a higher incidence in early childhood and adolescence, whereas testicular teratomas are more prevalent during the first three months of life and between the ages of 15 and 19. While the majority of paediatric gonadal teratomas are benign, malignant or mixed variants may also arise, necessitating more aggressive therapeutic interventions.

Extragonadal germ cell tumors: A clinicopathologic study with emphasis on molecular features, clinical outcomes and associated secondary malignancies

Extragonadal germ cell tumors (EGCTs) are rare, representing <5% of all germ cell tumors (GCTs). Whilst EGCTs share morphological and immunohistochemical features with their gonadal counterparts, they tend to be more aggressive and are frequently associated with secondary somatic malignancies. The aim of our study was to evaluate the clinical, morphological and immunohistochemical features, and to analyze tumors for chromosomal abnormalities of 12p, in addition to any novel genetic alterations, in a series of EGCTs. Seventy-seven EGCTs were included. Anterior mediastinum was the most common anatomic site, followed by central nervous system, retroperitoneum, sacroccygeal area, and neck. Whole genome SNP array identified isochromosome 12p in 26% of tumors. Additional cytogenetic abnormalities included the presence of gain of chr 21 in 37% of tumors. Somatic-type malignancies were identified in 8% of patients. Disease progression (metastasis and/or recurrence) was documented in 8 patients, most of whom died from their relapse. Three patients who died of disease had somatic-type malignancies. Mediastinal seminomas had a significantly better overall survival when compared to mediastinal non-seminomatous GCTs. Our study demonstrates that EGCTs share similar histologic features, but diverse clinical outcomes compared to their gonadal counterparts. Outcomes vary according to anatomic location and histologic subtypes. Our data corroborate that somatic-type malignancies are frequently encountered in mediastinal EGCTs and that their presence portends a poorer prognosis.

Spontaneous rupture‑induced life‑threatening mediastinal mixed germ cell tumor: A case report and therapeutic considerations

Spontaneous rupture and hemorrhage of mediastinal germ cell tumors is a rare occurrence. In the current report, the case of a 20-year-old male patient who was admitted with chest tightness and dyspnea is presented. An urgent chest CT scan revealed a large tumor in the right anterior mediastinum, measuring ~12 cm in diameter, with associated intratumoral hemorrhage. An emergency thoracotomy was performed to excise the lesion, which revealed that the bleeding was caused by a ruptured tumor. Postoperative pathological findings revealed a mediastinal mixed germ cell tumor consisting of four pathological types: Embryonal carcinoma, seminoma, yolk sac tumor and immature teratoma. Postoperatively, the patient showed marked improvement in the symptoms of dyspnea. However, the follow-up outcome was poor, and the patient succumbed 2 months after surgery. To the best of our knowledge, there are no reports of rupture and hemorrhage involving >4 mixed germ cell tumors. In the present report, the experience of the treatment of the patient is summarized, and literature was reviewed to improve clinicians' awareness of the disease.

Molecular Biology of Pediatric and Adult Ovarian Germ Cell Tumors: A Review

Ovarian germ cell tumors (OGCTs) are rare in adults; indeed, they occur predominantly in children, adolescents, and young adults, and they account for approximately 11% of cancer diagnoses in these groups. Because OGCTs are rare tumors, our current understanding of them is sparse; this is because few studies have investigated the molecular basis of pediatric and adult cancers. Here, we review the etiopathogenesis of OGCTs in children and adults, and we address the molecular landscape of these tumors, including integrated genomic analysis, microRNAs, DNA methylation, the molecular implications of treatment resistance, and the development of in vitro and in vivo models. An elucidation of potential molecular alterations may provide a novel field for understanding the pathogenesis, tumorigenesis, diagnostic markers, and genetic peculiarity of the rarity and complexity of OGCTs.

Molecular Biology of Pediatric and Adult Male Germ Cell Tumors

Simple Summary

Although testicular germ cell tumors (TGCTs) are rare pediatric malignancies, they are the most common malignancies in young adult men. The similarities and differences between TGCTs in adults and children, taking into account the clinic presentation, biology, and molecular changes, are underexplored. In this paper, we aim to provide an overview of the molecular aspects of TGCTs, drawing a parallel between the findings in adult and pediatric groups.

Abstract

Cancer is a leading cause of death by disease in children and the second most prevalent of all causes in adults. Testicular germ cell tumors (TGCTs) make up 0.5% of pediatric malignancies, 14% of adolescent malignancies, and are the most common of malignancies in young adult men. Although the biology and clinical presentation of adult TGCTs share a significant overlap with those of the pediatric group, molecular evidence suggests that TGCTs in young children likely represent a distinct group compared to older adolescents and adults. The rarity of this cancer among pediatric ages is consistent with our current understanding, and few studies have analyzed and compared the molecular basis in childhood and adult cancers. Here, we review the major similarities and differences in cancer genetics, cytogenetics, epigenetics, and chemotherapy resistance between pediatric and adult TGCTs. Understanding the biological and molecular processes underlying TGCTs may help improve patient outcomes, and fuel further investigation and clinical research in childhood and adult TGCTs.

Assessment of isochromosome 12p and 12p abnormalities in germ cell tumors using fluorescence in situ hybridization, single-nucleotide polymorphism arrays, and next-generation sequencing/mate-pair sequencing

The identification of isochromosome 12p [i(12p)] and 12p gains have significant clinical utility in the diagnosis of germ cell tumors (GCTs). We have summarized the results of fluorescence in situ hybridization (FISH) assays to identify i(12p), performed in a Clinical Laboratory Improvement Amendments (CLIA)-validated setting for 536 specimens. In addition, the American Association for Cancer Research (AACR) Project GENIE registry and The Cancer Genome Atlas (TCGA) data sets were evaluated for chromosome 12p gains, and a limited number of cases were concurrently evaluated using FISH, single-nucleotide polymorphism (SNP) arrays and next-generation sequencing (NGS; including mate-pair sequencing). Specimens submitted for FISH testing were frequently from potential sites of metastases (male: 70.9% and female: 69.3%), and polysomy of chromosome 12 with or without concurrent i(12p) was a frequent finding, seen in 3% (16/536) and 35% (186/536) of cases, respectively. Our analysis suggests that 12p gains are likely to be present in approximately 73% of male GCT and in 32% of female GCT (AACR GENIE, n = 555). When comparing TCGA cases of testicular GCT (n = 149) to combined cases of sarcoma, colorectal, prostate, and urothelial carcinoma (n = 1754), 12p gains had a sensitivity of 77.2% and specificity of 97.3% for GCT. Some advantages of FISH over SNP arrays/NGS include relatively lower cost, rapid turnaround time, the ability to analyze biopsy material with a limited number of tumor cells (50 cells), and the ability to distinguish i(12p) from polysomy. The ability to spatially restrict the analysis to cells of interest is critical, as specimens submitted for testing often have low tumor purity. Disadvantages include false negative results due to an inability to detect segmental gains due to FISH probe design. With the availability of numerous testing modalities, including FISH, SNP arrays, and NGS-based assays, a nuanced understanding of the advantages and disadvantages of each methodology, as has been presented in this study, may inform appropriate testing strategies.

Multitarget fluorescence in situ hybridization diagnostic applications in solid and hematological tumors

Introduction: Multitarget FISH (mFISH) is a technique allowing for simultaneous detection of multiple targets sequences on the same slide through the choice of spectrally distinct fluorophore labels. The mFISH could represent a useful tool in the field of precision oncology.Areas covered: This review discusses the potential applications of mFISH technology in the molecular diagnosis of different solid and hematological tumors, including non-small cell lung cancers, melanomas, renal cell carcinomas, bladder carcinomas, germ cell tumors, and multiple myeloma, as commonly required in the clinical practice.Expert Opinion: In this emerging era of the tailored therapies and newer histo-molecular classifications, there are increasing numbers of predictive and diagnostic biomarkers required for effective clinical care. The mFISH approach may have several applications in the common clinical practice, improving the molecular diagnosis in terms of time, cost and preservation of biomaterial for tumors with a limited amount of tumor available. The mFISH provides several advantages compared to other high-throughput technologies; however, it requires high level of expertise required to interpret complex results.

Fluorescence In Situ Hybridization (FISH) Detection of Chromosomal 12p Anomalies in Testicular Germ Cell Tumors

Gains of genetic material or internal rearrangements of chromosome 12p, including 12p overrepresentation or isochromosome 12p [i(12p)], are observed in virtually all germ cell tumors (GCT), in all histologic subtypes, and from various body locations. The chromosomal region involved in these alterations contains the growth and survival promoting oncogene KRAS (12p12.1). Gains or rearrangements of 12p characterize GCT from in situ to chemoresistant stages. Fluorescence in situ hybridization (FISH) detection of chromosome 12p anomalies is a sensitive and specific test for the diagnosis of germ cell tumors. Here we provide a detailed protocol for FISH detection of isochromosome 12p and chromosome 12p overrepresentation. The method is helpful for diagnosis of germ cell origin, and for selection of patients who may benefit from cisplatin-based chemotherapy.

Rare benign and malignant testicular lesions: histopathology and management

PURPOSE OF REVIEW

The presence of vascular solid tumors within the testicle is considered to be malignant until proven otherwise. However, it is prudent for clinicians to be aware of rare benign and malignant intratesticular lesions as management can differ from the established treatment algorithms for germ-cell tumors.

RECENT FINDINGS

Utilizing certain histopathologic findings can assist with the diagnosis of rare testis tumors. Often times the tumor subtypes are an important consideration in the grading and classification of the disease, which drives management. The multidisciplinary management of rare malignant testis tumors at an experienced center seems to provide optimal patient outcomes. Regardless of the primary treatment, prolonged follow-up for sex cord stromal tumors and other rare testis malignancies is advocated due to the delayed metastatic potential.

SUMMARY

The clinical presentation of rare benign and malignant testis tumors is often similar to that of germ-cell tumors. Likewise, imaging characteristics are also often indistinguishable. However, the management of these rare tumors is often different from the well established treatment algorithms of germ-cell tumors. To that end, it is important for the practicing urologist to be familiar with the current principles of these tumor characteristics and the management.

Prospective molecular and morphological assessment of testicular prepubertal-type teratomas in postpubertal men

In 2016, the World Health Organization classification system of testicular tumors included the new entity prepubertal-type teratoma based on its morphological and molecular profile, and the realization that these tumors may occur in postpubertal men. For treatment and prognostic purposes, it is important to distinguish prepubertal-type teratoma from the usual postpubertal-type teratoma, because the former is benign unlike the latter. The distinction may be challenging. In this study, we investigated clinical, morphological, and molecular criteria for distinguishing prepubertal-type teratoma from postpubertal-type teratoma in a prospective series of pure testicular teratomas. All cases of pure teratoma in postpubertal men assessed at Barts Health NHS Trust or in consultation since the introduction of routine investigation of chromosome 12p status in 2010 were reviewed. Morphological features suggestive of prepubertal-type teratoma were observed in 14 out of 35 cases. All underwent molecular testing and none displayed 12p amplification. Mean tumor size was 16 mm (range 7-28 mm). None had associated germ cell neoplasia in situ or significant atrophy. Four incorporated a well-differentiated neuroendocrine tumor, 1-2 mm in size. Of the ten patients with follow-up information, none have recurred or metastasized. Twenty-one of the 35 cases were diagnosed as postpubertal-type teratoma, mean tumor size 40 mm (range 6-90 mm). One case underwent molecular testing: a tumor of pure skeletal muscle differentiation and possessed 12p amplification. Three cases presented with clinical metastases. Eight cases contained immature areas, ten cases had associated germ cell neoplasia in situ, and 17 cases had severe atrophy of the parenchyma. One case with neither germ cell neoplasia in situ nor atrophy showed necrosis. We conclude that both morphological and molecular features are of help in differentiating prepubertal-type teratoma from postpubertal-type teratoma. In nearly all postpubertal-type teratomas, molecular testing was unnecessary, and merely confirmed the morphological impression in the prepubertal-type teratomas. Our study confirmed the high incidence of well-differentiated neuroendocrine tumors in the prepubertal-type.

Histology, 12p status, and IMP3 expression separate subtypes in testicular teratomas

Introduction

Two types of testicular teratomas are distinguished by the current WHO classification. Prepubertal-type teratomas are benign, while postpubertal-type teratomas are considered malignant with metastatic potential, and are associated with germ cell neoplasia in situ. Prepubertal-type cases have been reported in the adult testis potentially causing confusion and overtreatment. Demonstration of the absence of 12p abnormalities with fluorescence in situ hybridization may facilitate diagnosis. Recently, IMP3 has emerged as a potential marker of malignancy in this context.

Aims

The aim of this study was to assess histological characteristics, IMP3 expression and the presence of 12p abnormalities of pure testicular teratomas.

Results

Thirty-seven cases were studied, 7 patients were children and 30 were adults. Six out of 7 pediatric cases showed no 12p abnormality and were IMP3 positive. Seventy-four percent and 79% of adult cases showed 12p abnormalities and IMP3 expression, respectively. Negative cases were not associated with in situ neoplasia or metastasis, they were smaller (mean, 14 vs 39 mm), showed less histological diversity (2.4 vs 4.0 types of tissues on average) compared to positive cases.

Conclusion

Our study provides further evidence that prepubertal-type (type I) teratomas may appear in adult testes, thus teratomas in adults may be either benign (type I) or malignant (type II). IMP3 expression may aid the distinction between type I and type II teratomas of the postpubertal testis even when GCNIS and 12p status cannot be assessed.

Electronic supplementary material

The online version of this article (10.1007/s00428-020-02771-2) contains supplementary material, which is available to authorized users.

Extragonadal germ cell tumors: Not just a matter of location. A review about clinical, molecular and pathological features

Extragonadal germ cell tumors (EGGCTs) are uncommon neoplasms, which arise in anatomical locations other than gonads. The pathogenesis of these neoplasms is still poorly understood and it is a matter of debate if they really represent extragondal primary neoplasms or rather extragondal metastasis from occult gonadal neoplasms. The actual observations suggest that EGGCTs represent a unique entity, so their biology and behavior are substantially different from gonadal counterparts. The diagnosis of EGGCTs is often challenging, and differential diagnosis is particularly wide. Nevertheless, a correct diagnosis is essential for the correct management of the patient. We summarize the state of art about EGGCTs, with particular emphasis on diagnosis and prognosis.

Epidermoid Cyst of the Testis: Sonographic Characteristic Appearance

Intratesticular epidermoid cysts are rare, benign, well-defined, and solitary keratinized intratesticular lesions. They usually present as a painless, discrete, and firm swollen area before being diagnosed. Preoperative diagnosis of epidermoid cysts is often difficult. Sonography is a useful imaging modality in the preoperative assessment of testicular lesions. Although it is difficult to distinguish epidermoid cysts from germ cell tumors, certain sonographic characteristics such as the classical “onion-peel” appearance, the negative tumor markers, and the underlying symptoms should raise the suspicion of epidermoid cysts.

The World Health Organization 2016 classification of testicular germ cell tumours: a review and update from the International Society of Urological Pathology Testis Consultation Panel

Since the last World Health Organization (WHO) classification scheme for tumours of the urinary tract and male genital organs, there have been a number of advances in the understanding, classification, immunohistochemistry and genetics of testicular germ cell tumours. The updated 2016 draft classification was discussed at an International Society of Urological Pathology Consultation on Testicular and Penile Cancer. This review addresses the main updates to germ cell tumour classification. Major changes include a pathogenetically derived classification using germ cell neoplasia in situ (GCNIS) as a new name for the precursor lesion, and the distinction of prepubertal tumours (non-GCNIS-derived) from postpubertal-type tumours (GCNIS-derived), acknowledging the existence of rare benign prepubertal-type teratomas in the postpubertal testis. Spermatocytic tumour is adopted as a replacement for spermatocytic seminoma, to avoid potential confusion with the unrelated usual seminoma. The spectrum of trophoblastic tumours arising in the setting of testicular germ cell tumour continues to expand, to include epithelioid and placental site trophoblastic tumours analogous to those of the gynaecological tract. Currently, reporting of anaplasia (seminoma or spermatocytic tumour) or immaturity (teratoma) is not required, as these do not have demonstrable prognostic importance. In contrast, overgrowth of a teratomatous component (somatic-type malignancy) and sarcomatous change in spermatocytic tumour indicate more aggressive behaviour, and should be reported.

Tumors of the Testis: Morphologic Features and Molecular Alterations

This article reviews the most frequently encountered tumor of the testis; pure and mixed malignant testicular germ cell tumors (TGCT), with emphasis on adult (postpubertal) TGCTs and their differential diagnoses. We additionally review TGCT in the postchemotherapy setting, and findings to be integrated into the surgical pathology report, including staging of testicular tumors and other problematic issues. The clinical features, gross pathologic findings, key histologic features, common differential diagnoses, the use of immunohistochemistry, and molecular alterations in TGCTs are discussed.

Giant intra-abdominal mature cystic teratoma (dermoid cyst) in an adult man, with male genitourinary tissue including prostatic and penile elements

We describe a case of a giant intra-abdominal mature cystic teratoma in a 36-year-old man, which comprised typical features of differentiated teratoma/dermoid cyst but which contained a macroscopic rudimentary penis, with vasoformative erectile tissue-like structures consistent with corpora cavernosa, as well as scrotal-type skin and prostatic tissue. The genitourinary structures were well formed both grossly and microscopically and sharply demarcated from the rest of the neoplasm, which comprised typical differentiated teratoma, without any other macroscopic foci of organoid differentiation or of other histologic differentiation. The plasticity of the cells of differentiated teratoma, which enables it to undergo multidirectional differentiation, is well recognized, but the factors determining this distinct path of differentiation remain to be established.

Handling and reporting of orchidectomy specimens with testicular cancer: areas of consensus and variation among 25 experts and 225 European pathologists

AIMS

The handling and reporting of testicular tumours is difficult due to their rarity.

METHODS AND RESULTS

A survey developed by the European Network of Uro-Pathology (ENUP) and sent to its members and experts to assess the evaluation of testicular germ cell tumours. Twenty-five experts and 225 ENUP members replied. Areas of disagreement included immaturity in teratomas, reported by 32% of experts but 68% of ENUP. Although the presence of rete testis invasion was reported widely, the distinction between pagetoid and stromal invasion was made by 96% of experts but only 63% of ENUP. Immunohistochemistry was used in more than 50% of cases by 68% of ENUP and 12% of experts. Staging revealed the greatest areas of disagreement. Invasion of the tunica vaginalis without vascular invasion was interpreted as T1 by 52% of experts and 67% of ENUP, but T2 by the remainder. Tumour invading the hilar adipose tissue adjacent to the epididymis without vascular invasion was interpreted as T1: 40% of experts, 43% of ENUP; T2: 36% of experts, 30% of ENUP; and T3: 24% of experts, 27% of ENUP.

CONCLUSIONS

There is remarkable consensus in many areas of testicular pathology. Significant areas of disagreement included staging and reporting of histological types, both of which have the potential to impact on therapy.

Clinical applications of recent molecular advances in urologic malignancies: no longer chasing a "mirage"?

As our understanding of the molecular events leading to the development and progression of genitourologic malignancies, new markers of detection, prognostication, and therapy prediction can be exploited in the management of these prevalent tumors. The current review discusses the recent advances in prostate, bladder, renal, and testicular neoplasms that are pertinent to the anatomic pathologist.

[Giant teratoma of the umbilical cord associated with foetal malformations: a morphological and cytogenetic study]

We report on an unusually large teratoma of the umbilical cord associated with multiple fetal anomalies. At 18 WG, an umbilical cord tumour was discovered by ultrasonography in a 38 year-old woman. A 2680 g female neonate (46, XX) was delivered at 37 WG by caesarean section. During surgery for exomphalos, a complete bowel malrotation, ischemic jejunal stenoses and bowel duplication were discovered. The tumor (2515 g) was a teratoma supplied by collaterals of the umbilical vein. Proliferative index calculated by flow cytometry was less than 10%. Tumor karyotype revealed several numerical anomalies with no structural abnormalities using multi-FISH analysis. Immunostaining for CEA and AFP were observed in endodermic derivatives of the duplication and associated with transient high levels of AFP in the blood. To our knowledge, it is the first case to be reported in the literature where karyotype, multi-FISH and FCM studies were available.

Molecular genetic evidence supporting the neoplastic nature of fibrous stroma in testicular teratoma

Testicular teratoma typically consists of heterogeneous mixtures of diverse epithelial and stromal components. The biological nature and genetic characteristics of the fibrous stroma of testicular teratomas have not been thoroughly investigated. Chromosome 12p abnormalities are the hallmark genetic alterations of germ cell tumors. We studied chromosome 12p abnormalities in the fibrous stroma and other components of pure testicular teratomas from 32 patients using interphase fluorescence in situ hybridization. Overall, 72% (23/32) of pure testicular teratomas had chromosome 12p abnormalities. Isochromosome 12p or 12p overrepresentation independent of isochromosome 12p was detected in the fibrous stroma in 53% (17/32) and 41% (13/32) of cases, respectively. Among the 17 cases positive for isochromosome 12p, 8 (47%) also had 12p overrepresentation. In 31% (10/32) cases, the fibrous stroma showed neither 12p overrepresentation nor isochromosome 12p. Isochromosome 12p and 12p overrepresentation were identified, respectively, in the gastrointestinal-type epithelium of 14/23 (61%) and 15/23 (65%) cases; in the respiratory-type epithelium of 41% (7/17) and 41% (7/17) cases; in the squamous epithelium of 62% (8/13) and 54% (7/13) cases; and in the cartilage of 63% (5/8) and 38% (3/8) cases. Concordant chromosomal 12p abnormalities were observed between the fibrous stroma and epithelial elements of testicular teratomas. Our results indicate that the fibrous stroma of testicular teratomas frequently has genetic abnormalities similar to those of the epithelial components. Concordant chromosome 12p alterations between the fibrous stroma and epithelial elements provide further evidence that both epithelial and fibrous components of teratoma are derived from a common progenitor.

Benign cystic lesions in the testis of children

Cystic lesions in the testis of children are rare and in most cases benign tumors. However, a preoperative diagnostic work-up could contribute to planning the surgical procedure: orchiectomy in the case of potential malignancy or otherwise a testis-sparing approach. In this study we reviewed our recent cases of benign cystic testicular tumors and the corresponding literature. The different entities are presented with details of the diagnostic work-up, pathology and treatment of these lesions. In all presented cases, organ-preserving treatment was performed. This practice is to be recommended in the case of all prepubertal cystic testicular lesions.

Difficult differential diagnoses in testicular pathology

CONTEXT

Although relatively rare, testicular cancer is the most common solid organ malignancy in young men and remains a leading cause of cancer death in this population. Different types of testicular tumors are treated differently, with an overall very high cure rate with proper management. Pathologists must, therefore, be familiar with important diagnostic pitfalls in testicular pathology, particularly those that result in different treatments or prognoses.

OBJECTIVE

To summarize key diagnostic features and useful ancillary tools for the most frequently encountered problems in testicular tumor pathology.

DATA SOURCES

Current texts, PubMed (National Library of Medicine) articles, and archives at Indiana University School of Medicine and Beth Israel Deaconess Medical Center were all reviewed.

CONCLUSIONS

Problematic differential diagnoses include seminoma versus nonseminomatous germ cell tumors, germ cell tumors versus non-germ cell tumors, intratubular germ cell neoplasia versus atypical germ cells with maturation arrest, pseudolymphovascular invasion versus real lymphovascular invasion in germ cell tumors, and macroscopic Sertoli cell nodules versus Sertoli cell tumors. In almost all cases, awareness of the differential diagnostic possibilities based on routine light microscopic features permits application of either additional, directed observations or immunohistochemical studies that lead to an accurate diagnosis.

Squamous cysts arising from segmental renal dysplasia

BACKGROUND

Cystic renal dysplasia is a common developmental abnormality of fetal kidney, featuring disorganized lobar organization, undifferentiated mesenchyma, metaplastic cartilage, persisting immature collecting ducts, and cystic changes. Cystic renal dysplasia can affect the entire kidney or in a segmental fashion. Squamous cysts within the dysplastic kidney, however, are exceedingly rare; only two cases have been reported in the English literature, dating back about 25 years.

CASE REPORT

This report is, to our knowledge, the second to describe this unusual finding and may be viewed as confirmation of the entity. In the two previous cases, squamous cysts arose in a generalized cystic dysplasia background; the one we are reporting instead happened in a case of segmental cystic renal dysplasia.

CONCLUSIONS

We further proved, with fluorescent in situ hybridization (FISH), the negativity of 12p amplification in this lesion, supporting the notion that this lesion is not intrarenal teratomatous in nature.

Testicular epidermoid cysts in children: sonographic characteristics with pathological correlation

BACKGROUND

Testicular epidermoid cyst is a rare benign tumor in children. Although this entity is widely described in adults in literature, there are no large series describing the pathological and radiological findings in children. Knowledge of the sonographic features seen in children may alter surgical treatment.

OBJECTIVE

To describe the specific US characteristics of testicular epidermoid cyst in children and to correlate these findings with pathology.

MATERIALS AND METHODS

All children with pathologically proven epidermoid cyst and preoperative sonograms diagnosed at a single children's hospital between 1978 and 2008 were included. For each child, the medical records, preoperative US and pathological specimens were reviewed and correlated.

RESULTS

Eleven patients (ages 1-17 years old) met our criteria. Nine cysts had characteristic target or onion ring appearances, the youngest patient had a simple cyst-like lesion, one cyst had a heterogeneous appearance, and more than 80% of the cysts presented daughter cysts attached along the periphery of the main cyst.

CONCLUSION

In addition to the commonly described findings of the epidermoid cyst (the target and onion ring appearances), simple cysts and the presence of daughter lesions are newly described findings that point to the diagnosis of this benign entity in children.

Multilocular cystic renal cell carcinoma is a subtype of clear cell renal cell carcinoma

Multilocular cystic renal cell carcinoma is an uncommon low grade renal cell carcinoma with unique morphologic features. Its cytogenetic characteristics have not been fully investigated. Its relationship to typical clear cell renal cell carcinoma is uncertain. We evaluated 19 cases of multilocular cystic renal cell carcinoma diagnosed by strict morphologic criteria using the 2004 WHO classification system. The control group consisted of 19 low grade (Fuhrman grades 1 or 2) clear cell renal cell carcinomas. Chromosome 3p deletion status was determined by dual color interphase fluorescence in situ hybridization analysis. Chromosome 3p deletion was identified in 17 out of 19 (89%) of the clear cell renal cell carcinoma cases and 14 out of 19 (74%) of the multilocular cystic renal cell carcinoma cases, respectively. There was no difference in the status of chromosome 3p deletion between clear cell renal cell carcinoma and multilocular cystic renal cell carcinoma (P=0.40). These results support the concept that multilocular cystic renal cell carcinoma as a subtype of clear cell renal cell carcinoma.

Morphologic, immunohistochemical, and fluorescence in situ hybridization study of ovarian embryonal carcinoma with comparison to solid variant of yolk sac tumor and immature teratoma

The prognosis and therapy for malignant ovarian germ cell tumors including embryonal carcinoma differ from those of other categories of ovarian tumors, making accurate diagnosis imperative for patient care. Because of its rarity, the protein markers and genomic alterations typifying primary ovarian embryonal carcinoma have not been fully characterized. The present study aims to establish a set of sensitive and specific protein markers useful for the diagnosis and delineation of ovarian embryonal carcinoma. Chromosomal 12p anomalies were analyzed by dual-color fluorescence in situ hybridization. In a series of 6 ovarian mixed germ cell tumors with a component of embryonal carcinomas, OCT4, CD30, SOX2, and glypican 3 expressions were analyzed immunohistochemically on formalin-fixed paraffin-embedded tissue specimens. The results were compared to 4 cases of mixed germ cell tumor that were originally mistaken for embryonal carcinoma. OCT4 marked the nuclei of 6 cases, among which 5 cases also showed glypican 3 expression indicative of an admixed yolk sac tumor component. SOX2 was positive in only 3 cases of embryonal carcinoma. In 1 case of mixed germ cell tumor containing embryonal carcinoma, embryoid bodies from a component of polyembryoma were demonstrated to be both OCT4 and CD30 positive. Two cases originally classified as embryonal carcinoma were OCT4 and CD30 negative and showed glypican 3 positivity. They were reclassified as solid variant of yolk sac tumor. Two other cases originally classified as embryonal carcinoma were OCT4 positive and CD30 negative and were classified as immature teratoma with neuroectodermal differentiation based on the immunohistochemical findings as well as morphologic features and were diagnosed as immature teratoma. Chromosome 12p alterations were identified in 5 of 6 cases of embryonal carcinomas. In summary, a panel of immunostains is more useful than a single biomarker in the differential diagnosis of ovarian germ cell tumors. Chromosome 12p fluorescence in situ hybridization combined with OCT4, CD30, and glypican 3 immunostains is useful in confirming the diagnosis of ovarian embryonal carcinoma.

Secondary neoplasms of the urinary system and male genital organs

BACKGROUND AND AIMS

In this review we discuss those secondary tumours involving the urinary system and male genital organs that can pose differential diagnostic difficulties with primary lesions, and highlight morphological and ancillary features that could be helpful in reaching a proper assignment of primary origin.

MATERIALS AND METHODS

Based on MEDLINE database searches all reports of secondary tumours involving the urinary system (kidney and bladder) and male genital organs (prostate, testis and penis) were examined.

RESULTS AND DISCUSSION

Involvement by a secondary tumour occurs either as a metastasis or by direct extension. Among non-genitourinary primary sites, colorectal, pulmonary, skin (melanoma) and breast are the most common contributors. Secondary spread from a genitourinary site primary tumour to another genitourinary organ occurs most frequently between the prostate and urinary bladder, given the intimate topographic proximity of the two. The prognosis is very poor, as the secondary tumour usually occurs in patients with carcinoma in the late stages. Few secondary tumours have distinctive histological and immunohistochemical features, making it difficult to make the appropriate diagnosis. Hence, knowledge of the history and clinical setting are particularly important in these cases.

CONCLUSION

The urinary system and male genital organs are not common sites for secondary tumours. They often go either undiagnosed or misdiagnosed in the clinical follow-up of patients with cancer. Accurate diagnosis is essential because of differing therapeutic approaches compared with a primary neoplasm.

Molecular Pathology of the Genitourinary Tract: Molecular Pathology of Kidney and Testes

With the advent of newer molecular technologies, our knowledge of cellular mechanisms with tumors of the kidney and testis has grown exponentially. Molecular technologies have led to better understanding of interplay between the von Hippel-Lindau gene and angiogenic cytokines in renal cancer and isochromosome 12p in testicular neoplasms. The result has been development of antiangiogenic-targeted therapy within recent years that has become the mainstay treatment for metastatic renal cell cancer. In the near future, classification and diagnosis of renal and testicular tumors through morphologic analysis will be supplemented by molecular information correlating to prognosis and targeted therapy. This article outlines tumor molecular pathology of the kidney and testis encompassing current genomic, epigenomic, and proteonomic findings.

Benign and Malignant Neoplasms of the Testis and Paratesticular Tissue

Benign and malignant tumors of the testes and paratesticular tissues present an interesting spectrum of diagnostic entities often encountered in routine surgical pathology practice. Germ cell tumors are the most common tumors of the testes and, despite a rising incidence, have excellent prognosis because of their radiosensitivity and/or effective chemotherapeutic agents. The proper classification of these tumors aids in the choice of appropriate treatment options. This article reviews benign and malignant neoplastic entities of the testes and paratesticular tissues and illustrates the classic pathologic characteristics. The differential diagnosis, along with ancillary studies, clinical significance, and presentation are discussed also.

[Benign space-occupying cysts in the testis. An overview]

Testicular cysts are increasingly diagnosed in the course of scrotal ultrasound examination. Among other things this is due to the general availability of modern high-resolution ultrasound devices. Benign and malignant diseases with testicular cyst formation need to be differentiated by differential diagnosis and by their aetiology. Benign diseases with cystic space-occupying lesions of the testicle are tubular ectasia of the rete testis, cystic dysplasia, epidermoid cysts, simple intraparenchymatous testicular cysts and cysts of the tunica albuginea. Testicular dermoid cyst was long misleadingly regarded as potentially malignant, but is now classified as benign. On diagnosis of a benign lesion of the testis an organ-conserving surgical therapy or an observational watch-and-wait strategy can be recommended in most cases.

Interphase cytogenetic analysis with centromeric probes for chromosomes 1, 2, 6, 10, and 17 in 11 tumors from a patient with bilateral renal oncocytosis

Renal oncocytosis is characterized by the presence of multiple tumors with oncocytic features, often associated with small clusters of tubule-like structures with oncocytic change. The morphologic features of the oncocytic nodules encompass a spectrum of appearances, with patterns typical of renal oncocytoma or classic chromophobe renal cell carcinoma, as well as 'hybrid' tumors with features resembling both oncocytoma and chromophobe renal cell carcinoma. We utilized interphase cytogenetic methods to study 11 tumors from the kidneys of a 45-year-old woman. The tumors included morphologically classical oncocytomas and 'hybrid' tumors with features reminiscent of chromophobe carcinoma. The kidneys also showed foci of oncocytic change in renal tubules. Fluorescence in situ hybridization was performed with centromeric probes for chromosomes 1, 2, 6, 10, and 17 in each of the 11 tumors to determine whether or not there were losses of the chromosomes that are most frequently lost in chromophobe renal cell carcinomas. Neoplastic nuclei from each tumor were evaluated for the number of hybridization signals and scored according to the percentage of nuclei with one, two, and three or more signals. The normal renal parenchyma surrounding the tumors was used as control tissue. All 11 tumors from this patient with renal oncocytosis showed no loss of any of the chromosomes 1, 2, 6, 10, or 17, a pattern identical to that found in normal control tissues. These observations weigh against the concept that hybrid tumors of oncocytosis are closely related to chromophobe renal cell carcinoma.

Molecular genetic evidence supporting the neoplastic nature of stromal cells in 'fibrosis' after chemotherapy for testicular germ cell tumours

A residual retroperitoneal mass containing only fibrosis and necrosis is present in 40-52% of patients with advanced testicular germ cell tumours after chemotherapy. The biological nature and genetic characteristics of the stromal cells in these residual masses have not been adequately investigated. Laser-microdissected stromal cells from 27 patients who underwent retroperitoneal lymph node dissection after chemotherapy for metastatic testicular germ cell tumour were analysed. Allelic loss in the stromal cells of fibrosis was present at one or more of the ten microsatellite DNA loci examined in 23 (85%) of the cases. Chromosome arm 12p anomalies, the hallmark of germ cell neoplasia, were present in nine (33%) cases. The high frequency of allelic losses and chromosome arm 12p anomalies in the stromal cells from residual retroperitoneal fibrous masses after chemotherapy for testicular germ cell tumours suggests that the stromal cells are derived from the same tumour progenitor cells as the pre-existing metastatic germ cell tumour.

Pseudoneoplastic lesions of the testis and paratesticular structures

Pseudotumors or tumor-like proliferations (non-neoplastic masses) and benign mimickers (non-neoplastic cellular proliferations) are rare in the testis and paratesticular structures. Clinically, these lesions (cysts, ectopic tissues, and vascular, inflammatory, or hyperplastic lesions) are of great interest for the reason that, because of the topography, they may be relevant as differential diagnoses. The purpose of this paper is to present an overview of the pseudoneoplasic entities arising in the testis and paratesticular structures; emphasis is placed on how the practicing pathologist may distinguish benign mimickers and pseudotumors from true neoplasia. These lesions can be classified as macroscopic or microscopic mimickers of neoplasia.