Dermoid cyst of the testis: a study of five postpubertal cases, including a pilomatrixoma-like variant, with evidence supporting its separate classification from mature testicular teratoma

Germ cell neoplasms of the testis: Update for 2022

Germ cell neoplasia in situ (GCNIS) is the precursor of both seminomatous and non-seminomatous germ cell tumors. It consists of distended tubules that may have either intratubular seminoma or intratubular embryonal carcinoma cells. Many invasive non-seminomatous tumors contain a mixture of tumor types, which are reviewed here. Morphology, aided by a panel of immunostains, can determine the presence and percent of embryonal carcinoma, yolk sac tumor, choriocarcinoma, or teratoma in such tumors. Use of immunostains, required for diagnosis in perhaps 25% of testicular neoplasms, is reviewed. Changes of classification in the AJCC (8^th edition) in 2016 are discussed, including the partitioning of two tumor types: the central role of chromosome 12p amplification allows both teratoma and yolk sac tumor to be divided into prepubertal types (lacking amplification) and post-pubertal types. Occasionally, sex cord-stromal tumors, hematolymphoid tumors, or epididymal adenomatoid tumors enter the differential diagnosis of germ cell neoplasms.

Decoding germ cell tumours for clinicians

PURPOSE OF REVIEW

Germ-cell tumours of the testis affect predominantly younger males aged between 15 and 40 years, with nearly 74,500 new cases estimated globally in 2020. Their rarity and the complex morphology, mean that, in nonexpert hands, there is a significant risk of misdiagnosis of both type and staging of these neoplasms.

RECENT FINDINGS

There have been significant changes in the 2016 WHO classification of Testicular tumours that need to be understood by both pathologists and clinicians for streamlining management. Standardised structured reporting guidelines and discussion at the multidisciplinary-team meetings lead to subsequently better health outcomes and patient safety.

SUMMARY

Therefore, communication with high-quality reports and understanding of clinicians of what constitutes an adequate report, is the key to ensure proper management of these patients. We attempt to discuss the key updates and pathological features that influence management and need to be communicated with clarity and precision.

Paratesticular Dermoid Cyst Mimicking a Torsed Supernumerary Testis: A Case Report

Patient: Male, 8-year-old

Final Diagnosis: Dermoid cyst

Symptoms: Pain

Medication: —

Clinical Procedure: Ultrasonography

Specialty: Radiology

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.

Meningothelial Meningioma Component in a Prepubertal Testicular Teratoma

Teratomas are nonseminomatous germ cell tumors composed of elements derived from more than one germinal layers (endoderm, mesoderm, and ectoderm). Malignant transformation of teratoma in the testis is well known; however, benign somatic neoplasm arising in a testicular teratoma is a rare occurrence. We report a case of meningothelial variant of meningioma arising in a pure and mature teratoma of the testis in a 5-year-old boy. Immunohistochemistry was positive for epithelial membrane antigen and vimentin. To our knowledge, this is the first report of meningothelial meningioma in a prepubertal testicular teratoma.

Shadow Cell Differentiation: A Comparative Analysis of Modes of Cell Death with Apoptosis and Epidermal/Trichilemmal Keratinization

Shadow cells are characterized by an eosinophilic cytoplasm and a ghost-like nuclear contour; the cell shape is preserved, in spite of nuclear disappearance. Shadow cell nests (SCNs) are frequently observed in pilomatricoma (PMX), where the transitional cells immediately adjacent to SCNs often have a crescent-shaped nucleus showing fragmentation similar to that of apoptotic bodies. They show nuclear accumulation of beta-catenin and DNA double strand breaks (as revealed by in situ 3′-tailing reaction or immunohistochemistry for single-stranded DNA [ssDNA]), while they are negative for cleaved caspase-3 or cleaved lamin A, suggesting that shadow cell differentiation (SCD) is a caspase-independent programmed cell death. SCD can be differentiated from epidermal keratinization (EK) and trichilemmal keratinization (TK) based on the expression pattern of beta-catenin, ssDNA, and caspase-14/CD138. SCD is observed not only in PMX, but also sometimes in basal cell carcinomas, gonadal teratomas, and various extra-cutaneous carcinomas. In particular, SCNs are found in 24$ of endometrial adenoacanthoma and are derived from squamoid morules. This establishes a link between basaloid cells in PMX and squamoid morules in endometrial adenoacanthomas as common precursors of shadow cells. Overall, it is suggested that SCD is different from, but partly similar to, apoptosis and that SCD and EK/TK should be differentiated from the standpoint of cell death/differentiation.

Epidemiologic study of 230 cases of testicular/paratesticular tumors or masses: 15-year experience of a single center

PURPOSE

This study retrospectively investigated the cases of testicular tumors/masses treated in our center from 2002 to 2017 and analyzed their epidemiologic features.

METHODS

Data were collected by searching our center's database using "testicular tumor" or "testicular mass" as keywords. Patients not operated in our hospital were excluded. Preoperative serum alpha-fetoprotein (AFP) levels were reviewed in germ cell tumor (GCT) cases and analyzed to predict malignancy in various age groups.

RESULTS

In total, 230 cases were identified: 151 were benign (78 in the left, 72 in the right, and 1 bilateral) with 3.63years mean age during the operation, and 79 were malignant (42 in the left, 36 in the right, and 1 bilateral) with 2.21years mean age during the operation. Main pathological diagnoses were mature teratoma (92, 40.00%), yolk sac tumor (53, 23.04%), dermoid cyst (23, 10.00%), embryonic carcinoma (15, 6.53%), immature teratoma (14, 6.09%), benign cyst (8, 3.48%), Leydig cell tumor (6, 2.61%), and paratesticular rhabdomyosarcoma (5, 2.17%). All GCT cases with AFP >1000ng/ml, >100ng/ml, >20ng/ml were malignant in <7-, 7-9-, and ≥10-month-old groups, respectively.

CONCLUSIONS

Radical inguinal orchiectomy without biopsy is suggested in 7-9- and ≥10-month-old cases with AFP >100ng/ml and >20ng/ml, respectively.

TYPE OF STUDY

Retrospective Study.

LEVEL OF EVIDENCE

Level III-IV.

Basal Cell Carcinoma With Matrical Differentiation: Clinicopathologic, Immunohistochemical, and Molecular Biological Study of 22 Cases

Basal cell carcinoma (BCC) with matrical differentiation is a fairly rare neoplasm, with about 30 cases documented mainly as isolated case reports. We studied a series of this neoplasm, including cases with an atypical matrical component, a hitherto unreported feature. Lesions coded as BCC with matrical differentiation were reviewed; 22 cases were included. Immunohistochemical studies were performed using antibodies against BerEp4, β-catenin, and epithelial membrane antigen (EMA). Molecular genetic studies using Ion AmpliSeq Cancer Hotspot Panel v2 by massively parallel sequencing on Ion Torrent PGM were performed in 2 cases with an atypical matrical component (1 was previously subjected to microdissection to sample the matrical and BCC areas separately). There were 13 male and 9 female patients, ranging in age from 41 to 89 years. Microscopically, all lesions manifested at least 2 components, a BCC area (follicular germinative differentiation) and areas with matrical differentiation. A BCC component dominated in 14 cases, whereas a matrical component dominated in 4 cases. Matrical differentiation was recognized as matrical/supramatrical cells (n=21), shadow cells (n=21), bright red trichohyaline granules (n=18), and blue-gray corneocytes (n=18). In 2 cases, matrical areas manifested cytologic atypia, and a third case exhibited an infiltrative growth pattern, with the tumor metastasizing to a lymph node. BerEP4 labeled the follicular germinative cells, whereas it was markedly reduced or negative in matrical areas. The reverse pattern was seen with β-catenin. EMA was negative in BCC areas but stained a proportion of matrical/supramatrical cells. Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components. It is concluded that matrical differentiation in BCC in most cases occurs as multiple foci. Rare neoplasms manifest atypia in the matrical areas. Immunohistochemical analysis for BerEP4, EMA, and β-catenin can be helpful in limited biopsy specimens. From a molecular biological prospective, BCC and matrical components appear to share some of the gene mutations but have differences in others, but this observation must be validated in a large series.

Perspectives in Pediatric Pathology, Chapter 25. Testicular and Paratesticular Tumors in the Pediatric Age Group

Testicular tumors in the prepubertal age are relatively rare, representing only 9.4% of the total testicular and paratesticular specimens from a 20-year review performed at a large pediatric hospital [ 1 ]. They account for 1% to 2% of all solid tumors in the pediatric age group, with an annual incidence between 0.5/100 000 and 2/100 000 boys according to Coppes et al [ 2 ] and data from the Prepubertal Testicular Tumor Registry [ 3 ]. Similar to other neoplasms afflicting children, a bimodal age distribution is observed. The first peak is between birth and 3 years of age, and a second one occurs at the onset of puberty, extending to the fourth decade. Reports on their frequency vary because some investigators include the adolescent period, while others do not [ 4 ]. The vast majority of testicular tumors are germ cell neoplasms, accounting for 95% across all ages [ 5 ]. In children, germ cell tumors also predominate, representing 71% of all testicular neoplasms. These include yolk sac tumors (49%), teratomas (13%), seminomas and mixed germ cell tumors (9%), and sex-cord stromal tumors (29%). Malignant potential is significantly lower (less than 70%) in the pediatric age group compared to adults (90%) [ 6 ]. According to Pohl et al, 74% of prepubertal testicular tumors are benign [ 7 ].

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.

Large Sublingual Dermoid Cyst: A Case of Mandibular Prognathism

Dermoid cysts are unusual neoplasms and can occur in every part of the human body. They represent only 6.9% of all dermoid cysts in the head and neck region; in the oral cavity, the incidence is low, approximately 1.6% of all dermoid cysts. Our aim is to present an unusual case of a large sublingual dermoid cyst with mandibular prognathism caused by cyst growth. We reported a case of a large sublingual dermoid cyst in an 8-year-old female patient. A bibliographic research from 1937 to 2013 is reviewed and we found only three cases of mandibular deformity, of which only one was a dermoid cyst of the floor of the mouth. Removal of dermoid cysts of the floor of the mouth should be completed as early as detected, especially in newborns and infants when osseous growth abnormalities could result if removal is delayed.

Benign scrotal masses in children - some new lessons learned

INTRODUCTION

A preponderance of benign intratesticular masses in pre-pubertal males encourages testicular-sparing surgery (TSS).

OBJECTIVE

To review outcome of benign testicular lumps in children managed at a tertiary pediatric center more than 7.5years.

METHODS

A retrospective review of pediatric benign testicular lesions from January 2008 to June 2015 was performed.

RESULTS

There were twelve benign intratesticular tumors. Of these, 11 were in pre-pubertal males; comprising four teratomas, two epidermoid cysts, one dermoid cyst, two cases of Leydig cell hyperplasia, one cystic dysplasia of the rete testis and one large simple intratesticular cyst. We illustrate a case of Leydig cell hyperplasia presenting with precocious puberty limited to the ipsilateral hemi-scrotum. TSS was attempted in all 11 pre-pubertal cases, but successfully performed in seven. TSS was possible for a large testicular cyst seemingly replacing the entire testis, with evidence that the testis reconstituted itself after surgery. Recurrence of an epidermoid cysts reported.

CONCLUSION

For the first time in the literature, this series reports Leydig cell hyperplasia presenting with ipsilateral hemi-scrotal changes of precocious puberty; shows evidence that the testis reconstitutes itself after TSS for a large cyst; and reports recurrence of an epidermoid cyst after TSS.

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.

Pilomatrixoma-like testicular tumour without teratomatous elements

A 40-year-old man presented to us with infertility. During scrotal ultrasonography, a heterogeneous nodular mass was seen in the right testicle. Surprisingly, histopathological examination revealed shadow cells, which are the characteristic feature of pilomatrixomas.

Scrotal dermoid extending to the posterior urethra through a corpus cavernosum in a child

A 3-year-old boy presented with an asymptomatic intertesticular mass increasing in size. Plasma tumor markers (α-fetoprotein and β-human chorionic gonadotrophin) were negative. The mass had a pattern similar to testicular parenchyma but no discernable blood flow on scrotal Doppler ultrasound. Magnetic resonance imaging scan showed that it reached the posterior urethra after passing through the right corpus cavernosum with a progressive tapering extending into the pelvis. The mass was excised surgically and histologically found to be consistent with a dermoid cyst. Such rare benign lesions should be considered in the differential diagnosis of painless scrotal masses in children. Its anatomy was accurately defined by magnetic resonance imaging and was essential to minimize the risk to adjacent structures.

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.

Mature cystic teratoma (dermoid cyst) in the sylvian fissure: a case report and review of the literature

Mature cystic teratoma (dermoid cyst) inside the Sylvian fissure is rare. A 14-year-old boy presented with 2 episodes of generalized tonic-clonic seizures. Using a fat-suppressed, T1-weighted sequence, magnetic resonance imaging revealed a hypointense nonenhancing mass in the left Sylvian fissure. He underwent left pterional craniotomy for total tumor resection. The pathological diagnosis was mature cystic teratoma (dermoid cyst). Headache and seizures are the leading symptoms. Cyst rupture causes inflammation of cholesterol crystals, and the cyst contents may cause seizure. Surgical resection is the treatment of choice, but radical resection is not advised if critical neurovascular structure can be injured.

Testing testes: problems and recent advances in the diagnosis of testicular tumours and implications for treatment

The low incidence of testicular tumours and the fact that they show an extremely high diversity means that they may be poorly understood. Knowledge of the range of tumours and the differences in treatment available is essential for appropriate management. The advent of cisplatin chemotherapy and the exquisite sensitivity of seminoma to radiotherapy have resulted in excellent cure rates. Nevertheless, research has continued unabated, particularly to understand the molecular basis of germ cell tumours and why certain tumours are recalcitrant to treatment. This overview is an attempt to demystify areas of confusion and highlight areas of current interest in testicular pathology and oncology.

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.

Testicular Tumors—Some New and a Few Perennial Problems

The histopathology of testicular tumors is presented, emphasizing new, unusual, or underemphasized aspects. Within the category of seminoma of the usual type, the recent literature has drawn attention to the presence in occasional tumors of solid or hollow tubules or spaces of varying sizes and shape that may result in cribriform or microcystic patterns, causing potential confusion with other neoplasms, most notably Sertoli cell tumor or yolk sac tumor. Although regions of typical neoplasia and awareness of this phenomenon usually will be diagnostic, immunohistochemistry may play a role in excluding Sertoli cell tumor or yolk sac tumor. Although immunohistochemistry can play an undoubted helpful role in this and selected other areas of testicular tumor evaluation, careful evaluation of the gross and routine microscopic features will solve the vast majority of diagnostic problems. An excellent review of immunohistochemistry in this area by R. E. Emerson, MD, and T. M. Ulbright, MD, is cited herein. Spermatocytic seminoma remains a crucial pitfall in diagnosis, and the pathologist must always be alert to the possible diagnosis when looking at a seminomatous neoplasm, particularly in an older patient, although about one third of these tumors occur in the usual seminoma age range. The embryonal carcinoma has a great diversity of patterns, which are briefly noted. The enigmatic and picturesque tumor, polyembryoma, which virtually never occurs in pure form but may be a confusing component of a variety of mixed germ cell tumors, is discussed and illustrated. The phenomenon of burnt-out germ cell neoplasia is also briefly noted and an excellent recent contribution is referred to. Within the sex cord–stromal family of neoplasms, recent contributions and elaborations of unusual morphologic features of Leydig cell tumors and Sertoli cell tumors are presented. Within the Leydig cell family, cyst formation, adipose metaplasia, calcification or ossification, and spindle cell patterns may be particularly confusing, and in the Sertoli cell family, a great array of patterns caused by differing admixtures of tubular, solid, and stromal components occur. The peculiar lesion, intratubular large cell hyalinizing Sertoli cell tumor, of young boys with Peutz-Jeghers syndrome, is briefly discussed. Some of the problems in the family of hematopoietic neoplasms are reviewed, these processes posing diverse problems in differential diagnosis and their correct recognition having crucial therapeutic implications. Although secondary tumors to the testis have not received the same attention in the literature as the similar phenomenon in the female gonad, remarkable examples of testicular spread of diverse neoplasms, usually carcinoma but rarely melanoma, are seen, and the pathologist should be alert to this possibility, particularly when examining an unusual morphology in an older patient. Finally, a few comments are made on the common paratesticular neoplasm, the adenomatoid tumor, highlighting its varied patterns and recent description of some of the issues that may arise when they undergo total or subtotal infarction.

The most common, clinically significant misdiagnoses in testicular tumor pathology, and how to avoid them

Testicular tumors are both increasing in frequency and disproportionately occur in young men; furthermore, different forms of neoplasm require different treatments. These considerations make the accurate diagnosis of testicular tumors especially important. Many of the critical distinctions involve the differentiation of seminoma from one or more potential mimics because seminoma is not only the most common testicular neoplasm but it is also the only malignant testicular tumor that is commonly treated with radiation, which is ineffective in other malignancies of the testis. For the most part, accurate diagnosis can be achieved by careful light microscopic evaluation, although appropriate immunostains can provide diagnostic assistance if doubt persists. This article discusses a number of clinically important differential diagnoses in the testis that are common sources of misinterpretations. These include: seminoma versus embryonal carcinoma, seminoma versus yolk sac tumor, seminoma versus Sertoli cell tumor, seminoma with syncytiotrophoblast cells versus choriocarcinoma, granulomatous seminoma versus granulomatous orchitis, intertubular seminoma versus orchitis, lymphoma versus seminoma or embryonal carcinoma, dermoid cyst versus teratoma, scar versus regressed germ cell tumor, and "anaplastic" spermatocytic seminoma versus usual seminoma or embryonal carcinoma.

Pathology of germ cell tumors of the testis

BACKGROUND

An increasing incidence of testis tumors has been noted over the second half of the 20th century. Congenital malformation of the male genitalia, prenatal risk factors, nonspecific and specific exposures in adulthood, and male infertility have all been associated with the etiology of germ cell tumors.

METHODS

The histologic classification, pathology, and current concepts of testicular germ cell tumors are reviewed.

RESULTS

Germ cell tumors occur at all ages. The tumors are identified as pure form (those of one histologic type) and mixed form (more than one histologic type). Over half of germ cell tumors consist of more than one cell type, requiring appropriate sampling for the correct diagnosis and correlation with the serum tumor markers. Burned-out germ cell tumors may occur in patients with metastatic disease with no gross evidence of a testicular tumor.

CONCLUSIONS

Appropriate management of testis tumors relies on accurate pathology and classification of these tumors.

An overview of testicular germ cell tumors

CONTEXT

More than 90% of testicular neoplasms originate from germ cells. Testicular germ cell tumors (GCTs) are a heterogeneous group of neoplasms with diverse histopathology and clinical behavior.

OBJECTIVE

To help the readers distinguish various subtypes of GCTs, to highlight the clinical manifestations and pathologic features of these tumors, and to review several newly developed immunohistochemical markers for GCTs.

DATA SOURCES

Review of the pertinent literature and our experience.

CONCLUSIONS

The etiology of GCTs is largely unknown. Cytogenetic studies suggest a different pathogenesis for each group of infantile/prepubertal GCTs, postpubertal GCTs, and spermatocytic seminoma. Unclassified intratubular germ cell neoplasia is the precursor of all GCTs, excluding spermatocytic seminoma and infantile/prepubertal GCTs. Seminoma, the most common GCT in adults, does not occur before 5 years of age. Spermatocytic seminoma, a tumor of elderly men, typically has an indolent clinical behavior, but rarely it undergoes sarcomatous transformation associated with an aggressive behavior. Embryonal carcinoma is the most common component in mixed GCTs. Eighty percent or more of embryonal carcinoma component and vascular invasion are recognized predictors of occult metastasis for clinical stage I mixed GCTs. Most patients with prepubertal yolk sac tumor, the most common pediatric GCT, have stage I disease at presentation. Most choriocarcinomas present with metastatic symptoms because of the propensity for rapid hematogenous dissemination. Teratomas in children regardless of maturity and dermoid cysts in adults are benign; in contrast, teratomas in adults have a malignant behavior. With appropriate therapy, the majority of testicular GCTs are curable.

Case series: Adult testicular dermoid tumours – mature teratoma or pre-pubertal teratoma?

Adult testicular dermoid tumours are rare tumours with no reported potential for recurrent or metastatic spread. Despite this they are currently classified as mature teratoma and managed as if they have equivalent malignant potential. This report describes two cases of adult mature teratoma of dermoid type and questions the classification and pathogenesis of this disease. In one of the cases there was a clear history of a testicular lump arising pre-pubertally, raising the possibility that some adult dermoid tumours may in fact be pre-pubertal teratomas that have persisted into adulthood. Classification as a mature teratoma carries with it a follow-up regimen that includes numerous radiological investigations with their attendant radiation exposure. A positive histological diagnosis and separate classification of adult dermoid tumours would allay clinical fears of recurrence and metastasis and negate the need for repeated radiological investigations.

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

PURPOSE

The distinction of epidermoid cyst of the testis from teratoma is of critical importance because the former is benign and the latter is a malignant tumor that may have associated metastasis of either teratomatous or non-teratomatous germ cell tumor types. Chromosome 12p abnormalities are seen in the vast majority of testicular germ cell tumors of adults and are present in all histologic subtypes. In this study, we investigated the clinical utility of interphase fluorescence in situ hybridization (FISH) analysis of chromosome 12p abnormalities for distinguishing epidermoid cysts of the testis from pure mature teratoma.

EXPERIMENTAL DESIGN

Sixteen testicular epidermoid cysts and 17 testicular teratomas were investigated for isochromosome 12p [i(12p)] and 12p overrepresentation using interphase FISH analysis.

RESULTS

Neither i(12p) nor 12p overrepresentation were observed in 16 epidermoid cyst cases, whereas i(12p) was detected in 76% of teratomas and 12p overrepresentation was identified in 29% of teratomas. Overall, 88% of testicular teratomas had chromosome 12p abnormalities.

CONCLUSIONS

FISH identification of i(12p) and/or 12p overrepresentation in routinely processed surgical specimens is a useful ancillary diagnostic tool in distinguishing testicular epidermoid cysts from teratoma.

A 7-Year History of an Intratesticular Mass: Patient Description and Review of the Literature about Dermoid Cysts of the Testis

A dermoid cyst is a particular form of a cystic teratoma. In the testis, it is very rare, with only a few cases reported in world literature. A 19-year-old patient come to our attention with a 7-year history of an intratesticular cystic mass. Sonography showed a large hypoechoic solid mass. The tumour markers alpha-fetoprotein, beta-human chorionic gondatotrophin, and lactate dehydrogenase were negative. Chest X-ray was negative. He underwent surgical exploration of the right testis and enucleation of the mass with testis preservation. At 14 month of follow-up, the patient had no complications and no recurrence of the lesion. Surgical enucleation is the treatment of choice in consideration of hormonal, psychological, and reproductive aspects. Orchiectomy should have been the treatment of choice, if the mass had substituted all testicular parenchyma and if there had been some malignant transformations.

Huge epidermoid cyst of the spermatic cord in an adult patient

Tumors arising in the spermatic cord are uncommon and form a heterogeneous group of neoplasms. A variety of both benign and malignant lesions have been demonstrated. Benign tumors represent 80% of the total, but unfortunately clinical and sonographic features are not specific and they cannot safely differentiate a teratomatous or a malignant neoplasm from benign tumors. We report a case of a huge epidermoid cyst of the spermatic cord in an adult patient confirmed after local excision. The etiology, differential diagnosis, and management alternatives are discussed.

Germ cell tumors of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues

Gonadal germ cell tumors continue to be the cause of diverse, diagnostically challenging issues for the pathologist, and their correct resolution often has major important therapeutic and prognostic implications. They are academically interesting because of the biological diversity exhibited in the two gonads and variation in frequency of certain neoplasms. The most dramatic examples of the latter are the frequency of dermoid cyst in the ovary compared to the testis and the reverse pertaining to embryonal carcinoma. Within the teratoma group, there is strong evidence that ovarian and prepubertal testicular teratomas are derived from benign germ cells, a pathogenesis that likely applies also to the rare dermoid cysts and uncommon epidermoid cysts of the testis. In contrast, postpubertal testicular teratomas derive from malignant germ cells, specifically representing differentiation within a preexistent nonteratomatous cancer. As expected, given the foregoing, teratomas in boys are clinically benign, whereas in postpubertal males they are malignant, independent of their degree of immaturity. On the other hand, immaturity is an important finding in ovarian teratomas, irrespective of age, although its significance in children has recently been challenged. It is usually recognized on the basis of embryonic-appearing neuroepithelium, which shows mitotic activity and apoptosis in contrast to differentiated neuroepithelial tissues, which may occur in mature ovarian teratomas. Rarely it is based on the presence of cellular, mitotically active glial tissue. Fetal-type tissues alone are not sufficient for a diagnosis of immature teratoma. Further differences between the teratomatous tumors in the two gonads are the relative frequency of monodermal teratomas in the ovary in contrast to the testis, where only one subset, carcinoids, is seen with any frequency. When uncommon somatic-type malignancies (usually squamous cell carcinoma) occur in mature cystic teratomas of the ovary, this is a de novo form of malignant transformation; similar tumors in the testis, a very rare event, represent overgrowth of teratomatous elements that originated from malignant, nonteratomatous germ cell tumors and, therefore, had previously undergone malignant transformation. Germinomas may have several unusual features in each gonad; these include microcystic arrangements that suggest yolk sac tumor, tubular patterns that mimic Sertoli cell tumor, apparent increased cytological atypia that causes concern for embryonal carcinoma, and prominent syncytiotrophoblast giant cells that suggest choriocarcinoma. Awareness of these variants, good technical preparations, the retained typical cytological features of germinoma cells, and the judicious use of tailored panels of immunohistochemical stains resolve these dilemmas in virtually all instances. Two aspects of germinomas are unique to the testis. Firstly, intertubular growth of small seminomas may cause them to be overlooked. Secondly, the distinctive spermatocytic seminoma occurs only in the testis. A newly recognized aspect of this tumor is the propensity for some to be relatively monomorphic, making them apt to be mistaken for usual seminoma or embryonal carcinoma, although the characteristic polymorphic appearance in some foci, absence of intratubular germ cell neoplasia, unclassified type, and immunohistochemical stains should prevent this error. Cytoplasmic membrane immunoreactivity for placental alkaline phosphatase and CD117, with usual negativity for AE1/AE3 cytokeratins, is helpful in the diagnosis of germinoma. The recently described marker, OCT3/4, a nuclear transcription factor, is especially helpful in the differential of germinoma and embryonal carcinoma with other neoplasms. Yolk sac tumor continues to be confused occasionally with clear cell carcinoma of the ovary. Glandular ('endometrioid-like') yolk sac tumors mimic endometrioid carcinomas; predominant or pure hepatoid yolk sac tumors cause concern for metastatic hepatocellular carcinoma or, in the ovary, primary hepatoid carcinoma, and solid patterns, especially in limited samplings, may be misinterpreted as germinoma. The usually younger age of patients with yolk sac tumors helps with the differential considerations with the nongerm cell tumors, as do other clinical and microscopic features and selected immunohistochemical stains. Choriocarcinoma is rare in both gonads, and those in the ovary must be distinguished from metastatic tumors of placental origin. Syncytiotrophoblast cells alone, admixed with other forms of germ cell tumor, still are confused with choriocarcinoma, but this phenomenon, which is much more frequent than choriocarcinoma, lacks the plexiform arrangement of different trophoblast cell types that typifies the latter. Mixed germ cell tumors (which may show almost any combination of components) are common in the testis but rare in the ovary. A separately categorized, rare form of mixed germ cell tumor seen in both gonads is the polyembryoma. It is perhaps the most photogenic of all gonadal germ cell tumors and is also intriguing because of its distinctive, organized arrangement of yolk sac tumor and embryonal carcinoma elements and recapitulation of very early embryonic development, even to the extent of having in its fundamental unit, the embryoid body, a miniature yolk sac, and amniotic cavity. These tumors, which are constituted by innumerable embryoid bodies, almost always contain teratomatous glands in minor amounts, and one way of viewing the polyembryoma is to consider it the most immature form of teratoma. Embryoid bodies are also common as a minor component of many mixed germ cell tumors, particularly in the testis, and the diffuse embryoma is another variant that has a particular arrangement of yolk sac tumor and embryonal carcinoma elements. Regression of gonadal germ cell tumors is a phenomenon restricted to the testis, for unknown reasons. These so-called 'burnt-out' germ cell tumors can be recognized by a distinctive constellation of findings, including sometimes minor foci of residual recognizable germ cell neoplasia, a well-defined zone of scarring (often having residual ghost tubules), associated lymphoplasmacytic infiltrate, intratubular calcification and, in about 50%, of in situ germ cell neoplasia.

Gonadal teratomas: a review and speculation

Teratomas of the ovary and testis are confusing because, despite histologic similarities, they exhibit different biologic behaviors, depending mostly on the site of occurrence and the age of the patient. Thus, most ovarian teratomas are benign, and most testicular teratomas are malignant, with the exception of those occurring in children. These general statements, however, do not hold true for ovarian teratomas that are "immature" or exhibit "malignant transformation" and for dermoid and epidermoid cysts of the testis, categories of ovarian and testicular teratomas that are malignant and benign, respectively. This review concentrates on some of the "newer" observations concerning these interesting and confusing neoplasms, including diagnostically deceptive patterns. It is the author's opinion that much of the confusion regarding gonadal teratomas can be clarified by the concept that the usual ovarian teratoma derives from a benign germ cell in a parthenogenetic-like fashion, whereas the typical postpubertal testicular example derives from a malignant germ cell, mostly after evolution of that originally malignant cell to an invasive germ cell tumor (ie, embryonal carcinoma, yolk sac tumor, etc). The postpubertal testicular teratomas can therefore be thought of as an end-stage pattern of differentiation of a malignant germ cell tumor. The pediatric testicular teratomas, as well as dermoid and epidermoid cysts of the testis, however, must derive from benign germ cells, in a fashion similar to most ovarian teratomas. The teratomatous components of mixed germ cell tumors of the ovary, on the other hand, likely have a pathogenesis similar to that of postpubertal testicular teratomas.

Primary mucinous tumors of the testis and paratestis: a report of nine cases

Ovarian-type surface epithelial tumors are rare in the testis and paratestis, with most reported examples being serous. There is little information on mucinous tumors, nine of which are described in this report, applying criteria and terminology used in the ovary. The patients were 44-69 years of age (median 64 years) and presented with masses in the testis (four) or paratestis (five). Eight tumors were cystic (median size, 3.5 cm) and contained gelatinous material; one (a paratesticular carcinoma) appeared as thickening of the tunica vaginalis. Two were classified as mucinous cystadenomas (both paratesticular), six as purely or predominantly borderline tumors (four, testis; two, paratestis; one had intraepithelial carcinoma and one microinvasive carcinoma) and one (paratestis) as mucinous carcinoma. The cystadenomas were composed of endocervical-like cells, but intestinal-like cells typified the borderline tumors and carcinomas. Cyst rupture with mucin dissection into the stroma, inflammation, and dystrophic calcification with ossification were common. No tumor was associated with intratubular germ cell neoplasia, unclassified type or with teratomatous elements. One patient with carcinoma died shortly after presentation with peritoneal spread; autopsy disclosed no other potential primary site. The follow-up (1.8-12 years) in all other cases was uneventful. Mucinous tumors of the testis and paratestis resemble their ovarian counterparts, exhibiting the same morphologic spectrum, from benign to borderline to malignant, and having both endocervical-like and intestinal features. These tumors may derive from mesothelium by the process of mullerian neometaplasia, from mullerian remnants or from the mucinous epithelium of a teratoma. The older age of the patients, lack of nonmucinous elements, and absence of intratubular germ cell neoplasia, unclassified type suggest that, if of teratomatous origin, the teratoma is different from the usual type. Clinical features are important to exclude metastasis, particularly in cases of carcinoma and, to a lesser extent, in tumors of borderline type.

Molecular evidence supporting the neoplastic nature of some epidermoid cysts of the testis

CONTEXT

Loss of heterozygosity (LOH) on chromosomes 9p and 12q is common in germ cell tumors of the testis. Loss of heterozygosity of 17p13 has also been demonstrated in germ cell tumors. The incidence of LOH in epidermoid cysts, a possible special form of teratoma, has not been previously determined.

OBJECTIVE

To determine the frequency of LOH in epidermoid cysts.

DESIGN

Eight testicular epidermoid cysts and surrounding parenchyma were microdissected from formalin-fixed, paraffin-embedded tissue, and the genomic DNA was extracted using proteinase K. Polymerase chain reaction analysis targeted regions on chromosome 9p21 (D9S177 and D9S161 loci), chromosome 12q22 (D12S1051 locus), and chromosome 17p13 (TP53 locus). Gel electrophoresis followed by autoradiography was used to detect LOH.

RESULTS

All 8 of the epidermoid cysts were informative at a minimum of 1 of 4 loci. Three demonstrated LOH. In 2 tumors, LOH occurred on chromosome 9, and the third tumor demonstrated LOH on chromosome 12. Loss of heterozygosity on chromosome 17p13 was not present in any of the tumors.

CONCLUSIONS

Epidermoid cysts harbor allelic loss at some of the same loci identified in malignant testicular germ cell tumors. Our findings support that some examples of epidermoid cysts are neoplastic, although their low frequency of LOH also supports that they are genetically different from malignant germ cell tumors.

Mucinous cystadenoma of the testis

A 35-year-old man complained of a painless enlargement of the right testis. Imaging diagnostic procedures demonstrated a multiloculated cystic tumor, 9 cm in maximal diameter, in the right testis with hydrocele. Orchidectomy specimen showed that the tumor was confined within the testis and separated from the epididymis. The locules of the tumor were lined by single-layered columnar epithelium, intermingled with MUC2 immunopositive goblet and chromogranin-A immunopositive neuroendocrine cells, exhibiting intestinal differentiation. No ciliated cell, teratomatous element or intratubular germ cell neoplasia were seen. Channels of rete testis were compressed peripherally by the tumor but there was no connection with the tumor locules. The tumor was diagnosed as mucinous cystadenoma of the testis. This seems to be the first published case of benign mucinous cystadenoma occurring within the testis. This intratesticular tumor with intestinal differentiation may represent a benign monodermal teratoma.