Testicular microlithiasis as a familial risk factor for testicular germ cell tumour

Histological Features of Sporadic and Familial Testicular Germ Cell Tumors Compared and Analysis of Age-Related Changes of Histology

Simple Summary

Testicular germ cell tumors (TGCT) are highly heritable, and earlier studies reported a higher prevalence of certain microscopic features in familial cases compared with sporadic cases. Reasoning by analogy relative to different causal genes for different histologic subtypes of familial kidney cancer, we searched for etiologically informative histopathology associations in familial testicular germ cell cancer. We conducted a detailed, blinded pathology review of familial and sporadic TGCT cases to investigate whether we could identify differences between these two patient subsets and to study the effect of age at diagnosis on histologic features in both groups combined. Our results show no specific histologic differences between familial and sporadic TGCTs. However, we observed histologic features that varied with age at diagnosis among the two groups combined. Thus, our results suggest that there are no histological differences between familial and sporadic TGCT that might identify genetically distinct disease subsets.

Abstract

This study aimed to compare histological features of familial and sporadic testicular germ cell tumors (TGCTs) and surrounding parenchyma, since discriminating features might be etiologically relevant and clinically useful. The study of parenchyma was prompted by reports claiming a higher prevalence of testicular microlithiasis in familial cases. Histological features of TGCTs and surrounding parenchyma of 296 sporadic and 305 familial cases were compared. For each case, one representative hematoxylin and eosin-stained slide was available. Slides were independently scored by two expert pathologists using a semi-quantitative data abstract. Discrepancies were resolved by consensus. A logistic regression model was used to assess the ability to discriminate between sporadic and familial GCT. The histological composition of a tumor, amount of lymphocytic infiltration, amount of germ cell neoplasia in situ (GCNIS), and presence of testicular microlithiasis (TM) did not discriminate between sporadic and familial GCT (area under the curve 0.56, 95%CI 0.51–0.61). Novel observations included increasing lymphocytic infiltration and decreasing GCNIS and TM with increasing age at diagnosis. The presence of tubules with infiltrating lymphocytes was mainly associated with pure seminomas and nonseminomas with a seminoma component. Among seminomas, tubules with infiltrating lymphocytes decreased with increasing age. No discernable differences between sporadic and familial TGCTs were found. The age-related changes in the tumors and surrounding parenchyma in these groups combined are consistent with a host response building up over time predominantly affecting seminomas, the seminoma-component of nonseminomas and GCNIS. TM may gradually dissolve with age. Our hypothesis that histological differences between sporadic and familial TGCT might identify genetically distinct disease subsets was not supported.

Incidence characteristics of testicular microlithiasis and its association with risk of primary testicular tumors in children: a systematic review and meta-analysis

BACKGROUND

To systematically evaluate the incidence characteristics of testicular microlithiasis (TM) in children and its association with primary testicular tumors (PTT).

METHODS

A systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. A priori protocol was registered in the PROSPERO database (CRD42018111119), and a literature search of all relevant studies published until February 2019 was performed. Prospective, retrospective cohort, or cross-sectional studies containing ultrasonography (US) data on the incidence of TM or the association between TM and PTT were eligible for inclusion.

RESULTS

Of the 102 identified articles, 18 studies involving 58,195 children were included in the final analysis. The overall incidence of TM in children with additional risk factors for PTT was 2.7%. In children, the proportion of left TM in unilateral cases was 55.7%, the frequency of bilateral TM was 69.0%, and proportion of classic TM was 71.8% [95% confidence interval (CI) 62.4-81.1%, P = 0.0, I² = 0.0%]. About 93.5% of TM remained unchanged, and newly detected PTT rate was very low (4/296) during follow-up. The overall risk ratio of TM in children with a concurrent diagnosis of PTT was 15.46 (95% CI 6.93-34.47, P < 0.00001).

CONCLUSIONS

The incidence of TM in children is highly variable. Nonetheless, TM is usually bilateral, of the classic type, and remains stable or unchanged at follow-up. Pediatric patients with TM and contributing factors for PTT have an increased risk for PTT; however, there is no evidence to support mandatory US surveillance of children with TM.

Genes associated with testicular germ cell tumors and testicular dysgenesis in patients with testicular microlithiasis

Testicular microlithiasis (TM) is one of the symptoms of testicular dysgenesis syndrome (TDS). TM is particularly interesting as an informative marker of testicular germ cell tumors (TGCTs). KIT ligand gene (KITLG), BCL2 antagonist/killer 1 (BAK1), and sprouty RTK signaling antagonist 4 (SPRY4) genes are associated with a high risk of TGCTs, whereas bone morphogenetic protein 7 gene (BMP7), transforming growth factor beta receptor 3 gene (TGFBR3), and homeobox D cluster genes (HOXD) are related to TDS. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, we investigated allele and genotype frequencies for KITLG (rs995030, rs1508595), SPRY4 (rs4624820, rs6897876), BAK1 (rs210138), BMP7 (rs388286), TGFBR3 (rs12082710), and HOXD (rs17198432) in 142 TGCT patients, 137 TM patients, and 153 fertile men (control group). We found significant differences in the KITLG GG_rs995030 genotype in TM (P = 0.01) and TGCT patients (P = 0.0005) compared with the control. We also revealed strong associations between KITLG_rs1508595 and TM (G allele, P = 0.003; GG genotype, P = 0.01) and between KITLG_rs1508595 and TGCTs (G allele, P = 0.0001; GG genotype, P = 0.0007). Moreover, there was a significant difference in BMP7_rs388286 between the TGCT group and the control (T allele, P = 0.00004; TT genotype, P = 0.00006) and between the TM group and the control (T allele, P = 0.04). HOXD also demonstrated a strong association with TGCTs (rs17198432 A allele, P = 0.0001; AA genotype, P = 0.001). Furthermore, significant differences were found between the TGCT group and the control in the BAK1_rs210138 G allele (P = 0.03) and the GG genotype (P = 0.01). KITLG and BMP7 genes, associated with the development of TGCTs, may also be related to TM. In summary, the KITLG GG_rs995030, GG_rs1508595, BMP7 TT_rs388286, HOXD AA_rs17198432, and BAK1 GG_rs210138 genotypes were associated with a high risk of TGCT development.

Association between risk factors and testicular microlithiasis

Background

Testicular microlithiasis and its clinical significance are not fully understood. Testicular microlithiasis and risk factors have been associated with testicular cancer. The role of testicular microlithiasis is investigated.

Purpose

To investigate the association between testicular microlithiasis and socioeconomic and other pre-diagnostic factors.

Material and Methods

All men who had a scrotal ultrasound examination at the Department of Radiology, Vejle Hospital, during 2001–2013 were included. They were categorized as patients with and without testicular microlithiasis and compared with pre-diagnostic data from a nationwide registry. A total of 2404 men (283 [11.8%] with testicular microlithiasis and 2121 [88.2%] without testicular microlithiasis) were included. The association between testicular microlithiasis and pre-diagnostic conditions was investigated with logistic regression.

Results

Overall, we found no statistically significant differences in demographics, socioeconomic characteristics, or testicular diseases in men with and without testicular microlithiasis. Men with testicular microlithiasis had more often been treated for infertility (odds ratio [OR] 2.09, 95% confidence interval [CI] 0.84–5.24) and testicular torsion (OR 1.58, 95% CI 0.34–7.36) compared to men without testicular microlithiasis. We found no association between sexually transmitted diseases and testicular microlithiasis.

Conclusion

Treatment for infertility and torsion was non-significantly associated with testicular microlithiasis and no other association was found. These data do not suggest early exposure is related to testicular microlithiasis.

Testicular microlithiasis and testicular tumor: a review of the literature

Introduction

There are numerous scientific publications on testicular microlithiasis (TML) detected during ultrasound (US) examination. We wished to update the data.

Methods

PubMed was used to identify original articles published between 1998 and May 2017 describing the association between TML and testicular tumor. Studies were only included if TML was diagnosed by US. Studies were then classified into subgroups according to the following criteria: asymptomatic, symptomatic, infertility, cryptorchidism, family or personal history of testicular cancer, and “no given reason for US”. A Z-Test was used to identify differences within these subgroups. In addition, we identified prospective cohorts of TML patients. Numbers, duration of follow-up, and occurrence of the “testicular tumor” event were recorded for each of them.

Results

One hundred and seventy-five articles were identified, 40 of which were included. Our review has not showed a clear evidence that cryptorchidism associated with TML is a risk factor for testicular tumor. However, there seems to be a correlation between infertility associated with TML and a higher tumor risk. There were not enough studies to confirm a relationship between family or personal history associated with TML and the tumor risk. There was also a correlation with a higher tumor risk for symptomatic associated with TML and “no given reason for US” plus TML groups. However, these groups are assumed to contain bias and caution must be taken regarding conclusions. Regarding the prospective cohort studies, 16 testicular tumors appeared in the follow-up of patients with TML, 13 patients had risk factors.

Conclusion

In cases of TML incidental finding by US with the presence of risk factors (personal history of testicular cancer, testicular atrophy, infertility, cryptorchidism) a consultation with a specialist should be considered. In the absence of risk factors, the occurrence of testicular cancer in patients with TML is similar to the risk of the general population.

Bilateral methachronous testicular germ cell tumor and testicular microlithiasis in a child: Genetic analysis and insights. A case report

OBJECTIVES

To report our experience with a case of a child with bilateral testicular micro-lithiasis (TML) who developed bilateral metachronous testicular germ cell tumor (TGCT) and determine the most appropriate follow-up and care management in children with testicular micro calcifications in regards to the theoretical risk of testicular cancer.

CASE REPORT

A 12 year-old boy was diagnosed with TGCT and TML. Ten years after complete remission, he presented with a recurrence on the contralateral testis. Genetic screening was performed on both resected and the patient's karyotype was analyzed.

RESULTS

Blood karyotype was normal. Aberrations were found in the tumor karyotype. CGH array showed alterations in chromosome arm 12p.

DISCUSSION

TML is frequently associated with testicular malignancy in adults: in 16.9% of cases the normal contralateral testicle develops TML in TGCT. Recent works of literature find no relationship between TML and cancer in general, but in patients with additional risks, the relationship becomes stronger. Some authors suggest that environmental components and genetics are determinant factors. This is highly suspected in our reported case. It would seem that TML is not a precancerous lesion per se, but rather a marker of an at-risk situation. Long term evolution is uncertain and regular self-palpation that starts before puberty is the only way to ensure proper screening and monitoring.

CONCLUSION

TML have been suspected to be a sign of testicular dysgenesis syndrome, which yields a risk of developing TGCT in case of noxious associations. In patients with a history of TGCT contralateral TML is alarming and aggressive surgical management should be discussed. Therapeutic education of these patients on self-palpation is the best way to ensure proper follow-up.

Testicular Microlithiasis: Case Report and Literature Review

Testicular microlithiasis is a condition characterized by the ultrasonographic findings with multiple microliths, with the prevalence of 0.6% to 9%. This is a condition of unknown etiology; however, in many cases it may be associated with cryptorchidism, Klinefelter syndrome, Down syndrome, varicocele, testicular torsion and male pseudohermaphroditism. Many retrospective studies point to the association between testicular microlithiasis and testicular cancer.

We report a case of a 50-year-old patient who presented to the urologist because of dysuric symptoms. Ultrasonographic examination of both testicles revealed microcalcifications in large numbers, i.e. “the phenomenon of the starry sky”. More than 20 microcalcifications were present on the cross section of both testicles. Standard laboratory blood tests were normal. Prostate-specific antigen was 1.22 ng/ml. If risk factors for developing cancer are present, some authors recommend a biopsy of the testicles. However, based on the literature review, currently, there is no a strictly defined protocol.

Prevalence of small testicular hyperechogenic foci in subgroups of 382 non-vasectomized, azoospermic men: a retrospective cohort study

Testicular hyperechogenic foci (THF) are associated with Klinefelter's syndrome, cryptorchidism, infertility, and testicular germ cell neoplasia. The aims of the study were to evaluate THF in relation to etiology of azoospermia and to Sertoli cell dysfunction. The structures inside the scrotum of consecutive non‐vasectomized, azoospermic were examined by ultrasonography, and hormone (FSH, LH, testosterone, and prolactin), and genetic analyses (karyotype, Y microdeletions, and CFTR mutations) were performed. At testicular ultrasonography, patients were graduated into: pronounced THF (>7 THF per transducer field), distributed universally (uTHF) or collected in plaques (pTHF), borderline THF (bTHF; 3–7 THF per transducer field), or no THF (<3 THF per transducer field). Diagnostic testicular biopsy was taken open or with TruCut needle (14G). THF status was sufficiently described in 382 of 449 potential participants, and testicular histology was available in 300 cases. Presence of ultrasonographically detectable THF was compared to presence of testicular microlithiasis (TM) detected histologically. Sertoli cell dysfunction was investigated in a subgroup using a three‐stage immunoperoxidase technique for detection of cytokeratin‐18 (CK‐18). The prevalence of THF was 13.4%. uTHF was found in 11 men (2.9%), the pattern was bilateral in four while other four had bTHF in the other testis. pTHF was detected in eight cases (2.1%), and except for one case with Klinefelter's syndrome, pTHF was in all cases occurring unilaterally. bTHF was detected in 32 cases (8.4%), bilaterally in 17 (53%). Pronounced THF was significantly associated with testicular malignancy. CK‐18 was detected in more azoospermic men with sperm production in ≤50% seminiferous tubules than in azoospermic men with spermatogenesis in ≥90% of seminiferous tubules and normal controls (p < 0.05). Unfortunately, TM detected histologically was not detected in any patient expressing THF, and neither THF nor TM was detected in any of the patients examined for CK‐18. Sertoli cell dysfunction was not associated with testicular microlithiasis or hyperechogenic foci.

The genomic landscape of testicular germ cell tumours: from susceptibility to treatment

The genomic landscape of testicular germ cell tumour (TGCT) can be summarized using four overarching hypotheses. Firstly, TGCT risk is dominated by inherited genetic factors, which determine nearly half of all disease risk and are highly polygenic in nature. Secondly KIT-KITLG signalling is currently the major pathway that is implicated in TGCT formation, both as a predisposition risk factor and a somatic driver event. Results from genome-wide association studies have also consistently suggested that other closely related pathways involved in male germ cell development and sex determination are associated with TGCT risk. Thirdly, the method of disease formation is unique, with tumours universally stemming from a noninvasive precursor lesion, probably of fetal origin, which lies dormant through childhood into adolescence and then eventually begins malignant growth in early adulthood. Formation of a 12p isochromosome, a hallmark of TGCT observed in nearly all tumours, is likely to be a key triggering event for malignant transformation. Finally, TGCT have been shown to have a distinctive somatic mutational profile, with a low rate of point mutations contrasted with frequent large-scale chromosomal gains. These four hypotheses by no means constitute a complete model that explains TGCT tumorigenesis, but advances in genomic technologies have enabled considerable progress in describing and understanding the disease. Further advancing our understanding of the genomic basis of TGCT offers a clear opportunity for clinical benefit in terms of preventing invasive cancer arising in young men, decreasing the burden of chemotherapy-related survivorship issues and reducing mortality in the minority of patients who have treatment-refractory disease.

Inter- and intraobserver agreement in detection of testicular microlithiasis with ultrasonography

BACKGROUND

Ultrasonography of the testis is a well-established diagnostic tool in detection of testicular microlithiasis (TML). Operator-dependent diagnostic variation related to skill, knowledge, and operator consistency are factors that influence detection of TML.

PURPOSE

To determine inter- and intraobserver agreement for detection of TML using ultrasonography for a group of physicians with no or limited experience compared to a group of experience senior radiologists.

MATERIAL AND METHODS

Between May and September 2014 a total of six observers evaluated 34 patients scrotal ultrasonography recorded from September to December 2013. The observers were blinded to patient history and previous ultrasonography. Three of the observers had no or limited experience with detection of TML, and three of the observers had more than 15 years of experience. Each observer reviewed all the scrotal ultrasonography recordings twice with a time interval of 3 months.

RESULTS

The inter-observer agreement showed substantial agreement and up to almost perfect agreement (κ = 0.86). Both the experienced and less experienced observers had a higher agreement in detecting and grading TML in their second reading.

CONCLUSION

The ultrasonography grading system of TML in this study showed to be reproducible, with an inter- and intraobserver agreement ranging between substantial agreement and up to almost perfect agreement with many years of experience not necessarily being essential.

Prospectively Identified Incident Testicular Cancer Risk in a Familial Testicular Cancer Cohort

BACKGROUND

Human testicular germ cell tumors (TGCT) have a strong genetic component and a high familial relative risk. However, linkage analyses have not identified a rare, highly penetrant familial TGCT (FTGCT) susceptibility locus. Currently, multiple low-penetrance genes are hypothesized to underlie the familial multiple-case phenotype. The observation that two is the most common number of affected individuals per family presents an impediment to FTGCT gene discovery. Clinically, the prospective TGCT risk in the multiple-case family context is unknown.

METHODS

We performed a prospective analysis of TGCT incidence in a cohort of multiple-affected-person families and sporadic-bilateral-case families; 1,260 men from 140 families (10,207 person-years of follow-up) met our inclusion criteria. Age-, gender-, and calendar time-specific standardized incidence ratios (SIR) for TGCT relative to the general population were calculated using SEER*Stat.

RESULTS

Eight incident TGCTs occurred during prospective FTGCT cohort follow-up (versus 0.67 expected; SIR = 11.9; 95% CI, 5.1-23.4; excess absolute risk = 7.2/10,000). We demonstrate that the incidence rate of TGCT is greater among bloodline male relatives from multiple-case testicular cancer families than that expected in the general population, a pattern characteristic of adult-onset Mendelian cancer susceptibility disorders. Two of these incident TGCTs occurred in relatives of sporadic-bilateral cases (0.15 expected; SIR = 13.4; 95% CI, 1.6-48.6).

CONCLUSIONS

Our data are the first to indicate that despite relatively low numbers of affected individuals per family, members of both multiple-affected-person FTGCT families and sporadic-bilateral TGCT families comprise high-risk groups for incident testicular cancer.

IMPACT

Men at high TGCT risk might benefit from tailored risk stratification and surveillance strategies.

Familial testicular germ cell tumors (FTGCT) - overview of a multidisciplinary etiologic study

This Review summarizes the cumulative results of the National Cancer Institute Clinical Genetics Branch Multidisciplinary Etiologic Study of Familial Testicular Germ Cell Tumors (FTGCT). Initiated 12 years ago, this protocol enrolled 724 subjects from 147 unrelated families with either ≥2 affected men (n = 90) with TGCT or a proband with bilateral TGCT and a negative family history for this cancer (n = 57). Data were collected directly from 162 subjects evaluated at the NIH Clinical Center, and 562 subjects provided information from their home communities (Field Cohort). The primary study aims included (i) ascertaining, enrolling eligible FTGCT kindred, (ii) characterizing the clinical phenotype of multiple-case families, (iii) identifying the underlying genetic mechanism for TGCT susceptibility in families, (iv) evaluating counseling, psychosocial, and behavioral issues resulting from membership in an FTGCT family, and (v) creating an annotated biospecimen repository to permit subsequent translational research studies. Noteworthy findings include (i) documenting the epidemiologic similarities between familial and sporadic TGCT, (ii) demonstrating significantly younger age-at-diagnosis for familial vs. sporadic TGCT, (iii) absence of a dysmorphic phenotype in affected family members, (iv) shifting the focus of gene discovery from a search for rare, highly penetrant susceptibility variants to the hypothesis that multiple, more common, lower penetrance genes underlie TGCT genetic risk, (v) implicating testicular microlithiasis in FTGCT risk, and (vi) observing that aberrant methylation may contribute to FTGCT risk. A clinically based, biospecimen-intensive, multidisciplinary research strategy has provided novel, valuable insights into the etiology of FTGCT, and created a research resource which will support FTGCT clinical and laboratory studies for years to come.

Testicular microlithiasis: is it significant?

Previously considered to be a benign finding on scrotal ultrasonography, testicular microlithiasis (TM) is now recognized as a condition associated with the development of testicular neoplasia. Despite this the management of TM remains unclear. We review the evidence for this association and suggested management strategies.

Close ties: an exploratory Colored Eco-Genetic Relationship Map (CEGRM) study of social connections of men in Familial Testicular Cancer (FTC) families

BACKGROUND

Testicular cancer, while rare compared with other adult solid tumors, is the most common cancer in young men in northern Europe and North America. Risk factors include white race, positive family history, contralateral testicular cancer, cryptorchidism, infertility and testicular microlithiasis. As the genetic causes of familial clusters (Familial Testicular Cancer or FTC) are being sought, it is also important to understand the psycho-social experiences of members of FTC families.

METHODS

This is a cross-sectional examination via the Colored Eco-Genetic Relationship Map (CEGRM) of social connections reported by 49 men in FTC families participating in NCI research study 02-C-178.

RESULTS

The CEGRM was acceptable and feasible for use with men in FTC families, and valuable in understanding their social connections. These men have largely adjusted to the TC history in themselves and/or their relatives. They have considerable social and emotional support from family and friends, although there is wide variability in sources and types.

CONCLUSIONS

The CEGRM focuses on men's social connections and close emotional bonds in FTC families. This action-oriented process of placing colored symbols on significant relationships uncovered previously under-appreciated emotions accompanying men's social exchanges. Most men in FTC families succeed in re-establishing a sense of normalcy in their lives and social connections, in the aftermath of a testicular cancer diagnosis.

Acquired undescended testis: putting the pieces together

Acquired undescended testis is now a well-recognized disorder. It is seen in 1.5% of pre-pubertal boys and accounts for the 1-2% orchidopexy rate in older boys. Its pathogenesis remains largely unclear, but it may be caused by a fibrous remnant of the processus vaginalis. There is much controversy over its management, and the proper management awaits a randomized-controlled trial. Until now, follow-up data are available only for cases of spontaneous descent or pubertal orchidopexy. It is speculated that acquired undescended testis is in fact congenital and because of a short funiculus at birth, allowing a low-scrotal position early in life. However, as the boy grows, the testis might evolve into an undescended state. When testosterone surges at puberty, spontaneous descent occurs in three of every four cases.

Dissecting the molecular pathways of (testicular) germ cell tumour pathogenesis; from initiation to treatment-resistance

Human type II germ cell tumours (GCTs) originate from an embryonic germ cell, either as a primordial germ cell or gonocyte. This start determines the biological as well as clinical characteristics of this type of cancer, amongst others their totipotency as well as their overall (exceptional) sensitivity to DNA damaging agents. The histology of the precursor lesion, either carcinoma in situ or gonadoblastoma, depends on the level of testicularization (i.e. testis formation) of the gonad. The impact of either intrinsic (genetic) - and environmental factors involved in the pathogenesis is demonstrated by disorders of sex development as well as testicular dysgenesis syndrome as risk factors, including cryptorchidism, hypospadias and disturbed fertility as parameters. This knowledge allows identification of individuals at risk for development of this type of cancer, being a population of interest for screening. Factors known to regulate pluripotency during embryogenesis are proven to be of diagnostic value for type II GCTs, including OCT3/4, even applicable for non-invasive screening. In addition, presence of stem cell factor, also known as KITLG, allows distinction between delayed matured germ cells and the earliest stages of malignant transformation. This is of special interest because of the identified association between development of type II GCTs of the testis and a limited number of single nucleotide polymorphisms, including some likely related to KITL. Transition from the precursor lesion to an invasive cancer is associated with gain of the short arm of chromosome 12, in which multiple genes might be involved, including KRAS2 and possibly NANOG (pseudogenes). While most precursor lesions will progress to an invasive cancer, only a limited number of cancers will develop treatment resistance. Putative explanatory mechanisms are identified, including presence of microsatellite instability, BRAF mutations, apoptosis suppression and p21 sub-cellular localization. It remains to be investigated how these different pathways integrate to each other and how informative they are at the patient-individual level. Further understanding will allow development of more targeted treatment, which will benefit quality of life of these young cancer patients.

Familial testicular germ cell tumors in adults: 2010 summary of genetic risk factors and clinical phenotype

Familial aggregations of testicular germ cell tumor (FTGCT) have been well described, suggesting the existence of a hereditary TGCT subset. Approximately 1.4% of newly diagnosed TGCT patients report a positive family history of TGCT. Sons and siblings of TGCT patients have four- to sixfold and eight- to tenfold increases in TGCT risk respectively. Segregation analyses suggest an autosomal recessive mode of inheritance. Linkage analyses have identified several genomic regions of modest interest, although no high-penetrance cancer susceptibility gene has been mapped yet. These data suggest that the combined effects of multiple common alleles, each conferring modest risk, might underlie familial testicular cancer. Families display a mild phenotype: the most common number of affected families is 2. Age at diagnosis is 2-3 years younger for familial versus sporadic cases. The ratio of familial seminoma to nonseminoma is 1.0. FTGCT is more likely to be bilateral than sporadic TGCT. This syndrome is cancer site specific. Testicular microlithiasis is a newly recognized FTGCT component. Candidate gene-association studies have implicated the Y chromosome gr/gr deletion and PDE11A gene mutations as genetic modifiers of FTGCT risk. Two genomewide association studies of predominantly sporadic but also familial cases of TGCT have implicated the KIT-ligand, SPRY4, and BAK1 genes as TGCT risk modifiers. All five loci are involved in normal testicular development and/or male infertility. These genetic data provide a novel insight into the genetic basis of FTGCT, and an invaluable guide to future TGCT research.

Familial testicular germ cell tumours

This article defines familial testicular germ cell tumours (FTGCTs) as testicular germ cell tumours (TGCTs) diagnosed in at least two blood relatives, a situation which occurs in 1-2% of all cases of TGCT. Brothers and fathers of TGCT patients have an 8-10- and 4-6-fold increased risk of TGCT, respectively, and an even higher elevated risk of TGCT in twin brothers of men with TGCT has been observed, suggesting that genetic elements play an important role in these tumours. Nevertheless, previous linkage studies with multiple FTGCT families did not uncover any high-penetrance genes and it has been concluded that the combined effects of multiple common alleles, each conferring a modest risk, might underlie FTGCT. In agreement with this assumption, recent candidate gene-association analyses have identified the chromosome Y gr/gr deletion and mutations in the PDE11A gene as genetic modifiers of FTGCT risk. Moreover, two genome-wide association studies of predominantly sporadic but also familial cases of TGCT have identified three additional susceptibility loci, KITLG, SPRY4 and BAK1. Notably, all five loci are involved in the biology of primordial germ cells, representing the cell of origin of TGCT, suggesting that the tumours arise as a result of disturbed testicular development.

Clinical update on testicular microlithiasis

PURPOSE OF REVIEW

Testicular microlithiasis becomes a greater interdisciplinary issue among urologists, andrologists, gynecologists dedicated to reproductive medicine, pediatricians, radiologists and pathologists. Proposed management ranges from benign neglect, instructing self-examination over follow-up once, regular biannual follow-up including ultrasonography to bilateral testicular biopsy to rule out possible concomitant unclassified intratubular germ cell neoplasia (ITGCN) or future development of testicular cancer. The aim of this review is to present an overview of the current dilemma and summarize management trends based on the most recent data.

RECENT FINDINGS

Testicular microlithiasis is not a premalignant condition but may accompany ITGCN or testicular cancer. The importance of ruling out ITGCN with testicular biopsy in high-risk men, such as in those with bilateral testicular microlithiasis, infertility, cryptorchidism, atrophic testes or contralateral testicular cancer, has been recently advocated.

SUMMARY

Despite greater awareness of testicular microlithiasis, a clear definition is currently missing and the etiology is still obscure. This causes confusion in management and follow-up. Self-examination alone or in combination with testicular ultrasonography has been advised. Recently, a single set of biopsies in selected, high-risk groups has been proposed to rule out ITGCN without a need for further investigations apart from self-examination. However, the cost-effectiveness of such a strategy needs to be evaluated.

Occurrence of testicular microlithiasis in androgen insensitive hypogonadal mice

BACKGROUND

Testicular microliths are calcifications found within the seminiferous tubules. In humans, testicular microlithiasis (TM) has an unknown etiology but may be significantly associated with testicular germ cell tumors. Factors inducing microlith development may also, therefore, act as susceptibility factors for malignant testicular conditions. Studies to identify the mechanisms of microlith development have been hampered by the lack of suitable animal models for TM.

METHODS

This was an observational study of the testicular phenotype of different mouse models. The mouse models were: cryptorchid mice, mice lacking androgen receptors (ARs) on the Sertoli cells (SCARKO), mice with a ubiquitous loss of androgen ARs (ARKO), hypogonadal (hpg) mice which lack circulating gonadotrophins, and hpg mice crossed with SCARKO (hpg.SCARKO) and ARKO (hpg.ARKO) mice.

RESULTS

Microscopic TM was seen in 94% of hpg.ARKO mice (n=16) and the mean number of microliths per testis was 81+/-54. Occasional small microliths were seen in 36% (n=11) of hpg testes (mean 2+/-0.5 per testis) and 30% (n=10) of hpg.SCARKO testes (mean 8+/-6 per testis). No microliths were seen in cryptorchid, ARKO or SCARKO mice. There was no significant effect of FSH or androgen on TM in hpg.ARKO mice.

CONCLUSION

We have identified a mouse model of TM and show that lack of endocrine stimulation is a cause of TM. Importantly, this model will provide a means with which to identify the mechanisms of TM development and the underlying changes in protein and gene expression.

Testicular microlithiasis and carcinoma in situ overview and proposed clinical guideline

Testicular microlithiasis (TM) has been associated with testicular germ cell tumours (TGCTs) in adolescents and adults and with its precursor carcinoma in situ (CIS). A clear definition of TM and the need for further diagnostics and follow-up is lacking. We reviewed the literature of TM and its association with TGCT/CIS and current follow-up advises and propose a management approach based on associated risk factors for TGCT. In the literature, a wide variance of TM incidence is reported in different patient populations. A consensus concerning the malignant potential of TM has not been reached. In addition, a clear definition on TM is lacking. Although a correlation between TM and TGCT or CIS is found, precise management and follow-up schedules are absent. We suggest that all hyperechogenic foci smaller than 3 mm without shadowing should be named TM irrespective of their number. In addition, we suggest a management scheme for physicians encountering TM in daily practice. Our algorithm suggests taking a testicular biopsy in a selected patient population with at least one additional risk factor for TGCT. A long-term active follow-up schedule, including ultrasonography and physical examinations, is not indicated in the remaining patients with TM.

Increased prevalence of testicular microlithiasis in men with familial testicular cancer and their relatives

Testicular germ cell tumours (TGCT) cluster in families, but responsible genes remain unidentified. The association between testicular microlithiasis (TM) and testicular carcinoma in situ (CIS) suggests that TM may be a TC risk factor. We report testicular ultrasound findings in men with familial TGCT (FTGCT) and their unaffected relatives. A total of 81 men (48 affected and 33 unaffected) from 31 families with > or =2 TC cases underwent testicular ultrasound. Testicular microlithiasis was defined as either 'classic' (> or =5 microliths) or 'limited' (<5 microliths). Statistical analyses used Fisher's exact test and permutation testing. Testicular microlithiasis was more frequent in the contralateral testicles of men with a history of TGCT (affected men) than in unaffected men (48 vs 24%, P=0.04). The association appeared stronger for classic TM (21 vs 9%) than for limited TM (27 vs 15%). Testicular microlithiases were bilateral in six out of seven (87%) unaffected men. Among affected men, TM was not associated with histology, age at diagnosis or cancer treatment. Of the 31 families, 10 accounted for a majority (61%) of the TM cases identified (P=0.11). Testicular microlithiasis was more prevalent among FTGCT family members than described previously in the general population, and was more common among FTGCT cases vs unaffected blood relatives. Testicular microlithiasis appeared to cluster in certain families. These findings suggest both a familial predisposition to TM and an association between TM and FTGCT. If proven, this could be clinically important to men in FTGCT families, and may be useful in identifying specific genes involved in FTGCT.

Testicular microlithiasis in siblings: clinical implications

Testicular microlithiasis is a relatively uncommon condition in children. It is characterized by the presence of microcalcifications within the testicular parenchyma. Although it is a benign finding, underlying diseases and other conditions must be ruled out because testicular microlithiasis has been found in association with both benign and malignant lesions in the testes and other tissues. We present two brothers with testicular microlithiasis, and highlight the prevalence, natural history, associated malignant conditions and follow-up recommendations of children diagnosed with testicular microlithiasis.