WHO 2022 classification of penile and scrotal cancers: updates and evolution.

Squamous cell carcinoma (SCC) is the most common malignant tumour of the penis. The 2022 WHO classification reinforces the 2016 classification and subclassifies precursor lesions and tumours into human papillomavirus (HPV)-associated and HPV-independent types. HPV-associated penile intraepithelial neoplasia (PeIN) is a precursor lesion of invasive HPV- associated SCC, whereas differentiated PeIN is a precursor lesion of HPV-independent SCC. Block-type positivity of p16 immunohistochemistry is the most practical daily utilised method to separate HPVassociated from HPVindependent penile SCC. If this is not feasible, the term SCC, not otherwise specified (NOS) is appropriate. Certain histologies that were previously classified as "subtypes" are now grouped, and coalesced as "patterns", under the rubric of usual type SCC and verrucous carcinoma (e.g. usual-type SCC includes pseudohyperplastic and acantholytic/pseudoglandular carcinoma, and carcinoma cuniculatum is included as a pattern of verrucous carcinoma). If there is an additional component of the usual type of invasive SCC (formerly termed hybrid histology), the tumour would be a mixed carcinoma (e.g. carcinoma cuniculatum or verrucous carcinoma with usual invasive SCC); in such cases, reporting of the relative percentages in mixed tumours may be useful. The consistent use of uniform nomenclature and reporting of percentages will inform the refinement of future reporting classification schemes and guidelines/recommendations. The classification of scrotal tumours is provided for the first time in the fifth edition of the WHO Blue book, and it follows the schema of penile cancer classification for both precursor lesions and the common SCC of the scrotum. Basal cell carcinoma of the scrotum may have a variable clinical course and finds a separate mention.

Dataset for the reporting of carcinoma of the bladder-cystectomy, cystoprostatectomy and diverticulectomy specimens: recommendations from the International Collaboration on Cancer Reporting (ICCR).

The International Collaboration on Cancer Reporting (ICCR) is a not for profit organisation whose goal is to produce standardised internationally agreed and evidence-based datasets for pathology reporting. With input from pathologists worldwide, the datasets are intended to be uniform and structured. They include all items necessary for an objective and accurate pathology report which enables clinicians to apply the best treatment for the patient. This dataset has had input from a multidisciplinary ICCR expert panel. The rationale for some items being required and others recommended is explained, based on the latest literature. The dataset incorporates data from the World Health Organization (WHO) 2016, and also from the latest (8th edition) TNM staging system of the American Joint Committee on Cancer (AJCC). Fifteen required elements and eight recommended items are described. This dataset provides all the details for a precise and valuable pathology report required for patient management and prognostication. This dataset is intended for worldwide use, and should facilitate the collection of standardised comparable data on bladder carcinoma at an international level.

Risk factors for cerebrospinal fluid shunt infections during an outbreak: a case-control study.

BACKGROUND: There are few published reports of cerebrospinal fluid (CSF) shunt infection outbreaks. In 2017-2018, British Columbia Children's Hospital (BCCH) experienced an increase in CSF shunt infections co-incident with a move to new operating rooms and a change in shunt catheters used. AIMS: To describe how an outbreak was detected, investigations were undertaken to determine the cause, risk factors associated with CSF shunt infection during the outbreak, and changes implemented to attempt to control the outbreak. METHODS: Retrospective case-control study. Population included patients who underwent new shunt insertion or revision. Univariate logistic regression models were fitted for each of the variables. Associations with P-values <0.2 were considered of potential interest for further investigation. FINDINGS: There were six cases of CSF shunt infection and 19 controls. The causative organism was different in each case. The only risk factors that met the criteria for further investigation were being a neonate at the time of surgery [odds ratio (OR) 9.0, 95% confidence interval (CI) 0.7-125.3, P=0.10] and the presence of gastrointestinal disease (OR 3.8, 95% CI 0.5-26.2, P=0.18). No association was found with the operating room used or the surgical staff. In response to the outbreak, human traffic through the operating rooms was limited, rigid adherence to the wearing of surgical masks was enforced, and return to the previous CSF shunt catheters used was implemented. CONCLUSION: No modifiable risk factors were associated with CSF shunt infection. After implementation of surgical protocol changes, no further cases of CSF shunt infection linked to the outbreak were identified.

Dataset for the reporting of urinary tract carcinoma-biopsy and transurethral resection specimen: recommendations from the International Collaboration on Cancer Reporting (ICCR).

The International Collaboration on Cancer Reporting (ICCR) is an alliance of major pathology organisations in Australasia, Canada, Europe, United Kingdom, and United States of America that develops internationally standardised, evidence-based datasets for the pathology reporting of cancer specimens. This dataset was developed by a multidisciplinary panel of international experts based on previously published ICCR guidelines for the production of cancer datasets. It is composed of Required (core) and Recommended (noncore) elements identified on the basis of literature review and expert consensus. The document also includes an explanatory commentary explaining the rationale behind the categorization of individual data items and provides guidance on how these should be collected and reported. The dataset includes nine required and six recommended elements for the reporting of cancers of the urinary tract in biopsy and transurethral resection (TUR) specimens. The required elements include specimen site, operative procedure, histological tumor type, subtype/variant of urothelial carcinoma, tumor grade, extent of invasion, status of muscularis propria, noninvasive carcinoma, and lymphovascular invasion (LVI). The recommended elements include clinical information, block identification key, extent of T1 disease, associated epithelial lesions, coexistent pathology, and ancillary studies. The dataset provides a structured template for globally harmonized collection of pathology data required for management of patients diagnosed with cancer of the urinary tract in biopsy and TUR specimens. It is expected that this will facilitate international collaboration, reduce duplication of effort in updating current national/institutional datasets, and be particularly useful for countries that have not developed their own datasets.

Reconsidering the role of pelvic lymph node dissection with radical prostatectomy for prostate cancer in an era of improving radiological staging techniques.

BACKGROUND: Performing an extended pelvic lymph node dissection (PLND) on all men with intermediate- and high-risk prostate cancer at the time of a radical prostatectomy (RP) remains controversial. The majority of patients PLND histology is benign, and the long-term cancer-free progression in men with positive lymph node metastasis is low. The objective is to investigate the probability of long-term biochemical freedom from recurrent disease (bNED) in men with lymph node metastasis identified at the time of radical prostatectomy (RP). SUBJECTS AND METHODS: A retrospective review of the pathology of 1184 pelvic lymph node dissections performed at the time of a radical prostatectomy by multiple surgeons referred to a single uro-pathology laboratory between 2008 and 2014 identified 61 men with node-positive prostate cancer. Of the men with positive nodes, 24 had a standard PLND and 37 an extended PLND (ePLND). bNED was defined as a post-operative serum PSA < 0.2 ng/ml. RESULTS: The median follow-up is 4 years (2-8). The median lymph node count was 7 (range 2-16) for PLND and 22 (range 6-46) for the ePLND. A single lymph node metastasis was identified in 56% of the 61 men. Only 10% of men with a positive lymph node metastasis remained free of biochemical recurrence of disease, and only 5% had undetectable serum PSA. There was no difference in bNED outcome between a PLND and ePLND. The number of men needed to be treated with a PLND at the time of RP (NNT) to result in an undetectable post-operative PSA at a median follow-up of 4 years is 395. CONCLUSIONS: In men with lymph node metastasis, the probability of long-term bNED is low and the NNT for cure is high. With emerging improved radiological imaging techniques increasing the detection of lymph node metastasis outside the extended lymph node dissection templates, more scientific investigation is required to evaluate which men will benefit from a PLND and which men can avoid an unnecessary PLND procedure.

Interventions to improve patient hand hygiene: a systematic review.

Nosocomial pathogens may be acquired by patients via their own unclean hands, but there has been relatively little emphasis on patient hand hygiene as a tool for preventing healthcare-associated infections (HCAIs). The aim of this systematic review was to determine the efficacy of patient hand hygiene interventions in reducing HCAIs and improving patient hand hygiene rates compared to usual care. Electronic databases and grey literature were searched to August 2014. Experimental and quasi-experimental studies were included if they evaluated a patient hand hygiene intervention conducted in an acute or chronic healthcare facility and included HCAI incidence and/or patient hand hygiene rates as an outcome. All steps were performed independently by two investigators. Ten studies were included, most of which were uncontrolled before-after studies (N=8). The majority of interventions (N=7) were multi-modal, with components similar to healthcare worker hand hygiene programmes, including education, reminders, audit and feedback, and provision of hand hygiene products. Six studies reported HCAI outcomes and four studies assessed patient hand hygiene rates; all demonstrated improvements but were at moderate to high risk of bias. In conclusion, interventions to improve patient hand hygiene may reduce the incidence of HCAIs and improve hand hygiene rates, but the quality of evidence is low. Future studies should use stronger designs and be more selective in their choice of outcomes.

[The 2014 consensus conference of the ISUP on Gleason grading of prostatic carcinoma]. / Konsenskonferenz 2014 der ISUP zur Gleason-Graduierung des Prostatakarzinoms.

In 2005 the International Society of Urological Pathology (ISUP) held a concensus conference on Gleason grading in order to bring this grading system up to the current state of contemporary practice; however, it became clear that further modifications on the grading of prostatic carcinoma were necessary. The International Society of Urological Pathology therefore held a further consensus conference in 2014 to clarify these points. This article presents the essential results of the Chicago grading meeting.

Does standardised structured reporting contribute to quality in diagnostic pathology? The importance of evidence-based datasets.

Key quality parameters in diagnostic pathology include timeliness, accuracy, completeness, conformance with current agreed standards, consistency and clarity in communication. In this review, we argue that with worldwide developments in eHealth and big data, generally, there are two further, often overlooked, parameters if our reports are to be fit for purpose. Firstly, population-level studies have clearly demonstrated the value of providing timely structured reporting data in standardised electronic format as part of system-wide quality improvement programmes. Moreover, when combined with multiple health data sources through eHealth and data linkage, structured pathology reports become central to population-level quality monitoring, benchmarking, interventions and benefit analyses in public health management. Secondly, population-level studies, particularly for benchmarking, require a single agreed international and evidence-based standard to ensure interoperability and comparability. This has been taken for granted in tumour classification and staging for many years, yet international standardisation of cancer datasets is only now underway through the International Collaboration on Cancer Reporting (ICCR). In this review, we present evidence supporting the role of structured pathology reporting in quality improvement for both clinical care and population-level health management. Although this review of available evidence largely relates to structured reporting of cancer, it is clear that the same principles can be applied throughout anatomical pathology generally, as they are elsewhere in the health system.

Validation of International Society of Urological Pathology (ISUP) grading for prostatic adenocarcinoma in thin core biopsies using TROG 03.04 'RADAR' trial clinical data.

In 2014 a consensus conference convened by the International Society of Urological Pathology (ISUP) adopted amendments to the criteria for Gleason grading and scoring (GS) for prostatic adenocarcinoma. The meeting defined a modified grading system based on 5 grading categories (grade 1, GS 3+3; grade 2, GS 3+4; grade 3, GS 4+3; grade 4, GS 8; grade 5, GS 9-10). In this study we have evaluated the prognostic significance of ISUP grading in 496 patients enrolled in the TROG 03.04 RADAR Trial. There were 19 grade 1, 118 grade 2, 193 grade 3, 88 grade 4 and 79 grade 5 tumours in the series, with follow-up for a minimum of 6.5 years. On follow-up 76 patients experienced distant progression of disease, 171 prostate specific antigen (PSA) progression and 39 prostate cancer deaths. In contrast to the 2005 modified Gleason system (MGS), the hazards of the distant and PSA progression endpoints, relative to grade 2, were significantly greater for grades 3, 4 and 5 of the 2014 ISUP grading scheme. Comparison of predictive ability utilising Harrell's concordance index, showed 2014 ISUP grading to significantly out-perform 2005 MGS grading for each of the three clinical endpoints.

Applying psychological frameworks of behaviour change to improve healthcare worker hand hygiene: a systematic review.

BACKGROUND: Despite the importance of hand hygiene in preventing transmission of healthcare-associated infections, compliance rates are suboptimal. Hand hygiene is a complex behaviour and psychological frameworks are promising tools to influence healthcare worker (HCW) behaviour. AIM: (i) To review the effectiveness of interventions based on psychological theories of behaviour change to improve HCW hand hygiene compliance; (ii) to determine which frameworks have been used to predict HCW hand hygiene compliance. METHODS: Multiple databases and reference lists of included studies were searched for studies that applied psychological theories to improve and/or predict HCW hand hygiene. All steps in selection, data extraction, and quality assessment were performed independently by two reviewers. FINDINGS: The search yielded 918 citations; seven met eligibility criteria. Four studies evaluated hand hygiene interventions based on psychological frameworks. Interventions were informed by goal setting, control theory, operant learning, positive reinforcement, change theory, the theory of planned behaviour, and the transtheoretical model. Three predictive studies employed the theory of planned behaviour, the transtheoretical model, and the theoretical domains framework. Interventions to improve hand hygiene adherence demonstrated efficacy but studies were at moderate to high risk of bias. For many studies, it was unclear how theories of behaviour change were used to inform the interventions. Predictive studies had mixed results. CONCLUSION: Behaviour change theory is a promising tool for improving hand hygiene; however, these theories have not been extensively examined. Our review reveals a significant gap in the literature and indicates possible avenues for novel research.

[Vancouver classification of renal tumors: Recommendations of the 2012 consensus conference of the International Society of Urological Pathology (ISUP)]. / Vancouver-Klassifikation von Nierentumoren : Empfehlungen der Konsenskonferenz der Internationalen Gesellschaft für Uropathologie (ISUP) 2012.

The 2012 consensus conference of the International Society of Urological Pathology (ISUP) has formulated recommendations on classification, prognostic factors and staging as well as immunohistochemistry and molecular pathology of renal tumors. Agreement was reached on the recognition of five new tumor entities: tubulocystic renal cell carcinoma (RCC), acquired cystic kidney disease-associated RCC, clear cell (tubulo) papillary RCC, microphthalmia transcription factor family RCC, in particular t(6;11) RCC and hereditary leiomyomatosis-associated RCC. In addition three rare forms of carcinoma were considered as emerging or provisional entities: thyroid-like follicular RCC, succinate dehydrogenase B deficiency-associated RCC and anaplastic lymphoma kinase (ALK) translocation RCC. In the new ISUP Vancouver classification, modifications to the existing 2004 World Health Organization (WHO) specifications are also suggested. Tumor morphology, a differentiation between sarcomatoid and rhabdoid and tumor necrosis were emphasized as being significant prognostic parameters for RCC. The consensus ISUP grading system assigns clear cell and papillary RCCs to grades 1-3 due to nucleolar prominence and grade 4 is reserved for cases with extreme nuclear pleomorphism, sarcomatoid and/or rhabdoid differentiation. Furthermore, consensus guidelines were established for the preparation of samples. For example, agreement was also reached that renal sinus invasion is diagnosed when the tumor is in direct contact with the fatty tissue or loose connective tissue of the sinus (intrarenal peripelvic fat) or when endothelialized cavities within the renal sinus are invaded by the tumor, independent of the size. The importance of biomarkers for the diagnostics or prognosis of renal tumors was also emphasized and marker profiles were formulated for use in specific differential diagnostics.

Hand hygiene monitoring technology: a systematic review of efficacy.

Electronic and video monitoring systems (EMS/VMS) may improve hand hygiene by providing feedback, real-time reminders or via the Hawthorne effect. The aim of this systematic review was to assess the efficacy of EMS/VMS in improving hand hygiene or reducing the incidence of healthcare-associated infection (HCAI). Experimental and quasi-experimental studies were included if they measured any hand hygiene outcome and/or HCAI incidence. Of the studies included, seven used system-defined compliance (SDC) (N = 6) or hand hygiene event rate (N = 1) as their outcome. SDC differed for all systems. Most (N = 6) were single ward studies. Two uncontrolled pretest‒post-test studies evaluating EMS that provided voice prompts showed increases in SDC, but risk of bias was high. Two uncontrolled time-series analyses of VMS that provided aggregate feedback demonstrated large, sustained improvement in SDC and were at moderate risk of bias. One non-randomized controlled trial of EMS with aggregate feedback found no difference in hand hygiene frequency but was at high risk of bias. Two studies evaluated EMS providing individual feedback and real-time reminders. A pretest‒post-test study at high risk of bias showed an increase in SDC. An RCT at low risk of bias showed 6.8% higher SDC in the intervention arm partially due to a fall in SDC in the control arm. In conclusion, the overall study quality was poor. The study at lowest risk of bias showed only a small increase in SDC. VMS studies at moderate risk of bias showed rapid and sustained increases in SDC. Data were insufficient to recommend EMS/VMS. Future studies should prioritize testing of VMS using stronger study designs including control arms and validated, system-independent measures of hand hygiene.

[Diagnostics of radical prostatectomy specimens. Results of the 2009 consensus conference of the International Society of Urological Pathology]. / Diagnostik radikaler Prostatektomiepräparate. Ergebnisse der Konsensuskonferenz der Internationalen Gesellschaft für Urologische Pathologie 2009.

The 2009 consensus conference of the International Society of Urological Pathology (ISUP) made recommendations for standardization of handling and staging of radical prostatectomy specimens. The conference topics were preparation of specimens, the T2 subclassification, prostate cancer volume, extraprostatic tumor extent, lymphovascular invasion, seminal vesicle infiltration, lymph node metastases and surgical margins. This review article presents the essential results and recommendations of this conference.

Cancer diagnostic assessment programs: standards for the organization of care in Ontario.

BACKGROUND: Improving access to better, more efficient, and rapid cancer diagnosis is a necessary component of a high-quality cancer system. How diagnostic services ought to be organized, structured, and evaluated is less understood and studied. Our objective was to address this gap. METHODS: As a quality initiative of Cancer Care Ontario's Program in Evidence-Based Care, the Diagnostic Assessment Standards Panel, with representation from clinical oncology experts, institutional and clinical administrative leaders, health service researchers, and methodologists, conducted a systematic review and a targeted environmental scan of the unpublished literature. Standards were developed based on expert consensus opinion informed by the identified evidence. Through external review, clinicians and administrators across Ontario were given the opportunity to provide feedback. RESULTS: The body of evidence consists of thirty-five published studies and fifteen unpublished guidance documents. The evidence and consensus opinion consistently favoured an organized, centralized system with multidisciplinary team membership as the optimal approach for the delivery of diagnostic cancer assessment services. Independent external stakeholders agreed (with higher mean values, maximum 5, indicating stronger agreement) that DAP standards are needed (mean: 4.6), that standards should be formally approved (mean: 4.3), and importantly, that standards reflect an effective approach that will lead to quality improvements in the cancer system (mean: 4.5) and in patient care (mean: 4.3). INTERPRETATION: Based on the best available evidence, standards for the organization of DAPS are offered. There is clear need to integrate formal and comprehensive evaluation strategies with the implementation of the standards to advance this field.

[Mucinous spindle cell carcinoma of the kidney. A molecular analysis]. / Muzinöses, tubuläres und spindelzelliges Nierenkarzinom. Eine molekulare Analyse.

The new WHO-classification of renal tumors includes new subtypes, one of which is the mucinous, tubular, and spindle cell carcinoma. Many of these tumors had been previously diagnosed as sarcomatoid carcinoma. There are areas of cord-like growth and spindle cell configuration, sometimes with a clear cell appearance. The cells have low-grade nuclear features. It has been postulated that these tumors are related to the loop of Henle. In this study, 21 tumors were immunohistochemically and genetically analyzed. The analysis showed complex genomic aberrations, but no chromosome 3p losses. Fluorescence in situ hybridization detected no von Hippel-Lindau gene deletions on chromosome 3p25, which are characteristic for clear cell renal carcinomas. These findings show that there is no genetic relationship to clear cell renal carcinomas. The results of the immunohistochemical analyses showed a complex immunophenotype, but could not prove a derivation from the loop of Henle. The prognosis of these tumors seems to be favorable.

Leiomyosarcoma of urinary bladder following cyclophosphamide therapy: report of two cases.

Leiomyosarcoma of urinary bladder is rare, although it is the most common mesenchymal tumor in adults. We report two cases of this tumor following cyclophosphamide therapy. The first case is from a 53-year-old man with Wegener's granulomatosis treated for 6 years with cyclophosphamide. He presented with painless hematuria, and the initial biopsy of the bladder tumor revealed a malignant spindle cell neoplasm. A final diagnosis of leiomyosarcoma was made on radical cystoprostatectomy. The second example is from a 21-year-old man who had received cyclophosphamide in early infancy for a bilateral retinoblastoma. He also presented with painless hematuria, and a bladder tumor was resected transurethrally and diagnosed as leiomyosarcoma. He underwent partial cystectomy two months later. Cyclophosphamide, when used for a neoplastic or non-neoplastic condition, is associated with an increased risk of developing bladder cancer. The distribution of histologic subtypes differs from that seen in spontaneous bladder tumors. A review of the literature shows an increased proportion of squamous cell carcinomas and sarcomas, especially leiomyosarcomas in cyclophosphamide exposed patients. Acrolein, a cytotoxic metabolite of cyclophosphamide excreted in urine, is regarded as the most likely causative agent.

Primary extrapulmonary sugar tumor (PEST): a report of four cases.

The cell of origin and direction of differentiation of the clear cell tumor of the lung (the so-called sugar tumor) remains enigmatic. Recognition of HMB-45 immunoreactivity and identification of melanosomes have suggested a relationship to angiomyolipoma of kidney or liver and lymphangiomyoma. This has given rise to the concept that clear cell tumors are neoplasms of so-called perivascular epithelioid cells--PEComas. Herein we report the existence of four similar tumors occurring in extrapulmonary sites, one of which had malignant features. The three benign tumors occurred in females ages 9, 20, and 40 years; two were located in the rectum and one in the vulva. The malignant tumor occurred in the inter-atrial cardiac septum of a 29-year-old man. Common histologic features were a richly vascular organoid architecture, tumor cells with clear to pale eosinophilic cytoplasm, abundant glycogen, and immunoreactivity for HMB 45, but not S100, multiple keratin, neuroendocrine, or muscle markers. Benign tumors demonstrated low mitotic activity, no necrosis, and good circumscription; the malignant tumor showed considerable mitotic activity, necrosis, and an infiltrative growth pattern. Ultrastructurally, glycogen was present, mitochondria were abundant, and membrane-bound lamellated bodies consistent with premelanosomes were present in two cases, and equivocal in one. Because these tumors have light microscopic, immunohistochemical, and electron microscopic features similar to pulmonary sugar tumors, we propose the name primary extrapulmonary sugar tumor (PEST) for them. Although most PEST's are probably benign, malignant forms appear to exist. These cases further support the concept of a family of systemic HMB-45 positive tumors that include sugar tumors, angiomyolipoma of kidney or liver, lymphangiomyomas, and clear-cell myomelanocytic tumors of the falciform ligament/ligamentum teres.

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.

It is controversial if the rare dermoid cyst of the testis should be classified as a variant of mature teratoma or separately. The spectrum of findings is also ill defined, as is the relationship of dermoid cyst to intratubular germ cell neoplasia of the unclassified type (IGCNU). This study therefore reports the findings in five testicular dermoid cysts that occurred in five patients, 17-42 years of age, who presented with testicular masses. Four lesions consisted of a keratin-filled cyst with a thickened wall, whereas one had islands of "shadow" squamous epithelial cells with superimposed calcification and ossification (pilomatrixoma-like variant). Hair was identified grossly in two cases. On microscopic examination, four tumors had hair follicles with sebaceous glands showing a typical, cutaneous-type orientation to an epidermal surface, although no hair shafts were present in two. In addition, the fibrous wall contained smooth muscle bundles (all tumors) and eccrine or apocrine sweat glands (4 tumors). In some cases there were also glands lined by ciliated epithelium (4 tumors, including the pilomatrixoma-like variant), intestinal mucosa (1 tumor), and bone (2 tumors). There was no cytologic atypia or apparent mitotic activity, and no case had IGCNU in the seminiferous tubules. All patients were clinical stage I and were treated by orchiectomy without adjuvant therapy. All were well on follow-up from 1.5 to 9.5 years later. This study supports that dermoid cyst may have noncutaneous teratomatous elements and that an important criterion for its diagnosis is the absence of IGCNU. It also supports that it should be categorized separately from mature testicular teratoma because of the malignant nature of the latter in postpubertal patients. These observations suggest that there are at least two pathways for testicular teratomas in postpubertal patients: the more common being through IGCNU by differentiation from an invasive malignant germ cell tumor and the less common one, taken by dermoid cyst, by direct transformation from a nonmalignant germ cell.

Mixed epithelial and stromal tumor of the kidney lacks the genetic alterations of cellular congenital mesoblastic nephroma.

Mixed epithelial and stromal tumor of the kidney is a recently recognized neoplasm that occurs almost exclusively in perimenopausal women. Because it frequently contains areas of smooth muscle in which epithelial structures are embedded, some have concluded that it is the adult form of congenital mesoblastic nephroma. Others have concluded that the morphology and epidemiology of mixed epithelial and stromal tumor indicate that it is unrelated to congenital mesoblastic nephroma. Although the genetic alterations of mixed epithelial and stromal tumor have not been previously elucidated, much is known about the genetic alterations of cellular congenital mesoblastic nephroma. The present study was undertaken to determine if mixed epithelial and stromal tumors have any of the genetic alterations recognized as typical of cellular congenital mesoblastic nephroma. RNA extraction was performed on formalin-fixed, paraffin-embedded tissue from 7 mixed epithelial and stromal tumors followed by reverse-transcription polymerase chain reaction to detect the ETV6-NTRK3 gene fusion. Fluorescent in situ hybridization with centromere-specific probes for chromosomes 8, 11, and 17 was performed to evaluate polyploidy of these chromosomes in 11 cases of mixed epithelial and stromal tumor. None of the mixed epithelial and stromal tumors showed any of these genetic alterations. We conclude that mixed epithelial and stromal tumor of the kidney lacks the genetic alterations typical of cellular congenital mesoblastic nephroma, is unrelated to it, and the appellation "adult mesoblastic nephroma" should not be used for these tumors.