Clear cell adenocarcinoma and nephrogenic adenoma of the urethra and urinary bladder: a histopathologic and immunohistochemical comparison

Clinicopathological study of 34 cases of clear cell adenocarcinoma of the urinary tract and diagnostic value of SOX 17 in its differential diagnosis

Clear cell adenocarcinoma (CCA) of the urinary tract is a rare tumor with a female predominance. The morphological features and immunoprofile of urinary CCA, CCA of the gynecologic tract (Gyn CCA), and nephrogenic adenoma (NA) can show extensive overlap, and the differential diagnosis can be challenging especially in small biopsies. SOX17 is a newly identified sensitive and specific immunomarker for endometrial and ovarian carcinomas including Gyn CCA. However, its expression in urinary CCA and NA has not been studied. We studied clinical and pathological features of 34 cases of urinary CCA, the largest cohort in the literature to date. We analyzed the expression pattern of SOX17 in a cohort of 34 urinary CCA, 24 Gyn CCA, and 18 NA. Interestingly, 29 % (10/34) of urinary CCA showed high SOX17 expression, while all the NA cases (18/18) showed negative-low expression. In female, 51 % of urinary CCA cases (15/29) show negative-low expression of SOX17, whereas all Gyn CCA (24/24) showed high SOX17 positivity. Our study showed a unique expression pattern of SOX17 in urinary CCA and NA. These results suggest that SOX17 is a useful marker in distinguishing CCA from NA or urinary CCA from Gyn CCA. Moreover, our study suggests different pathogenic pathways for the histogenesis of urinary CCA.

Primary adenocarcinoma of the urinary tract and its precursors: Diagnostic criteria and classification

Primary adenocarcinoma of the urinary bladder is a rare malignancy, comprising up to 2% of bladder cancers, predominantly in males. Its rarity and similarity to urothelial carcinoma and secondary adenocarcinomas pose diagnostic challenges. A comprehensive literature review was conducted on the diagnosis, classification, morphological and immunophenotypic characteristics, and molecular profiles of primary adenocarcinoma, urachal adenocarcinoma, and precursor lesions. Primary adenocarcinoma exhibits diverse morphological patterns, including enteric, mucinous, signet ring cell, and mixed types. Immunohistochemistry is useful in differentiating primary adenocarcinoma from metastatic adenocarcinomas and secondary involvement. Genetic studies reveal mutations common in colorectal and bladder adenocarcinomas (KRAS, TP53, PIK3CA) and novel primary adenocarcinoma-specific mutations (OR2L5). Urachal adenocarcinoma shares morphological features with primary adenocarcinoma but typically occurs in younger patients with unique genomic and distinct immunoprofile. Potential precursor lesions include villous adenoma, cystitis glandularis, and intestinal metaplasia, and warrant close clinical follow-up. Despite advances in histopathological and molecular diagnostics, primary adenocarcinoma remains challenging to diagnose due to its rarity and morphological heterogeneity. Ongoing research into its molecular characteristics is essential to refine diagnostic criteria and therapeutic approaches. Thorough clinical and pathological assessment is crucial for accurate diagnosis, classification, and clinical management.

Distribution of prostatic markers in glands of the female urethra and anterior vaginal wall-a rapid autopsy study

BACKGROUND

There are varying reports of immunohistochemically detected prostatic marker protein distribution in glands associated with the female urethra that may be related to tissue integrity at the time of fixation.

AIM

In this study we used tissue derived from rapid autopsies of female patients to determine the distribution of glandular structures expressing prostate-specific antigen (PSA) and prostate-specific acid phosphatase (PSAP) along the female urethra and in surrounding tissues, including the anterior vaginal wall (AVW).

METHODS

Tissue blocks from 7 donors that contained the entire urethra and adjacent AVW were analyzed. These tissue samples were fixed within 4-12 hours of death and divided into 5-mm transverse slices that were paraffin embedded. Sections cut from each slice were immunolabeled for PSA or PSAP and a neighboring section was stained with hematoxylin and eosin. The sections were reviewed by light microscopy and analyzed using QuPath software.

OBSERVATIONS

In tissue from all donors, glandular structures expressing PSA and/or PSAP were located within the wall of the urethra and were present along its whole length.

RESULTS

In the proximal half of the urethra from all donors, small glands expressing PSAP, but not PSA, were observed adjacent to the and emptying into the lumen. In the distal half of the urethra from 5 of the 7 donors, tubuloacinar structures lined by a glandular epithelium expressed both PSA and PSAP. In addition, columnar cells at the surface of structures with a multilayered transitional epithelium in the distal half of the urethra from all donors expressed PSAP. No glands expressing PSA or PSAP were found in tissues surrounding the urethra, including the AVW.

CLINICAL IMPLICATIONS

Greater understanding of the distribution of urethral glands expressing prostatic proteins in female patients is important because these glands are reported to contribute to the female sexual response and to urethral pathology, including urethral cysts, diverticula, and adenocarcinoma.

STRENGTHS AND LIMITATIONS

Strengths of the present study include the use of rapid autopsy to minimize protein degradation and autolysis, and the preparation of large tissue sections to demonstrate precise anatomical relations within all the tissues surrounding the urethral lumen. Limitations include the sample size and that all donors had advanced malignancy and had undergone previous therapy which may have had unknown tissue effects.

CONCLUSION

Proximal and distal glands expressing prostate-specific proteins were observed in tissue from all donors, and these glands were located only within the wall of the urethra.

Diagnostic Approach to and Differential Diagnosis of Clear Cell and Glandular Lesions of the Lower Urinary Tract

CONTEXT.—

A variety of glandular and clear cell lesions may be seen in the urinary bladder and/or urethra, ranging from benign to malignant primary and secondary tumors. Lesions with no malignant potential include reactive processes, such as nephrogenic metaplasia, and may show similar morphologic features as an infiltrative neoplasm, particularly in small biopsies. Similarly, ectopic tissues of Müllerian origin may be seen in the lower urinary tract, and their distinction from a true glandular neoplasm is essential to avoid overtreatment. A wide variety of primary and secondary malignant tumors exist with varying degrees of glandular and clear cell features. Therefore, surgical pathologists must be aware of the full scope of possible lesions to avoid misdiagnosis.

OBJECTIVE.—

To provide a practical framework for approaching the diagnosis of clear cell and glandular lesions of the urinary bladder/urethra and prostate, highlighting the strengths and limitations of various diagnostic features and ancillary tests.

DATA SOURCES.—

A review of the current literature was performed to obtain data regarding up-to-date diagnostic features and ancillary studies.

CONCLUSIONS.—

In summary, distinct morphologic and immunohistochemical features and clinical and radiologic correlation are essential to establish an accurate diagnosis when such cases with glandular and clear features are encountered in the lower urinary tract.

Management of Primary Female Urethral Adenocarcinoma: Two Rare Case Reports and Literature Review

Primary urethral adenocarcinoma in females is an extremely rare malignancy with unclear origin and only a few retrospective cases have been reported. The controversy continues to exist over the origin of primary urethral adenocarcinoma from periurethral glands (which include the Skene's glands), urethritis glandularis or intestinal metaplasia. Herein, we report one case of a 49-year-old female with distal urethral adenocarcinoma who presented with obstructive voiding. Abdominal and pelvic CT scans and chest radiology were unremarkable. Biopsy of the mass confirmed urethral adenocarcinoma. The patient underwent partial ureterectomy and was disease-free at the 2-years follow-up period. We also present another extremely rare case of primary urethral adenocarcinoma with mucinous features in a 58-year-old female who initially complained of external urethral orifice itching with painless urethral bleeding and was treated with local excision. The patient has not received any neoadjuvant or adjuvant therapy, and experienced tumor recurrence, inguinal lymph nodes metastasis, and even local iliopsoas metastasis during over 10-years follow-up. In conclusion, our current study emphasizes the importance of imaging studies and biopsy in making an accurate preoperative diagnosis of this rare disease, and further highlights the role of multimodal therapy. A combination of radiotherapy, chemotherapy and surgery is recommended for the optimal local and distant disease control. Moreover, better medical compliance and regular follow-up are required in these patients.

Tumour-like lesions of the urinary bladder

There are a number of benign epithelial proliferations in the bladder that may be difficult to distinguish from carcinomas, including urothelial carcinoma and its variants, squamous cell carcinoma and adenocarcinoma. If misdiagnosed, there is the potential for over treatment, with its attendant risk of complications, as well as errors relating to prognostic assessment. In the case of the misdiagnosis of high grade proliferative lesions that mimic invasive carcinoma, unnecessary radical surgery, chemotherapy and radiotherapy may result. Similarly, the misdiagnosis of lesions that have the appearance of low grade carcinoma can prompt a lifetime of radiological investigation and cystoscopies. In this review, we discuss a variety of entities that may be diagnostically challenging and emphasise the importance of identifying key morphological features that have diagnostic utility. We also highlight the importance of relevant clinical information and the clinical settings in which these lesions may occur. In this review we have divided the lesions on the basis of morphology in order to facilitate discussion relating to the differential diagnosis. The architectural patterns we discuss include papillary lesions (polypoid/papillary cystitis and papillary urothelial hyperplasia), pseudocarcinomatous proliferations (pseudocarcinomatous urothelial hyperplasia, florid proliferation of von Brunn nests and fibroepithelial polyps), glandular lesions (intestinal metaplasia and müllerianosis) and lesions with several different patterns (prostatic type urethral polyps and nephrogenic adenoma or metaplasia).

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.

The applicability and utility of immunohistochemical biomarkers in bladder pathology

Urinary bladder specimens are frequently encountered in the daily practice of surgical pathologists. The spectrum of pathologic entities encountered in bladder specimens is extraordinarily broad, and in some instances, immunohistochemical stains are used to help characterize challenging bladder lesions. Cost-effective biomarker selection tailored to the differential diagnosis facilitates an accurate diagnosis. This comprehensive review is prepared as a reference guide for the use of immunohistochemistry to categorize primary and secondary bladder neoplasms and to evaluate metastatic cancers for possible bladder origin.

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.

Molecular profiling of clear cell adenocarcinoma of the urinary tract

Clear cell adenocarcinoma (CCA) of the urinary tract is a rare type of malignancy whose molecular profiles remain undefined. Here we reported an integrated clinicopathologic and molecular profiling analysis of four cases of clear cell adenocarcinoma arising in the urethra or the bladder. Utilizing a clinically validated 130-gene exon-sequencing assay, we identified recurrent pathogenic PIK3CA (p. E545K) and KRAS (p.G12D) variants in three of four (75%) of the cases. In addition, an APC variant (P.S2310X), a TP53 variant (p.R273C), and a MYC amplification event were identified. The only CCA case without either PIK3CA or KRAS variants has a distinct pathogenesis through BK virus, demonstrated by positive BK virus PCR and SV40 immunohistochemistry. The novel finding of recurrent variants in the PI3K/AKT/mTOR pathway provides not only insights into oncogenesis but also potential clinical therapeutic targets for patients with clear cell adenocarcinoma of the urinary tract.

Glandular Tumors of the Urachus and Urinary Bladder: A Practical Overview of a Broad Differential Diagnosis

Primary glandular tumors of the urachus and urinary bladder are an intriguing group of clinically and morphologically diverse neoplasms for which there have been recent refinements in diagnostic subclassification and advances in molecular pathology. In addition, the urachus and urinary bladder may be secondarily involved by tumors with glandular differentiation that demonstrate remarkable morphologic, immunophenotypic, and molecular overlap. Thus, surgical pathologists need to be aware of the broad differential diagnosis of glandular tumors that involve the urachus and urinary bladder and have a practical diagnostic framework to evaluate these lesions in routine clinical practice. In this review, we summarize the salient clinical, morphologic, immunohistochemical, and molecular features of glandular tumors of the urachus and urinary bladder, including mucinous cystic tumors of the urachus, noncystic urachal adenocarcinomas, urothelial carcinomas with glandular or pseudoglandular features, primary urinary bladder adenocarcinomas, and Müllerian-type carcinomas, highlighting the strengths and limitations of various diagnostic features and ancillary tests, as well as the need for close clinical and radiographic correlation.

Non-urothelial carcinomas of the bladder

Non-urothelial carcinomas involving the bladder are uncommon and often diagnostically challenging. These carcinomas may show squamous, adenocarcinomatous or neuroendocrine features, with immunohistochemical stains aiding the diagnosis in only a subset of cases. The clinical history in non-urothelial bladder carcinomas is important, given that the differential diagnosis often includes secondary involvement of the bladder by direct extension or metastasis from carcinomas at other sites. This paper will review non-urothelial carcinomas in each of these three morphological categories, emphasising recent changes in diagnostic grouping and challenges in the histopathological diagnosis. Review of bladder cancers with squamous morphology will include discussion of conventional squamous cell carcinoma and verrucous carcinoma and their distinction from urothelial carcinoma with extensive squamous differentiation. Bladder carcinomas with adenocarcinomatous change will include primary bladder adenocarcinoma, urachal adenocarcinoma and tumours of Müllerian type. Finally, neuroendocrine neoplasms of the bladder, including well-differentiated neuroendocrine tumour and neuroendocrine carcinomas, will be discussed. Associated surface findings, risk factors and prognostic features will be described.

Concordant clear cell "mesonephric" carcinoma of the bladder and lung adenocarcinoma with clear cell features - multiple primaries versus metastatic neoplasms: a case report

BACKGROUND

Clear cell carcinoma of the bladder is a rare variant of urinary bladder adenocarcinoma. We report a case of a patient with clear cell carcinoma of the bladder and a concordant right upper lobe pulmonary adenocarcinoma with clear cell features, and we address the role of immunohistochemistry and cytogenetic analysis in distinguishing the two primary malignancies.

CASE PRESENTATION

Our patient was a 59-year-old African American woman who presented with hematuria. Her past medical history included invasive mammary carcinoma and end-stage renal disease treated with hemodialysis. A computed tomographic urogram revealed a 3-cm polypoid bladder mass. A follow-up chest computed tomographic scan revealed a 1-cm right upper lobe nodule. The patient underwent transurethral biopsy and subsequent radical cystectomy, as well as a transthoracic core needle biopsy of the lung nodule. Histologically, the bladder tumor consisted of flat, cuboidal to columnar cells with clear or eosinophilic cytoplasm and a hobnail appearance, organized in tubulocystic and papillary patterns. The neoplastic cells were diffusely positive for α-methylacyl-coenzyme A racemase, cancer antigen 125, and cytokeratin 7; focally positive for cytokeratin 20, P53, and carcinoembryonic antigen; and negative for thyroid transcription factor 1. The lung tumor demonstrated a glandular architecture with mucin production (positive for mucin with mucicarmine and periodic acid-Schiff with diastase stain). The neoplastic cells were diffusely positive for cytokeratin 7, napsin A, and thyroid transcription factor 1, and they were negative for cytokeratin 20 and cancer antigen 125. Genetic testing of the pulmonary neoplasm demonstrated ARID2 genomic alterations.

CONCLUSIONS

The presence of clear cell features in both neoplasms raised the possibility of lung metastasis from the primary bladder tumor. However, the glandular architecture of the lung neoplasm along with its distinctive immunohistochemical and genetic profiles confirmed the presence of two separate primaries.

Renal-type clear cell carcinoma of the prostate: A case report

Renal-type clear cell carcinoma of the prostate is a rare and novel tumor that has only been identified in recent years. The present study describes a lesion in the prostate of a 64-year-old male with a two-year history of urinary frequency, urgency and difficulty, who was admitted to the San Ai Tang Hospital for benign prostatic hyperplasia, and subsequently underwent transurethral resection of the prostate. In total, 12 g of tissue was resected, which demonstrated morphological and immunohistochemical similarities to clear cell carcinoma of the kidney. Ultrasound inspection and computed tomography revealed prostate enlargement. Although no renal-enclosed mass was identified, metastatic lesions were revealed in the lungs, sternum and clavicles. In addition, right pleural thickening and a small amount of effusion in the pleural cavity were detected. Clear cell carcinoma was identified throughout the prostate, with surrounding regions of ordinary-type prostatic adenocarcinoma (Gleason score, 4+4). The urinary bladder exhibited no dysplasia or neoplasia. It was therefore concluded that the tumor represented a primary renal-type clear cell carcinoma that had arisen in the prostate. To the best of our knowledge, this type of extra-renal tumor has only been reported in three other previous studies.

Nephrogenic Adenoma of the Urinary Bladder: A Review of the Literature

Background. Nephrogenic adenoma of the urinary bladder (NAUB) is a rare lesion associated with nonspecific symptoms and could inadvertently be misdiagnosed. Aim. To review the literature. Methods. Various internet search engines were used. Results. NAUB is a benign tubular and papillary lesion of the bladder, is more common in men and adults, and has been associated with chronic inflammation/irritation, previous bladder surgery, diverticula, renal transplantation, and intravesical BCG; recurrences and malignant transformations have been reported. Differential diagnoses include clear cell adenocarcinoma, endocervicosis, papillary urothelial carcinoma, prostatic adenocarcinoma of bladder, and nested variant of urothelial carcinoma; most NAUBs have both surface papillary and submucosal tubular components; both the papillae and tubules tend to be lined by a single layer of mitotically inactive bland cells which have pale to clear cytoplasm. Diagnosis may be established by using immunohistochemistry (positive staining with racemase; PAX2; keratins stain positive with fibromyxoid variant), electron microscopy, DNA analysis, and cytological studies. Treatment. Endoscopic resection is the treatment but recurrences including sporadic malignant transformation have been reported. Conclusions. There is no consensus on best treatment. A multicentre study is required to identify the treatment that would reduce the recurrence rate, taking into consideration that intravesical BCG is associated with NAUB.

Clear cell adenocarcinoma of the urethra: review of the literature

Background. Clear cell adenocarcinoma of the urethra (CCAU) is extremely rare and a number of clinicians may be unfamiliar with its diagnosis and biological behaviour. Aims. To review the literature on CCAU. Methods. Various internet databases were used. Results/Literature Review. (i) CCAU occurs in adults and in women in the great majority of cases. (ii) It has a particular association with urethral diverticulum, which has been present in 56% of the patients; is indistinguishable from clear cell adenocarcinoma of the female genital tract but is not associated with endometriosis; and probably does not arise by malignant transformation of nephrogenic adenoma. (iii) It is usually, readily distinguished from nephrogenic adenoma because of greater cytological a-typicality and mitotic activity and does not stain for prostate-specific antigen or prostatic acid phosphatase. (iv) It has been treated by anterior exenteration in women and cystoprostatectomy in men and at times by radiotherapy; chemotherapy has rarely been given. (v) CCAU is aggressive with low 5-year survival rates. (vi) There is no consensus opinion of treatment options that would improve the prognosis. Conclusions. Few cases of CCAU have been reported. Urologists, gynaecologists, pathologists, and oncologists should report cases of CCAU they encounter and enter them into a multicentric trial to determine the best treatment options that would improve the prognosis.

The Application of Immunohistochemical Biomarkers in Urologic Surgical Pathology

Context

Tumors of the genitourinary tract can be diagnostically challenging, particularly in core biopsies and cystoscopic biopsies with limited material. Immunohistochemistry is a valuable tool to use when morphology alone is insufficient for diagnosis.

Objectives

To review tumors and benign lesions of the kidney, urinary bladder, prostate gland, testis, and paratesticular structures with an emphasis on difficult differential diagnoses, as well as staining patterns in normal tissue. Recommended immunohistochemical stain panels are discussed that can assist in the diagnostic workup.

Data Sources

Review of current literature.

Conclusions

Immunohistochemistry is a valuable tool, assisting in the diagnosis of problematic tumors and benign lesions of the genitourinary tract.

Nephrogenic adenoma in a urethral diverticulum

Nephrogenic adenoma (NA) is a rare finding that represents metaplasia of the urothelium. We present a case of a 46-year-old woman who presented with a symptomatic anterior vaginal wall cyst that was found to be an NA within a urethral diverticulum. Although this remains an infrequently reported entity in the literature, prevalence has been shown to be higher in consecutive case series than what may be presumed by the rarity of case reports in clinical literature. Nephrogenic adenoma within a urethral diverticulum may represent an under-recognized entity which needs to be carefully distinguished from clear cell adenocarcinoma occurring within urethral diverticula. We discuss salient clinical features of NA occurring within a urethral diverticulum and describe a review of literature of published cases to date.

Primary Clear Cell Carcinoma of the Urinary Bladder

Primary clear cell carcinoma of the urinary bladder (PCCUB) is rare. Literature review has revealed 47 cases of PCCUB which commonly affects women. The histogenesis of PCCUB is not certain and Müllerian origin and urotheilal origin have been postulated. The microscopic characteristics of PCCUB include cells with abundant clear cytoplasm, arranged in a solid, glandular, tubulocystic, or papillary pattern. The cells may be flat or cuboidal with abundant clear eosinophilic cytoplasm. Hobnailing may be evident. PCCUB, on immunohistochemistry, stain positively with pan-cytokeratin, cytokeratin 7, and CA 125. PCCUB may manifest with visible haematuria, lower urinary tract symptoms, and discharge. There is no consensus opinion regarding the best treatment option for PCCUBs and patient outcomes are not very clear. Surgery has been the adopted treatment of choice. Differential diagnoses of PCCUB include nephrogenic metaplasia, urothelial carcinoma with clear cell cytoplasm, diffuse large B-cell lymphoma, and metastatic clear cell carcinoma with the primary originating elsewhere. Conclusions. A thorough radiological imaging assessment is required in cases of PCCUB to exclude a primary tumour elsewhere. Urologists and oncologists should report cases of PCCUB they encounter and should enter them into a multicentric trial to ascertain the best management option.

Primary urethral clear-cell adenocarcinoma: comprehensive analysis by surgical pathology, cytopathology, and next-generation sequencing

Primary clear-cell adenocarcinoma of the urethra, a rare tumor that histomorphologically resembles clear-cell carcinoma of the female genital tract, occurs predominantly in women and is associated with a relatively poor prognosis. The histogenesis of this rare urethral neoplasm has not been completely resolved, but it is thought to arise from either müllerian rests or metaplastic urothelium. Herein, we present comprehensive surgical pathological and cytopathological findings from a patient with primary urethral clear-cell adenocarcinoma and describe next-generation sequencing results for this patient's unique tumor-the first such reported characterization of molecular aberrations in urethral clear-cell adenocarcinoma at the transcriptomic and genomic levels. Transcriptome analysis revealed novel gene fusion candidates, including ANKRD28-FNDC3B. Whole-exome analysis demonstrated focal copy number loss at the SMAD4 and ARID2 loci and 38 somatic mutations, including a truncating mutation in ATM and a novel nonsynonymous mutation in ALK.

Histology and immunohistochemistry of clear cell adenocarcinoma of the urethra: histogenesis and diagnostic problems

Clear cell adenocarcinoma (CCAC) of the urethra is a rare neoplasm, morphologically identical to its homologue arising in the female genital tract. The histogenesis of this neoplasm is uncertain. We present clinical, histopathologic, and immunohistochemical findings of four CCAC of the urethra and discuss the histogenesis and difficulties in diagnosis and differential diagnosis. CCAC of the urethra occurred in females (4/4). Two neoplasms were identified in urethral diverticulum; one of the two cases, in close proximity to a nephrogenic adenoma. CCAC exhibited tubulocystic, papillary, and diffuse/solid growth patterns. The neoplastic cells were cuboidal or columnar with eosinophilic or clear cytoplasm, and nuclear pleomorphism of at least moderate degree. Hobnail features and tumor necrosis were also observed. CCAC expressed p53 (4/4), AMACR (3/4), vimentin (3/4), PAX8 (2/4), CK7 (2/4), cytokeratin 34betaE12 (2/4), RCC (1/4), and CK20 (1/4) and were negative for PSA, WT1, ER, CA 125, uroplakin III, p16, and p63. The immunohistochemical profile supports a possible renal tubular cell differentiation/mesonephric origin for some urethral CCAC. Nephrogenic adenoma and metastatic clear cell carcinoma are the most important differential diagnostic considerations. Multicenter studies on more cases may improve our understanding of this malignancy.

Multifocal nephrogenic adenoma – a mimicker of malignancy

The authors report a multifocal nephrogenic adenoma of urinary bladder in an 11-y-old girl. Nephrogenic adenomas occur almost exclusively in the urinary bladder in children and are rarely multifocal. Less than 30 cases of nephrogenic adenomas have been reported in children and very few of these are multifocal. This report aims at drawing attention to this rare entity in children.

The progression of nephrogenic metaplasia of the urinary bladder to clear cell adenocarcinoma: a case report

Nephrogenic metaplasia (or nephrogenic adenoma) and clear cell adenocarcinoma of the bladder are uncommon lesions that cause diagnostic dilemmas for pathologists due to their similar morphologic features. Nephrogenic metaplasia describes a lesion in the lower urinary tract that is composed of small tubules resembling renal medullary tubules. It has been suggested that nephrogenic metaplasia may progress to clear cell adenocarcinoma but this possibility is not widely accepted. We present a case of clear cell adenocarcinoma of the bladder arising from nephrogenic metaplasia and discuss the evidence behind the association of these two distinct rare lesions.

Nephrogenic Adenoma of the Urinary Tract

Nephrogenic adenoma (NA) is an uncommon and intriguing lesion in the urinary tract. The pathogenesis of NA is not entirely clear. NA was considered to be a metaplastic process of the urothelium in response to chronic irritation of the urinary tract. However, recent evidence has shown that NA is not a metaplastic lesion but rather a proliferation of exfoliated and implanted renal epithelial cells in the urinary tract. Histologically, NAs exhibit, singly or in combination, tubules, small papillae, and microcystic structures lined by cells with little cytological atypia and focal hobnail changes. Solid formations and compressed spindled cells within a fibromyxoid background are rarely observed. Differential diagnosis includes, but is not limited to, malignant neoplasms occurring at the same sites, in particular urothelial carcinoma with deceptively bland morphology (with small tubules, microcystic and nested variants), prostatic adenocarcinoma, and clear cell adenocarcinoma. Immunohistochemical studies with antibodies targeting members of the paired box gene family (PAX2 and/or PAX8) in NAs may be helpful in the differential diagnosis of urothelial lesions and prostatic adenocarcinoma. NAs are most likely to be confused with clear cell adenocarcinoma, especially in small biopsy specimens. This is confounded by both lesions being frequently positive for PAX2, PAX8, and CK7 and not infrequently positive for p504S (α-methylacyl-CoA-racemase, AMACR) by immunohistochemistry. Recognition of its characteristic morphological patterns and awareness of its unusual architectural and cytological features are important in making the diagnosis of NA and distinguishing this lesion from its mimickers.

Primary clear cell adenocarcinoma of the bladder with recurrence: a case report and literature review

Clear cell carcinoma of the bladder is a rare tumor of the bladder. There are few reports available on this rare disease, and no cases with recurrence were reported. Here we present a case of 68-year-old woman with primary clear cell carcinoma of the bladder, who underwent repeat TUR-BT and tumor recurrence. We also reviewed the previous treatments and prognoses in previous case reports and evaluate the proper treatment for this disease. Once the diagnosis is determined, the radical surgery should be recommended. The recurrence is not prevented based on post-TUR intravesical therapy.

Adenocarcinoma of the Urinary Bladder

Primary adenocarcinoma of urinary bladder is an uncommon neoplasm and is a source of diagnostic confusion with adenocarcinomas arising in adjacent organs, especially colon. These tumors show varied histologic picture and degree of differentiation. Clinical association with bladder exstrophy and schistosomiasis has been well documented. Primary bladder adenocarcinomas have overlapping histologic and immunohistochemical features with adenocarcinomas arising from other primary sites and the suggested immunohistochemical panel includes cytokeratins 7 and 20, 34βE12, thrombomodulin, CDX2, and β-catenin. Clinical, imaging, histologic, and immunohistochemical correlation should be done while rendering this diagnosis, as prognosis and therapeutic options for primary versus metastatic adenocarcinoma vary widely.

Clear cell adenocarcinoma of urinary bladder: A case report and review

Clear cell carcinoma is an uncommon but distinct variant of urinary bladder carcinoma histologically resembling the neoplasm in the female genital tract. The histogenesis of this neoplasm is uncertain. The clinicopathologic and histologic features are suggestive of a mullerian origin in some tumors, while some believe it to be glandular differentiation of urothelium or a unique vesicular adenocarcinoma of non-mullerian origin.[1] We present a case of clear cell adenocarcinoma in a 74-year-old woman with review of literature along with its differential diagnosis.

Clinical utility of immunohistochemistry in the diagnoses of urinary bladder neoplasia

Urothelial carcinomas demonstrate diverse morphologic and immunologic features that frequently lead to diagnostic challenges. Recent advances have identified a number of immunohistochemical stains that, when used in the context of a panel, can be a valuable tool in properly classifying primary urothelial carcinoma and carcinomas secondarily involving the urinary bladder. In addition, new biomarkers prove helpful in the staging of bladder carcinoma. In this article, we review the clinical utility of immunohistochemistry in a series of diagnostic scenarios, including flat urothelial lesions with atypia, rare variants of urothelial carcinoma, primary adenocarcinoma versus secondary colorectal tumors, distinguishing prostate from urothelial carcinoma, and the utility of smoothelin in staging bladder carcinoma. Emphasis is placed on panels of commonly used biomarkers to establish diagnoses.

Hepatocyte nuclear factor-1β expression in clear cell adenocarcinomas of the bladder and urethra: diagnostic utility and implications for histogenesis

The histogenesis of clear cell adenocarcinoma of the bladder/urethra is uncertain. Hepatocyte nuclear factor-1β is a homeodomain protein that has been reported to be frequently overexpressed in ovarian clear cell adenocarcinoma in comparison with rare or no expression in other types of epithelial ovarian tumors. We assessed the expression of hepatocyte nuclear factor-1β in a series of 18 clear cell adenocarcinomas of the bladder and urethra and compared it with that of invasive high-grade transitional/urothelial carcinoma (n = 35); adenocarcinomas of the bladder, urethra, and paraurethral glands (n = 21); as well as nephrogenic adenomas of the bladder (n = 8). Staining intensity and extent were evaluated using a 4-tiered grading system (0-3). A case was considered positive for hepatocyte nuclear factor-1β if 10% or more of tumor cells showed at least weak nuclear staining or if any moderate or strong nuclear staining was observed. All 18 clear cell adenocarcinomas exhibited nuclear staining in at least 50% of tumor cells (16 strong, 1 moderate, and 1 weak with focal strong nuclear staining) in comparison with positive nuclear staining (moderate) in 1 of 21 bladder adenocarcinoma, 1 of 35 invasive high-grade transitional/urothelial carcinoma (weak to moderate staining), and 2 of 8 nephrogenic adenomas (1 weak and 1 moderate to strong staining). We concluded that hepatocyte nuclear factor-1β is a useful marker in differentiating clear cell adenocarcinomas of the bladder/urethra from invasive high-grade transitional/urothelial carcinoma and other types of bladder adenocarcinomas and to a lesser extent from nephrogenic adenomas. Hepatocyte nuclear factor-1β is of no diagnostic utility in discriminating primary bladder/urethral clear cell adenocarcinomas from metastatic clear cell adenocarcinomas of the female genital tract to the bladder/urethra. From a histogenesis standpoint, although the expression of hepatocyte nuclear factor-1β in both gynecologic and urologic tract clear cell adenocarcinomas may point to a Müllerian derivation/differentiation, this immunohistochemical evidence is insufficient to completely exclude an urothelial association.

Clear cell adenocarcinoma of the bladder and urethra: cases diffusely mimicking nephrogenic adenoma

Although clear cell adenocarcinoma have been described focally mimicking nephrogenic adenoma, we have identified a subset of clear cell adenocarcinoma that diffusely resembles nephrogenic adenoma (nephrogenic adenoma-like clear cell adenocarcinoma). Twelve classic clear cell adenocarcinomas of the bladder and urethra and 7 nephrogenic adenoma-like clear cell adenocarcinomas were compared to 10 nephrogenic adenomas. Classic clear cell adenocarcinomas and nephrogenic adenoma-like clear cell adenocarcinomas comprised 4 men and 15 women. The following features were seen in classic clear cell adenocarcinomas: nephrogenic adenoma-like clear cell adenocarcinomas: predominantly solid pattern (7/12:0/7), marked nuclear pleomorphism (7/12:1/7), prominent nucleoli (5/12:1/7), clear cytoplasm in 50% or greater of tumor (7/12:0/7), and necrosis (8/12:3/7), although the necrosis in nephrogenic adenoma-like clear cell adenocarcinomas was often focal and intraluminal. Both patterns of clear cell adenocarcinomas showed prominent hobnail features, although more pronounced in nephrogenic adenoma-like clear cell adenocarcinomas. Muscularis propria invasion was seen in 5 of 9 classic clear cell adenocarcinomas and 6 of 6 nephrogenic adenoma-like clear cell adenocarcinomas, where evaluable. Classic clear cell adenocarcinoma was associated with urothelial carcinoma (n = 2) and endometriosis (n = 1). The Ki-67 rate in clear cell adenocarcinomas ranged from 10% to 80% compared with 0% to 5% in nephrogenic adenoma. The following antibodies were not helpful in distinguishing nephrogenic adenoma-like clear cell adenocarcinoma from nephrogenic adenoma: CD10, estrogen receptor, p63, high-molecular-weight cytokeratin, and alpha-methylacyl coenzyme-A racemase. PAX2 expression was more frequent in nephrogenic adenoma (89%) compared to both patterns of clear cell adenocarcinoma (29%-32%). The key features discriminating between nephrogenic adenoma-like clear cell adenocarcinoma and nephrogenic adenoma include occasional clear cells, more prominent pleomorphism especially hyperchromatic enlarged nuclei, and extensive muscular invasion. Presence of mitoses and a high rate of Ki-67 expression in lesions resembling nephrogenic adenoma require clinical correlation, close follow-up, and repeat biopsy with more extensive sampling.

CA125-producing clear cell adenocarcinoma arising from the upper ureter and renal pelvis

Clear cell adenocarcinomas similar to those found in the female genital organs can arise in the lower urinary tract of both women and men. Clear cell adenocarcinomas occurring in the upper urinary system are exceedingly rare. Here, we present a case of clear cell adenocarcinoma arising from the upper ureter and renal pelvis of a postmenopausal woman with a ureteral stone. The patient had elevated serum levels of cancer antigen (CA) 125 (103.80 U/mL) and CA19-9 (151.96 U/mL). The tumor showed typical features of tubulopapillary structures lined with clear-to-eosinophilic cytoplasm and frequent hobnail configuration. The tumor cells were immunoreactive for cytokeratin 7, cytokeratin 20, carcinoembryonic antigen and CA125, but negative for PAX-2 and alpha-methylacyl coenzyme A racemase. Given the presence of intestinal and squamous metaplasia of the adjacent urothelium, we propose that this clear cell adenocarcinoma developed through a metaplastic process. The tumor behaved so aggressively that the patient developed multiple metastases and died of the disease 5 months after radical nephroureterectomy.

Clear-cell adenocarcinoma of vesical origin: a case study of metastatic disease treated with chemotherapy

Vesical clear cell adenocarcinoma is an uncommon tumour. The description of nearly all published cases focuses on histological issues, providing few clinical particulars and limited followup. The treatment choice is resection. No publications have been found regarding systemic treatments for advanced disease. We present a case of metastatic clear cell adenocarcinoma of the bladder treated with chemotherapy.

Clear cell adenocarcinoma of the urinary bladder: a short review

In this short review, we discuss clear cell adenocarcinoma of the urinary bladder, a rare tumor that primarily affects women. The histogenesis of this neoplasm is uncertain; in some tumors the clinicopathologic and histologic features are suggestive of a müllerian origin. Clear cell adenocarcinoma consists of cells with abundant clear cytoplasm, arranged in solid, glandular, or tubulocystic patterns. These tumors are positive for pancytokeratin, cytokeratin 7, and CA 125 immunohistochemical stains. Patients typically present with gross hematuria, dysuria, and discharge. The natural history is poorly understood and patient outcomes remain unclear. Currently, surgery is the treatment of choice. Nephrogenic adenoma is the most important differential diagnostic consideration, followed by metastatic clear cell carcinoma.

Histological variants of urothelial carcinoma: diagnostic, therapeutic and prognostic implications

It is well established that invasive urothelial carcinoma, involving the urinary bladder and renal pelvis, has marked propensity for divergent differentiation. In recent years, several 'variant' morphologies have been described and most have been recognized in the 2004 World Health Organization Classification. These histological variants of urothelial carcinoma have clinical significance at various levels, including diagnostic, that is, awareness of the morphological variant is essential in order to avoid diagnostic misinterpretations; prognostic for patient risk stratification; and therapeutic, where a diagnostic assignment of a particular variant may be associated with the administration of a therapy distinctive from that used in conventional invasive urothelial carcinoma. The diagnoses of micropapillary urothelial carcinoma, small-cell carcinoma, lymphoepithelioma-like carcinoma and sarcomatoid carcinoma are prime examples where treatment protocols may be different than the usual muscle-invasive bladder cancer. This review discusses the variants of urothelial carcinoma, outlining for each the diagnostic features, differential diagnostic considerations and the clinical significance.

Clear cell adenocarcinoma of urinary bladder and urethra: another urinary tract lesion immunoreactive for P504S

CONTEXT

Clear cell carcinoma of the urinary bladder/ urethra is a rare tumor histologically resembling the neoplasms in the female genital tract. Adequate characterization of this tumor has been hampered by its rarity. alpha-Methylacyl-CoA racemase (AMACR)/P504S has been reported to be positive in prostatic adenocarcinoma, papillary renal cell carcinoma, and gastrointestinal neoplasmas; however, it has never been studied in clear cell carcinoma of the lower urinary tract.

OBJECTIVE

To investigate the immunohistochemical staining profile in 4 primary clear cell carcinomas of the urinary tract, including P504S, which has not been previously evaluated in these tumors.

DESIGN

Four cases of clear cell adenocarcinoma were retrieved from our archives: 2 cases from the urinary bladder (one each from a man and a woman) and 2 cases from the urethra (both from women, 1 in a diverticulum). Immunohistochemistry performed on the cases were P504S, K903, cytokeratin (CK) 7, CK20, CA 125, and p63.

RESULTS

We found that clear cell carcinomas had a distinct immunoreactive profile: strongly positive for P504S, K903, and CK7, and negative for p63. Two cases were also positive for CA 125 and CK20.

CONCLUSION

The immunohistochemical profile of clear cell carcinomas shares some similarity to conventional urothelial carcinoma; however, it deviates from those tumors in being positive for P504S and negative for p63. This staining profile may suggest a nonurothelial origin for these tumors, may serve as a useful tool in the differential diagnosis of this tumor, and may reflect its etiology. Because similar expression of P504S is also seen in nephrogenic adenomas, this marker should not be used to differentiate nephrogenic adenomas from clear cell adenocarcinomas.

Expression of PAX8 in nephrogenic adenoma and clear cell adenocarcinoma of the lower urinary tract: evidence of related histogenesis?

Recent evidence has showed that nephrogenic adenoma is a true "nephrogenic" lesion derived from the proliferation of exfoliated and implanted renal tubular cells in the urinary tract, a process that closely resembles the formation of endometriosis. This new concept has led to the identification of renal transcription factor PAX2 as a diagnostic marker for nephrogenic adenoma. PAX8 is another transcription factor structurally and functionally related to PAX2. Both are cell lineage restricted transcription factors expressed in normal and neoplastic tissues of related origin, including renal tubular cells in both fetal and adult kidneys. In this study, we investigated the expression of PAX8 in nephrogenic adenoma and its mimics. We report here that PAX8 was detected in all nephrogenic adenomas (N=35) and clear cell adenocarcinoma of the lower urinary tract (N=7), but not in prostate adenocarcinoma (N=100), adenocarcinoma (N=9), squamous cell carcinoma (N=5), or urothelial carcinoma (N=48) of the urinary bladder and its variants. PAX8 was neither detected in normal urothelium of the urinary bladder nor in prostate glands and stroma. PAX2 was also detected in 2 of the 7 clear cell adenocarcinomas of the lower urinary tract. We suggest that PAX8 is an additional marker for identifying nephrogenic adenoma. Expression of PAX8 or PAX2 in both nephrogenic adenoma and clear cell adenocarcinoma of the lower urinary tract may indicate a possible related tissue origin for these 2 lesions; both may be derived from proliferating renal tubular cells in the urinary tract. In addition, detection of PAX8 or PAX2 in clear cell adenocarcinoma of the lower urinary tract is helpful in differentiating it from urothelial carcinoma and its variants and adenocarcinomas of the urinary bladder or of the prostate.

Histogenesis of clear cell adenocarcinoma in the urinary tract: evidence of urothelial origin

PURPOSE

Clear cell adenocarcinoma in the urinary tract is a rare entity with an appearance resembling its counterpart in the female genital tract. Although several theories have been proposed about its origin, its exact histogenesis has remained uncertain.

EXPERIMENTAL DESIGN

We integrated molecular genetic evaluation by fluorescence in situ hybridization and X-chromosome inactivation with conventional morphologic and immunohistochemical analyses in 12 patients with clear cell adenocarcinomas in the urinary tract.

RESULTS

Concurrent urothelial carcinoma or urothelial carcinoma in situ was present in six cases (50%) and foci of cystitis glandularis were observed in four cases (33%). Neither intestinal metaplasia nor Müllerian component was identified in any case. Cytoplasmic expression of alpha-methylacyl-CoA racemase was demonstrable in 10 of 12 tumors (83%). Moderate to diffuse immunostaining for cytokeratin 7 was identified in all 12 tumors (100%), whereas only 3 of 12 (25%) tumors showed positive immunostaining for cytokeratin 20. Focal uroplakin III staining was seen in 6 of 12 tumors (50%). In five cases (42%), focal to moderate CD10 immunoreactivity was observed. Immunostains for OCT4 and CDX2 were completely negative in all tumors. In UroVysion fluorescence in situ hybridization assays, all tumors displayed chromosomal alterations similar to those commonly found in urothelial carcinoma. Identical patterns of nonrandom X-chromosome inactivation in concurrent clear cell adenocarcinoma and urothelial neoplasia were identified in two informative female cases.

CONCLUSIONS

Our findings support an urothelial origin for most clear cell adenocarcinomas of the urinary tract, despite their morphologic resemblance to certain Müllerian-derived tumors of the female genital tract.

Nephrogenic adenoma of the ureter: case report

Nephrogenic adenoma is a rare metaplastic benign lesion of urothelium in response to genitourinary tract procedures, chronic infection, trauma, urinary calculi and immunosuppressive therapy after renal transplantation. It has been reported to occur throughout the urinary tract especially, in the urinary bladder. We report a case of nephrogenic adenoma arising from the lower end of the right ureter with clinical and radiological features suspicious of carcinoma.

A Rare Case of Clear Cell Adenocarcinoma of the Bladder with Unique Pathological Features

Clear cell adenocarcinomas of the urinary bladder are rare tumors with an unknown histogenesis. Since these tumors appear histologically similar to clear cell tumors of the female genital tract, a mullerian histogenesis has been proposed. Several publications have examined the immunohistochemical properties of clear cell adenocarcinomas to improve understanding of the cause and pathogenesis of this tumor. While specific criteria for a diagnosis of clear cell adenocarcinoma have not been defined, there are consistent staining patterns suggested for characterization. We present an important case of clear cell adenocarcinoma of the bladder with a unique staining pattern. We review the literature and discuss the differential diagnosis and various theories concerning the origin of this rare tumor.

Nephrogenic adenoma: an update on an innocuous but troublesome entity

Nephrogenic adenoma (NA) is a rare benign lesion of the urothelial tract that is typically preceded by some form of genitourinary insult. The pathogenesis of NA is not entirely clear. Although generally presumed to be a metaplastic process of the urothelium, recent evidence suggests that NA may in fact be derived from detached renal tubular cells implanting along the urothelial tract in previously injured areas, at least in cases associated with a kidney transplant. On light microscopy, NA shows a variety of patterns, including tubulocystic, papillary, and much less frequently solid, that often coexist. Recognition of its characteristic patterns, and awareness of its unusual architectural and cytologic features, is key to making the diagnosis of NA and distinguishing this lesion from malignant neoplasms occurring at the same sites, in particular, clear cell carcinoma, nested or microcystic variants of urothelial carcinoma and prostatic adenocarcinoma. Although straightforward in most cases, the correct diagnosis may be difficult to make on limited tissue samples. A number of immunohistochemical markers have been studied in an attempt to characterize NA; however, to date there is no specific immunohistochemical profile to distinguish this lesion from its malignant mimickers, although PAX2, a new marker, may prove to be helpful in this regard. Clinicopathologic correlation with careful attention to morphology remains the pillar in establishing the correct diagnosis.