Mimickers of urothelial neoplasia

Expression of L1 Cell Adhesion Molecule, a Nephronal Principal Cell Marker, in Nephrogenic Adenoma

Nephrogenic adenoma (NA) is a benign, reactive lesion seen predominantly in the urinary bladder and often associated with antecedent inflammation, instrumentation, or an operative history. Its histopathologic diversity can create diagnostic dilemmas and pathologists use morphologic evaluation along with available immunohistochemical (IHC) markers to navigate these challenges. IHC assays currently do not designate or specify NA's potential putative cell of origin. Leveraging single-cell RNA-sequencing technology, we nominated a principal (P) cell-collecting duct marker, L1 cell adhesion molecule (L1CAM), as a potential biomarker for NA. IHC characterization revealed L1CAM to be positive in all 35 (100%) patient samples of NA; negative expression was seen in the benign urothelium, benign prostatic glands, urothelial carcinoma (UCA) in situ, prostatic adenocarcinoma, majority of high-grade UCA, and metastatic UCA. In the study, we also used single-cell RNA sequencing to nominate a novel compendium of biomarkers specific for the proximal tubule, loop of Henle, and distal tubule (DT) (including P and intercalated cells), which can be used to perform nephronal mapping using RNA in situ hybridization and IHC technology. Employing this technique on NA we found enrichment of both the P-cell marker L1CAM and, the proximal tubule type-A and -B cell markers, PDZKI1P1 and PIGR, respectively. The cell-type markers for the intercalated cell of DTs (LINC01187 and FOXI1), and the loop of Henle (UMOD and IRX5), were found to be uniformly absent in NA. Overall, our findings show that based on cell type-specific implications of L1CAM expression, the shared expression pattern of L1CAM between DT P cells and NA. L1CAM expression will be of potential value in assisting surgical pathologists toward a diagnosis of NA in challenging patient samples.

Adenocarcinomas of the Gynecologic Tract Involving the Urinary Bladder: A Series of 16 Cases Potentially Mimicking Urothelial Malignancy

CONTEXT.—

There is limited literature describing gynecologic adenocarcinomas involving the urinary bladder and potential diagnostic pitfalls.

OBJECTIVE.—

To describe key features distinguishing metastatic (or extension of) gynecologic adenocarcinomas from urothelial carcinomas with glandular differentiation.

DESIGN.—

Retrospective review of surgical pathology cases of gynecologic adenocarcinomas involving the bladder from 2 different institutions, retrieved from surgical pathology archives, was performed. Morphologic features were recorded, along with immunohistochemistry results when available. Electronic medical records were reviewed for clinical and radiographic information.

RESULTS.—

Sixteen cases of gynecologic adenocarcinomas (9 endometrial endometrioid adenocarcinomas, 4 endometrial serous carcinomas, 2 high-grade tubo-ovarian serous carcinomas, and 1 cervical adenosquamous carcinoma) involving the bladder were identified. All included cases had mucosal involvement potentially mimicking primary bladder neoplasms, including 4 cases originally diagnosed as urinary carcinomas. Tumors expressed keratin 7 (12 of 13; 92%), PAX8 (11 of 12; 92%), estrogen receptor (11 of 15; 73%), p16 (8 of 11; 73%), progesterone receptor (8 of 14; 57%), GATA3 (5 of 12; 42%), and p63 (3 of 11; 27%); all tumors were negative for keratin 20 (0 of 12). Features supportive of Müllerian origin included prior history of gynecologic malignancy, lack of morphologic heterogeneity in nonendometrioid tumors, and immunophenotypic coexpression of PAX8 and estrogen receptor with absent GATA3. Potential pitfalls seen in a subset of cases included misleading radiologic and cystoscopic findings, replacement of the overlying urothelial mucosa by tumor mimicking precursor lesions, focal GATA3 and/or p63 positivity, and areas of squamous differentiation in tumors of endometrioid histology.

CONCLUSIONS.—

A combination of clinical history, certain morphologic features, and proper selection of immunohistochemical stains is key for the correct diagnosis of secondary gynecologic adenocarcinomas involving the urinary bladder.

[Mimickers and diagnostic pitfalls of urinary bladder cancer]

Urothelial carcinoma (UC) is by far the most common malignant neoplasm of the urinary bladder; however, there are both benign and malignant changes of the urothelium which morphologically resemble urothelial carcinomas or other carcinomas of the urinary bladder. Thus, these mimickers can cause problems in the histomorphological diagnosis. This article provides an overview of possible mimickers and pitfalls of bladder cancer as well as practical notes on the diagnostic procedure, partly using case studies.

Eosinophilic cystitis mimicking bladder tumor: A case report

Eosinophilic cystitis (EC) is a rare inflammatory condition characterized by eosinophilic infiltration into the bladder wall. It often presents symptoms common to urological issues such as urinary tract infections, hematuria, bladder stones, or bladder neoplasms. Here, we describe a case of a 44-year-old male veteran with a history of multiple tuberculosis episodes who presented to the Emergency Department with dysuria, suprapubic pain, and gross hematuria. Initial imaging and cystoscopy concerned bladder neoplasia; however, subsequent pathological evaluation showed EC. This case underscores the importance of considering EC in the differential diagnosis of bladder tumors, especially when imaging describes bladder wall thickening in a patient without risk factors for bladder malignancy.

Tumefactive Nonneoplastic Proliferative Pseudotumors of the Kidneys and Urinary Tract: CT and MRI Findings with Histopathologic Correlation

A diverse spectrum of pathologically distinct, nonneoplastic, proliferative conditions of the kidneys and urinary tract demonstrate a expansile growth pattern similar to that of neoplasms. The renal pseudotumors include myriad causes of infections as well as rare noninfectious causes such as sarcoidosis, amyloidosis, and immunoglobulin G4-related disease (IgG4-RD). Rare entities such as cystitis cystica, endometriosis, nephrogenic adenoma, and pseudosarcomatous myofibroblastic proliferation and distinct types of prostatitis comprise tumefactive nontumorous disorders that affect specific segments of the urinary tract. The pseudotumors of the kidneys and urinary tract demonstrate characteristic histopathologic and epidemiologic features, as well as protean clinical manifestations, natural history, and imaging findings. Many patients present with genitourinary tract-specific symptoms or systemic disease. Some cases may be incidentally discovered at imaging. Some entities such as perinephric myxoid pseudotumors, IgG4-RD, fibroepithelial polyp, and nephrogenic adenoma display specific anatomic localization and disease distribution. Imaging features of multisystem disorders such as tuberculosis, sarcoidosis, and IgG4-RD provide supportive evidence that may allow precise diagnosis. Fungal pyelonephritis, xanthogranulomatous pyelonephritis, IgG4-RD, actinomycosis, and endometriosis show markedly low signal intensity on T2-weighted MR images. Although some pseudotumors exhibit characteristic imaging findings that permit correct diagnosis, laboratory correlation and histopathologic confirmation are required for definitive characterization in most cases. A high index of suspicion is a prerequisite for diagnosis. Accurate diagnosis is critical for instituting optimal management while preventing use of inappropriate therapies or interventions. Surveillance CT and MRI are frequently used for monitoring the response of pseudotumors to therapy. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Fibromyxoid Nephrogenic Adenoma: A Series of 43 Cases Reassessing Predisposing Conditions, Clinical Presentation, and Morphology

Nephrogenic adenoma is a benign epithelial lesion of the genitourinary tract that arises from the reimplantation and proliferation of shed renal tubular cells in areas of urothelial injury and denudation. Fibromyxoid nephrogenic adenoma is a rare variant that consists of compressed spindle-shaped renal epithelial cells in a fibromyxoid background. Only 14 observations of this variant are reported in the literature. We performed a retrospective analysis of fibromyxoid nephrogenic adenomas from 3 large reference centers. We identified 43 lesions in 6 women and 36 men (2 in 1 man) with a median age of 72 years (range, 31 to 94 y). Median lesion size was 0.7 cm (range, 0.2 to 5 cm). Nephrogenic adenomas were in the bladder (n=15), prostate/prostatic urethra (n=14), kidney (n=7), ureter (n=3), penile urethra (n=3), and urethral diverticulum (n=1). One of the kidney lesions developed in an end-stage kidney and radiologically mimicked cancer. Of 37 patients with information, 36 had predisposing conditions including prior biopsy, transurethral resection of bladder tumor, resection, Foley catheter, BCG treatment, urinary stones, (chemo)radiation, or diverticulum. Only 4/37 (10.8%) had a history of prior irradiation. Fifteen lesions had pure fibromyxoid morphology and 28 were admixed classic and fibromyxoid patterns. Three nephrogenic adenomas involved prostatic stroma, 3 renal sinus fat, 2 muscularis propria (1 bladder, 1 renal pelvis), 1 perinephric fat, and 1 corpus spongiosum. Ten fibromyxoid nephrogenic adenomas were intermixed with urothelial carcinoma, 1 with prostate adenocarcinoma, and 1 with malignant melanoma. By immunohistochemistry, PAX8 was positive in all the examined lesions (n=31). Napsin A was negative in all examined fibromyxoid nephrogenic adenomas (n=30). Twenty of them had classic nephrogenic adenoma component which was positive for napsin A. Similar to classic nephrogenic adenoma, fibromyxoid nephrogenic adenoma can occur anywhere along the urinary tract and is associated with a prior history that causes urothelial injury. In nearly a quarter of the cases, fibromyxoid nephrogenic adenoma extended beyond the lamina propria. Unlike previously suggested, fibromyxoid nephrogenic adenoma is not specifically related to prior radiation therapy. Awareness of this variant is important to avoid misdiagnosis and overtreatment.

[S2k guidelines for the diagnosis and treatment of endometriosis-Recommendations for pathology]

Die vorliegende Übersicht fasst die relevanten Aspekte der S2k-Leitlinie Endometriose zusammen. Die Empfehlungen umfassen die Aufarbeitung und Befunderhebung bei Biopsien und Resektaten, die bei der klinischen Diagnose einer Endometriose entnommen wurden. Die Leitlinie berücksichtigt neben praktischen Aspekten der Pathologie ebenso die klinischen Notwendigkeiten an die Histopathologie für eine optimale Diagnostik und Therapie der Patientinnen.

Basierend auf der in der pathologischen Literatur gebräuchlichsten Definition der Endometriose des Corpus uteri (Adenomyosis uteri) wurde diese in der Leitlinie definiert als der Nachweis des Endometrioseherdes im Myometrium in einem Abstand zur endomyometranen Grenze von einem mittelgroßen Gesichtsfeld (100fache Vergrößerung), was metrisch rund 2,5 mm entspricht. Bei Darmresektaten soll zum Status der Resektionsränder Stellung genommen werden.

Ebenso definiert werden Anforderungen im Kontext endometrioseassoziierter Karzinome (z. B. Hormonrezeptorbestimmungen, immunhistochemische Untersuchung auf Ausfall der DNA-Mismatch-Reparaturproteine).

Safety and efficacy of holmium laser enucleation of prostate as salvage procedure for persistent or recurrent lower urinary tract symptoms secondary to bladder outlet obstruction after prior prostate artery embolization: a match analysis

PURPOSE

To evaluate safety and efficacy of Holmium laser enucleation of Prostate (HoLEP) for management of persistent or recurrent lower urinary tract symptoms after prior prostate artery embolization (PAE). We also evaluated histopathological changes in prostate after PAE.

METHODS

Ten patients who underwent HoLEP after prior PAE were matched according to age, weight of resected prostate tissue, and anticoagulation status in 1:2 ratio with patients who underwent HoLEP without prior PAE by a researcher who was blinded to patient's outcome at the time of matching. Histopathological examination of prostate tissue was performed to look for changes related to prior PAE. Patient's demographics, perioperative parameters, and follow-up data were retrospectively compared.

RESULTS

The median interval between PAE and HoLEP was 25 months [IQR 14.5-37.5]. Patients demographic were comparable in both groups. Intra-operatively plane of enucleation were well-maintained in spite of prior PAE. The differences in duration of surgery, enucleation efficiency, hemoglobin drop, duration of catheterization and hospital stay, and complications were statistically insignificant. Incidental prostate cancer was identified in 10% specimens from both groups. Post-PAE prostate specimens demonstrated evidence of remote-healed infarction represented by dense hyalinized paucicellur connective tissue with surrounding squamous metaplasia. There were no statistically significant differences in AUA symptom scores, maximum urine flow rate, post-void residual urine volume, and PSA at 3- and 6-month follow-up between both groups.

CONCLUSIONS

Plane of enucleation is well-maintained after prior PAE. Salvage HoLEP is safe and effective after previous PAE and provide outcome comparable with HoLEP as a primary procedure.

Expression of uroplakin II and GATA-3 in bladder cancer mimickers: caveats in the use of a limited panel to determine cell of origin in bladder lesions

Antibodies targeting uroplakin II (UPII) are highly specific for urothelial cells and are frequently used to determine if a primary bladder lesion or a metastatic lesion originates from the urothelium. However, to date, no studies have tested the expression of UPII in histological mimickers of bladder cancer that are nonurothelial in origin. Given the potential risk of misdiagnosis, immunohistochemical markers are often used to better characterize these lesions. In the present study, we analyzed the immunohistochemical expression of UPII in a set of urothelial carcinoma mimickers that included conventional nephrogenic adenoma (n = 8), papillary nephrogenic adenoma (n = 6), endometriosis/endosalpingiosis (n = 5), inflammatory myofibroblastic tumor (n = 4), ectopic prostate tissue (n = 2), and malakoplakia (n = 2). We also examined the expression of GATA-3, another commonly used immunohistochemical marker in bladder cancer diagnosis, in the same lesions. Weak immunoreactivity for UPII was identified in 6 of 27 mimickers (22%), and GATA-3 was expressed in 16 of 27 mimickers (59%). Strong immunoreactivity for UPII appeared to be a specific marker for urothelial cell of origin, although weak staining was seen in a significant proportion of mimickers. GATA-3 immunostaining was present in a greater number and broader spectrum of mimickers; however, only one case of papillary nephrogenic adenoma showed dual positivity for UPII and GATA-3. These findings support the immunohistochemical panel-based approach in the diagnosis of bladder lesions, especially if nonurothelial bladder cancer mimickers are in the differential diagnosis. Additional larger studies would be of value to expand on these findings.

Mimickers of Urothelial Carcinoma and the Approach to Differential Diagnosis

A broad spectrum of lesions, including hyperplastic, metaplastic, inflammatory, infectious, and reactive, may mimic cancer all along the urinary tract. This narrative collects most of them from a clinical and pathologic perspective, offering urologists and general pathologists their most salient definitory features. Together with classical, well-known, entities such as urothelial papillomas (conventional (UP) and inverted (IUP)), nephrogenic adenoma (NA), polypoid cystitis (PC), fibroepithelial polyp (FP), prostatic-type polyp (PP), verumontanum cyst (VC), xanthogranulomatous inflammation (XI), reactive changes secondary to BCG instillations (BCGitis), schistosomiasis (SC), keratinizing desquamative squamous metaplasia (KSM), post-radiation changes (PRC), vaginal-type metaplasia (VM), endocervicosis (EC)/endometriosis (EM) (müllerianosis), malakoplakia (MK), florid von Brunn nest proliferation (VB), cystitis/ureteritis cystica (CC), and glandularis (CG), among others, still other cellular proliferations with concerning histological features and poorly understood etiopathogenesis like IgG4-related disease (IGG4), PEComa (PEC), and pseudosarcomatous myofibroblastic proliferations (post-operative spindle cell nodule (POS), inflammatory myofibroblastic tumor (IMT)), are reviewed. Some of these diagnoses are problematic for urologists, other for pathologists, and still others for both. Interestingly, the right identification of their definitory features will allow their correct diagnoses, thus, avoiding overtreatment. The literature selected for this review also focuses on the immunohistochemical and/or molecular data useful to delineate prognosis.

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).

Quantitative Analysis of Enhanced Computed Tomography in Differentiating Cystitis Glandularis and Bladder Cancer

Objective

This study was performed to assess the value of quantitative analysis of enhanced computed tomography (CT) values in the differential diagnosis of bladder cancer and cystitis glandularis (CG).

Methods

Eighty patients with bladder masses (39 with CG and 41 with bladder cancer) who underwent enhanced CT were retrospectively reviewed. The CT enhancement values of the lesion and normal bladder wall in the arterial phase, venous phase, and delayed phase were measured. The relative enhancement CT values (relative enhancement CT value = enhancement CT value of lesion - enhancement CT value of normal bladder) in the arterial phase, venous phase, and delayed phase were also calculated. The pathological results were used as the gold standard, and the area under the curve (AUC), sensitivity, and specificity were calculated for the six groups of quantitative indicators (enhanced CT values and relative enhanced CT values of CG and bladder cancer in the arterial, venous, and delayed phases). We performed the leave-group-out cross-validation method to validate the accuracy, AUC, sensitivity, and specificity. The differences in accuracy, AUC, sensitivity, and specificity among the six groups of quantitative indicators were compared by the t-test.

Results

In a combined analysis of the AUC, sensitivity, and specificity performance, the best indicator was the arterial-phase relative enhancement CT value with a cut-off of 25.85 HU (AUC, 0.966; sensitivity, 95.1%; specificity, 92.3%). We used the 100-times leave-group-out cross-validation method to validate the accuracy, AUC, sensitivity, and specificity. Arterial-phase relative enhancement CT values showed the highest AUC and accuracy among the six groups, with statistical significance (P < 0.05).

Conclusion

Quantitative analysis of enhanced CT is of great clinical value in the differential diagnosis of CG and bladder cancer.

The Paris System "atypical urothelial cells" category: can the current criteria be improved?

INTRODUCTION

The Paris System (TPS) for reporting urine cytology was developed for standardization of diagnosis focusing on the detection of high-grade urothelial carcinoma (HGUC). Probably the most challenging task for TPS is to provide criteria for the atypical urothelial cell (AUC) category. The TPS criteria for AUC include increased nuclear/cytoplasmic (N/C) ratio (>0.5) and 1 of the 3 minor criteria including nuclear hyperchromasia (NH), coarse chromatin (CC) and irregular nuclear membrane (INM). We evaluated TPS-AUC diagnostic value and investigated whether other morphologic parameters can improve its criteria.

MATERIALS AND METHODS

Urine samples with diagnoses of AUC collected during a 6-month period were re-reviewed. Data captured included N/C ratio >0.5, NH, CC, INM, and 2 additional criteria including enlarged nuclear size (ENS) and the presence of nucleolus (N). ENS was considered when the nucleus was 2 times larger than the urothelial cell or 3 times larger than lymphocyte.

RESULTS

By applying the TPS-AUC criteria, the rate of atypia diagnosis reduced in comparison to Pre-TPS (9% versus 13%, P = 0.02). Among the AUC minor criteria, NH was the best criterion with the highest interobserver agreement (IOA) and correlation with HGUC (k = 0.342, r = 0.61, P < 0.001) and strong PPV (93.6%). ENS had the highest PPV (95.8%) and, after NH, had the highest IOA and correlation with HGUC (k = 0.29, r = 0.52, P < 0.001).

CONCLUSION

TPS improves the diagnostic value of urine cytology, particularly in cases with atypia. ENS is a strong criterion for increasing the diagnostic value of AUC and potentially can improve TPS performance as a minor criterion.

Villous Morphology in Urinary Bladder Biopsy: An Approach to Diagnosis

Villous morphology in urinary bladder biopsy is a relatively uncommon finding. Villi are slender, finger-like structures that are commonly seen in the small intestine or in neoplastic lesions of gastrointestinal lineage/differentiation. Importantly, placenta also exhibits villi that are morphologically and functionally different from the intestinal one. Majority of the neoplastic lesions of urinary bladder are urothelial in origin with a minor subset showing glandular differentiation. While the presence of benign villi in urinary bladder biopsy necessitates a search for an occult perforation, provided a sample mismatch is ruled out, cytoarchitecturally abnormal/dysplastic villi indicate a neoplastic lesion of the urinary bladder encompassing villous adenoma and adenocarcinoma and urothelial carcinoma with villoglandular differentiation. The dysplastic villi in urinary bladder also imply a lower gastrointestinal endoscopy to rule out a colorectal primary. The development of the villous lesions in the urinary bladder and the colorectum are embryologically related and pose a major diagnostic challenge to the clinicians and surgical pathologists due to identical histomorphology and immunohistochemistry. We tend to discuss the morphological differentials and diagnostic approach to the villous lesions in the urinary bladder biopsy.

Common and uncommon features of nephrogenic adenoma revisited

Nephrogenic adenoma is a common diagnosis in urological pathology that may be challenging for general pathologists. Due to its polymorphic appearance under the microscope, some cases can be misdiagnosed as malignancy and then unnecessarily overtreated. Aside from the typical tubules, cysts and papillae, nephrogenic adenoma may display a broad spectrum of histologic appearances and locations, some of them atypical or unexpected. These unusual and concerning features will have special consideration in this description. The goal of the review is to increase awareness of general pathologists of the varied histology of nephrogenic adenoma.