The utility of p63, p40, and GATA-binding protein 3 immunohistochemistry in diagnosing micropapillary urothelial carcinoma

Reduced p63 expression is linked to unfavourable prognosis in muscle-invasive urothelial carcinoma of the bladder

Objective

There is a shortage of established prognostic biomarkers in bladder cancer. One candidate is tumour protein 63 (p63), a transcription factor of the p53 gene family that is expressed in the normal urothelium. Recently proposed RNA expression-based molecular classifiers of bladder cancer identified high p63 expression as a component of a basal/squamous subtype linked to poor patient prognosis.

Methods

In this study, p63 protein expression was analysed by immunohistochemistry on more than 2500 urothelial bladder carcinomas in a tissue microarray format to determine its relationship with clinicopathological parameters of disease progression and patient outcome.

Results

Nuclear p63 staining was seen in all cells of normal urothelium and at elevated levels in pTaG2 tumours. The rate of p63 positive cases and the staining intensity was lower in pTaG3 tumours (93.2%, p < 0.0001 for pTaG3 vs. pTaG2) and markedly lower in pT2-4 carcinomas (83.5%, p = 0.0120 for pT2-4 vs. pTaG3). Within 1018 pT2-4 carcinomas treated by cystectomy, low p63 expression was linked to nodal metastasis (p = 0.0028) and overall survival (p = 0.0005). The association with survival was independent of pT and pN (p = 0.0081). p63 expression was associated with GATA3 expression (p < 0.0001), a luminal cell type marker associated with favourable disease. A joint analysis of p63 and GATA3 did not suggest that GATA3 could provide additional prognostic information.

Conclusion

The independent prognostic role of reduced p63 expression in advanced urothelial carcinomas suggests that p63 could be a useful biomarker to distinguish pT2-4 urothelial carcinomas.

Metastatic upper tract urothelial carcinoma with nest-like features presenting as malignant pleural effusion

Metastatic urothelial carcinoma is a rare cause of pleural effusions. We report a case of urothelial carcinoma of the upper urinary tract in an oldest-old male patient, a smoker, with situs inversus totalis, that presented uniquely with malignant pleural effusion at presentation without evidence of a primary tumor on imaging. Cytological smears of the massive left pleural effusion revealed epithelioid neoplastic cells arranged in short cords, small-to-large clusters, and raspberry-like morules, mimicking mesothelioma; cell block preparations highlighted the presence of tubules and nest-like structures. The tumor cells showed a high nuclear-to-cytoplasmic ratio, nuclear grooves, and mitotic figures. Cytomorphologic features coupled with the immunophenotype of neoplastic cells (p63, GATA3, and uroplakin II positive) allowed the diagnosis of metastatic urothelial carcinoma and a possible nested subtype. These findings were supported by a total body computed tomography (CT) showing no evidence of a mass in the bladder or elsewhere in the urinary tract but a concentric parietal thickening of the proximal left ureter, suggesting malignancy. To our knowledge, a malignant effusion as a primary manifestation of urothelial carcinoma with nest-like features originating in the upper urinary tract has never been described previously. Our case focuses on the value of cell block in the working-up of neoplastic effusions by revealing the architectural pattern of an uncommon malignancy and the correlation between cytopathology and imaging gross findings to reach an accurate diagnosis.

Immunohistochemical evaluation of GATA-3 in patients with urinary bladder cancer

OBJECTIVE

Aim: To analyze expression levels of GATA-3 in bladder tumor tissues and to prove a relation between expression of GATA-3 and clinicopathological characteristics of bladder tumors, including patient age, sex, tumor grade, and muscle invasion.

PATIENTS AND METHODS

Materials and Methods: Forty formalin fixed paraffin embedded (FFPE) tissue blocks obtained from bladder tumor by transurethral resection are collected from teaching hospitals at Al-Najaf governorate. Those blocks are stained by using hematoxylin and eosin stain. Histopathological features were examined and then immunostained by GATA-3.

RESULTS

Results: Evaluation of GATA-3 expression in urothelial carcinoma, revealed GATA-3 test was (positive) in thirty-four samples of urothelial carcinoma, while GATA-3 test was (negative) in twenty-one samples of urothelial carcinoma. Correlation of GATA-3 with other variables (age, sex, and grade) was a statistically non-significant.

CONCLUSION

Conclusions: GATA-3 is an Immunohistochemical sensitive marker to diagnose urothelial carcinoma. GATA-3 expression showed non-significant relation with age, gender and histopathological parameters and its expression has been observed to be lost or reduced in substantial proportion in relation to urothelial carcinoma. This alteration or down regulation of GATA-3 is correlated with higher tumor grade and stage.

The Application and Pitfalls of Immunohistochemical Markers in Challenging Diagnosis of Genitourinary Pathology

CONTEXT.—

The morphologic features of different entities in genitourinary pathology overlap, presenting a diagnostic challenge, especially when diagnostic materials are limited. Immunohistochemical markers are valuable when morphologic features alone are insufficient for definitive diagnosis. The World Health Organization classification of urinary and male genital tumors has been updated for 2022. An updated review of immunohistochemical markers for newly classified genitourinary neoplasms and their differential diagnosis is needed.

OBJECTIVE.—

To review immunohistochemical markers used in the diagnosis of genitourinary lesions in the kidney, bladder, prostate, and testis. We particularly emphasized difficult differential diagnosis and pitfalls in immunohistochemistry application and interpretation. New markers and new entities in the 2022 World Health Organization classifications of genitourinary tumors are reviewed. Recommended staining panels for commonly encountered difficult differential diagnoses and potential pitfalls are discussed.

DATA SOURCES.—

Review of current literature and our own experience.

CONCLUSIONS.—

Immunohistochemistry is a valuable tool in the diagnosis of problematic lesions of the genitourinary tract. However, the immunostains must be carefully interpreted in the context of morphologic findings with a thorough knowledge of pitfalls and limitations.

Diagnostic and Prognostic Roles of GATA3 Immunohistochemistry in Urothelial Carcinoma

This study aimed to evaluate the diagnostic and prognostic roles of GATA-binding protein 3 (GATA3) immunohistochemistry in urothelial carcinoma (UC) using a meta-analysis. We investigated GATA3 immunohistochemical expression rates and performed a subgroup analysis based on tumor site, study location, and histological subtypes. The overall survival rates of patients with GATA3-positive and -negative UC were compared. The estimated GATA3 expression rate was 0.748 (95% confidence interval [CI]: 0.704-0.787). GATA3 expression rates in the urinary bladder and urinary tract were 0.775 (95% CI: 0.727-0.818) and 0.614 (95% CI: 0.426-0.774), respectively. The GATA3 expression rates of noninvasive and invasive UCs were 0.965 (95% CI: 0.938-0.980) and 0.644 (95% CI: 0.581-0.702), respectively. In invasive UCs, there was a significant difference in GATA3 expression between non-muscular invasion and muscular invasion subgroups (0.937, 95% CI: 0.883-0.967 vs. 0.753, 95% CI: 0.645-0.836). GATA3 expression was the highest in the microcytic subtype among the histologic subtypes (0.952, 95% CI: 0.724-0.993). There was a significant correlation between GATA3 expression and better prognosis (hazard ratio: 0.402, 95% CI: 0.311-0.521). Taken together, GATA3 expression significantly correlated with low-stage and better prognosis in UC. GATA3 expression is highly variable across histological subtypes, and one should be careful while interpreting GATA3 expression.

Pleural fluid metastasis of plasmacytoid urothelial carcinoma in comparison to micropapillary and conventional high-grade urothelial carcinoma: Cytologic and immuonohistochemical findings

Plasmacytoid urothelial carcinoma (PUC) is a rare but clinically aggressive variant of high-grade urothelial carcinoma (HGUC). Cytological features include single plasmacytoid neoplastic cells with N:C ratio around 0.5, eccentric nuclei, nuclear hyperchromasia, irregular nuclear membrane, and vacuolated cytoplasm. Micropapillary urothelial carcinoma (MPUC) is another clinically aggressive variant of HGUC that shares some overlapping features of PUC. The diagnosis of these two aggressive variants in pleural effusions can be challenging due to features mimicking adenocarcinoma, unusual immunochemistry profile, and confusion with differential diagnoses, especially when pertinent clinical information is unavailable. We present report on one case each of pleural fluid metastasis of PUC and MPUC respectively, and compare the findings with that of a metastatic conventional HGUC originally thought to be metastatic adenocarcinoma. The diagnosis of PUC was confirmed with immunohistochemical studies showing expression for cytokeratin, GATA-3, uroplakin II, and CD138, diminished or loss of E-cadherin membranous expression, negative expression for p63, p53, Epicam-BerEP4, Epicam-MOC31, and p120. The diagnosis of MPUC was confirmed with immunostain profile similar to that of PUC except positive stain for E-cadherin, p120, and p53. The diagnosis of HGUC was confirmed with immunohistochemical studies showing expression for cytokeratin, GATA-3, uroplakin II, p63, Epicam-BerEP4 (focal weak), and Epicam-MOC31. Our cases of metastatic urothelial carcinoma showed features mimicking adenocarcinoma and others, especially the MPUC and HGUC were diagnosed without prior tissue diagnosis of urothelial carcinoma. This report emphasizes the cytohistological and immunohistochemical details of urothelial carcinoma involving effusion fluid and discusses potential pitfalls in diagnosis.

Common Diagnostic Challenges and Pitfalls in Genitourinary Organs, With Emphasis on Immunohistochemical and Molecular Updates

CONTEXT.—

Lesions in the genitourinary (GU) organs, both benign and malignant, can demonstrate overlapping morphology, and practicing surgical pathologists should be aware of these potential pitfalls and consider a broad differential diagnosis for each specific type of lesion involving the GU organs. The following summary of the contents presented at the 6th Annual Chinese American Pathologists Association (CAPA) Diagnostic Course (October 10-11, 2020), supplemented with relevant literature review, exemplifies the common diagnostic challenges and pitfalls for mass lesions of the GU system of adults, including adrenal gland, with emphasis on immunohistochemical and molecular updates when relevant.

OBJECTIVE.—

To describe the common mass lesions in the GU system of adults, including adrenal gland, with emphasis on the diagnostic challenges and pitfalls that may arise in the pathologic assessment, and to highlight immunohistochemical workups and emerging molecular findings when relevant.

DATA SOURCES.—

The contents presented at the course and literature search comprise our data sources.

CONCLUSIONS.—

The diagnostic challenges and pitfalls that arise in the pathologic assessment of the mass lesions in the GU system of adults, including adrenal gland, are common. We summarize the contents presented at the course, supplemented with relevant literature review, and hope to provide a diagnostic framework to evaluate these lesions in routine clinical practice.

p63 expression in human tumors and normal tissues: a tissue microarray study on 10,200 tumors

Background

Tumor protein 63 (p63) is a transcription factor of the p53 gene family involved in differentiation of several tissues including squamous epithelium. p63 immunohistochemistry is broadly used for tumor classification but published data on its expression in cancer is conflicting.

Methods

To comprehensively catalogue p63 expression, tissue microarrays (TMAs) containing 12,620 tissue samples from 115 tumor entities and 76 normal tissue types were analyzed.

Results

p63 expression was seen in various normal tissues including squamous epithelium and urothelium. At least occasional weak p63 positivity could be detected in 61 (53%) of 115 different tumor types. The frequencies of p63 positivity was highest in squamous cell carcinomas irrespective of their origin (96–100%), thymic tumors (100%), urothelial carcinomas (81–100%), basal type tumors such as basal cell carcinomas (100%), and various salivary gland neoplasias (81–100%). As a rule, p63 was mostly expressed in cancers derived from p63 positive normal tissues and mostly not detectable in tumors derived from p63 negative cancers. However, exceptions from this rule occurred. A positive p63 immunostaining in cancers derived from p63 negative tissues was unrelated to aggressive phenotype in 422 pancreatic cancers, 160 endometrium cancers and 374 ovarian cancers and might be caused by aberrant squamous differentiation or represent stem cell properties. In 355 gastric cancers, aberrant p63 expression occurred in 4% and was linked to lymph node metastasis (p = 0.0208). Loss of p63 in urothelial carcinomas - derived from p63 positive urothelium - was significantly linked to advanced stage, high grade (p < 0.0001 each) and poor survival (p < 0.0001) and might reflect clinically relevant tumor dedifferentiation.

Conclusion

The high prevalence of p63 expression in specific tumor types makes p63 immunohistochemistry a suitable diagnostic tool. Loss of p63 expression might constitute a feature of aggressive cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-021-00260-5.

Reduced expression of GATA3 predicts progression in non-muscle invasive urothelial carcinoma of the urinary bladder

Urothelial carcinoma (UC) of the urinary bladder is the ninth most common cancer worldwide. The majority of these patients present with non-muscle invasive bladder cancer (NMIBC). GATA3 has recently emerged as one of the diagnostically helpful immunohistochemical markers for UC. The published literature, however, lacks comprehensive studies on the impact of GATA3 expression on the prognosis of UC patients. This study evaluated and statistically analyzed the immunohistochemical expressions of GATA3 and Ki67 in 50 Egyptian patients with NMIBC and correlated the markers' expressions with clinicopathological variables and patients' outcome. Ten control cases were included. The expressions of GATA3 and Ki67 were significantly downregulated and upregulated respectively in UC cases compared to the control group. GATA3 down-expression was significantly associated with high grade tumors and tumor progression with 72% prediction accuracy. Higher proliferative activity was significantly correlated with high grade, non-papillary growth pattern, and lamina propria invasion. The predictive performance of GATA3 and Ki67 in predicting malignancy and tumor grade was good. We concluded that GATA3 downregulation and increased proliferative activity might be implicated in UC tumorigenesis, loss of differentiation, and aggressiveness. Reduced GATA3 expression could predict progression in NMIBC with an accuracy of 72% and thus it constitutes a potentially promising novel prognostic marker in patients with urothelial carcinoma.

Cutaneous Metastases: A Review and Diagnostic Approach to Tumors of Unknown Origin

CONTEXT.—

Cutaneous metastases from a distant malignancy are a diagnostic challenge for pathologists. Secondary involvement of the skin by a metastatic process portends a much worse clinical prognosis than any primary cutaneous malignant mimickers. Immunohistochemical staining methods continue to evolve and are of paramount importance in diagnosis.

OBJECTIVE.—

To review the clinical, histopathologic, and immunohistochemical staining patterns for commonly encountered entities and discuss potential pitfalls in diagnosis. A practical guide useful in approaching cutaneous metastases of unknown primary is outlined.

DATA SOURCES.—

An extensive search and review of literature in PubMed was performed, processed, and condensed.

CONCLUSIONS.—

Cutaneous metastases have broad histopathologic patterns. They are nearly always dermal based, with an overall foreign appearance. They can be single papules/nodules or multiple in number, mimicking an inflammatory or infectious process. Ultimately, immunohistochemistry remains an essential diagnostic tool, and clinical correlation is paramount in the workup of these entities.

Cell Polarity Reversal Distinguishes True Micropapillary Growth From Retraction Artifact in Invasive Urothelial Carcinoma

Focal micropapillary features in invasive urothelial carcinoma is sometimes difficult to distinguish from retraction artifact morphologically. Cell polarity reversal has been demonstrated in micropapillary tumors by epithelial membrane antigen (EMA) immunostaining. We have previously described the use of E-cadherin as a cell polarity marker in ovarian micropapillary serous borderline tumors. The aim of this study was to evaluate the utility of immunohistochemistry for EMA and E-cadherin in differentiating micropapillary urothelial carcinoma from retraction artifact. We identified 29 invasive urothelial carcinomas with micropapillary features and 30 invasive urothelial carcinomas without reported micropapillary features but with areas of retraction artifact. Cell polarity reversal was considered present if E-cadherin showed membranous apical cup-like staining or if EMA demonstrated a well-defined basal staining towards the stroma. Twenty-seven of 29 cases (93%) of urothelial carcinoma with micropapillary features demonstrated EMA or E-cadherin staining patterns consistent with cell polarity reversal. Staining consistent with micropapillary architecture was identified with both markers in 20 of these 27 cases (74%). Six cases showed reversal of polarity by E-cadherin alone, whereas 1 case showed polarity reversal by EMA alone. Retraction artifacts showed circumferential staining by E-cadherin and lacked well-defined basal staining by EMA. Three cases originally classified as with retraction artifact showed reversal of cell polarity by both EMA and E-cadherin and were reclassified as micropapillary. Our data show that pathologists can reliably make this distinction in most cases. However, in some cases with ambiguous features, EMA and E-cadherin immunostaining may aid in resolving this diagnostic dilemma.

Importance of identification of prostatic adenocarcinoma in urine cytology

BACKGROUND

Prostate carcinoma (PCa) occasionally involves the urethra and/or bladder. In these cases, PCa cells may be detected in urine. The purpose of this study was to describe the salient cytomorphologic, immunocytochemical, and epidemiologic features of PCa cells detected in urine cytology slides via a retrospective case series review.

MATERIALS AND METHODS

We retrospectively identified 28 cases with urine cytology either suspicious or positive for PCa. Clinical and histopathologic data were reviewed.

RESULTS

We identified 23 prostatic acinar adenocarcinomas (PAAs) and 5 prostatic adenocarcinomas with ductal features (PDAs). Urine cytology was the first evidence of disease in 6 (26%) patients with PAA and in 4 (80%) of the patients with PDA. In patients with PAA, 17 had a previous history of PAA, with positive urine cytology in the setting of disease recurrence or persistence within the bladder or urethra. The PAA in urine presented as single or small clusters of atypical cuboidal glandular cells with large, eccentric, round, or oval uniform nuclei containing conspicuous nucleoli, and scant to moderate delicate or granular cytoplasm, whereas the PDA presented as atypical columnar glandular cells in flat nests or 3-dimensional clusters, and with prominent nucleoli.

CONCLUSIONS

Using standard urine cytology, we were able to detect PCa cells in the urine. Although rare, PCa was first diagnosed by urine cytology in select cases, with a higher frequency in patients with PDA. Clinicians should be aware that PCa cells can be identified by urine cytology as this can lead to an earlier diagnosis and treatment.

Urothelial tumors with villous morphology: Histomorphology and role of immunohistochemistry in diagnosis

Villous adenoma and urothelial carcinoma with villoglandular differentiation (UCVGD) are rare urothelial tumours showing villous morphology, the former being a preneoplastic entity and the latter being a malignant one. The detailed immunohistochemistry of these entities is previously not described in the literature. Moreover, a limited biopsy sample of UCVGD or a villous adenoma with or without adenocarcinoma may be difficult to distinguish on the basis of the histomorphology alone. An immunohistochemical panel comprising of GATA3, p63, β-catenin, CK7 and CK20 was performed on five cases of UCVGD and three cases of villous adenoma with the aim of studying the expression of the proteins thereby aiding in the diagnosis of these entities in a limited surgical pathology specimen. The mean age of UCVGD was 66.8 years and all the patients were male. All the cases of UCVGD were associated with high grade papillary urothelial carcinoma with lamina propria invasion. The immunohistochemical panel showed strong nuclear GATA3 expression in the urothelial component of UCVGD. Interestingly, the high grade and the low grade villoglandular components of UCVGD also expressed GATA3 (nuclear) with a progressive loss of expression from the high grade to the low grade component. The villous adenomas showed negativity or aberrant cytoplasmic positivity for GATA3. The β-catenin showed a gradual loss of membranous expression from villous adenoma to low grade and high grade villoglandular components of UCVGD with a patchy membranous expression in the urothelial component of the UCVGD. p63 showed strong nuclear positivity in the urothelial component and uniform negativity in the villous adenoma and villoglandular component of UCVGD irrespective of its grade, thereby distinguishing the villoglandular component from the urothelial component. The urothelial component of UCVGD showed strong membranous CK7 expression and was higher than the CK20 expression in the urothelial component. In contrast, CK20 expression was higher in villous adenoma as compared to CK7. There was no difference in the expression of CK7 and CK20 in the villoglandular components and low grade and high grade villoglandular areas. The above-mentioned immunohistochemical pattern may help to distinguish the UCVGD from the villous adenoma.

The Utility of GATA3 in the Diagnosis of Urothelial Carcinomas With Variant Morphologic Patterns

The transcription factor GATA3 is a recently described biomarker that is highly expressed in bladder and breast carcinomas. Although it has shown sensitivity as a marker of primary bladder carcinomas with purely urothelial differentiation, the ability of GATA3 to label primary bladder carcinomas with variant morphologic patterns has been incompletely assessed to date. The current study was designed to determine whether GATA3 staining is retained in "unconventional" bladder carcinomas. Eighty-eight cases of primary bladder cancers were retrieved from the authors' institutional archive, and they included the following histomorphologic types: 6 small cell carcinomas, 12 sarcomatoid carcinomas, 17 adenocarcinomas (both primary and urothelial variants with glandular differentiation), 24 micropapillary carcinomas, and 27 squamous cell carcinomas (both primary and urothelial variants with squamous differentiation). A tissue microarray was constructed and automated immunostaining for GATA3 (Clone L50-823, Biocare Medical, Concord, CA) was performed using standard technique. Among the 5 variants of unconventional bladder carcinoma, only the micropapillary and sarcomatoid forms exhibited consistent and strong immunolabeling for GATA3. Hence, the sensitivity of this determinant is diminished in several histologic forms of primary bladder carcinoma. That fact will affect the interpretation of GATA3 stains in the context of possible metastasis from primary bladder carcinomas with variant morphologic patterns, as well as their distinction from secondary bladder involvement by tumors of nonurothelial origin.

Falling under the umbrella cells: A single institutional experience and literature review of urothelial carcinoma presenting as a primary pancreatic mass on endoscopic ultrasound-guided fine-needle aspiration

Metastases to the pancreas are much less common than primary pancreatic lesions, and there are few reports in the literature of metastatic urothelial carcinoma (UC) found in the pancreas. We report two cases of metastatic UC mimicking a primary pancreatic lesion. Two female patients, aged 48 and 83 years, presented with isolated pancreatic lesions causing obstructive jaundice suspicious for pancreatic adenocarcinoma and underwent endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) with rapid on-site evaluation (ROSE). On cytopathology, the lesions were found to be UC, confirmed with immunohistochemical (IHC) staining. UC rarely metastasizes to the pancreas, and diagnosis through EUS-FNA can be challenging. However, the utilization of ROSE, dedicated cell block passes, and IHC have proved to be effective in obtaining this unusual pancreatic diagnosis by EUS-FNA.

TERT promoter mutation status in sarcomatoid urothelial carcinomas of the upper urinary tract

AIM

To determine TERT promoter mutation status as well as the expression of PAX8, GATA3, p63, p40, p53 and uroplakin III in 17 patients with the upper urinary tract sarcomatoid urothelial carcinoma.

METHODS & RESULTS

 TERT C228T mutations were found in six of 17 cases (35%). p53 was expressed in 77% of these tumors. PAX8, GATA3, p40 and uroplakin III are less frequently expressed. Lymph node metastases were present in ten cases (59%). Eight patients (47%), including all three patients with TERT mutation, died of cancer within 2 years after surgery.

CONCLUSION

Sarcomatoid carcinoma of the upper urinary tract is an aggressive tumor and the presence of TERT mutation may portend poor prognosis.

Utility and pitfalls of GATA3 immunocytochemistry for diagnosis of metastatic breast carcinoma and urothelial carcinoma on cytology specimens

INTRODUCTION

Although GATA3 expression has been studied extensively on histology specimens and has demonstrated a high level of accuracy in detecting carcinomas from breast or urothelial origin, its utility on cytology samples, especially the influence of different sample (fine-needle aspiration [FNA] versus effusion fluid) and preparation (cell block versus smear) on the staining, is understudied.

MATERIALS AND METHODS

We retrospectively searched our institution's pathology database for cytologic cases where GATA3 immunostaining was performed during diagnostic workup and identified a total of 178 cases, consisting of 89 metastatic breast carcinomas, 22 metastatic urothelial carcinomas, and 67 malignant neoplasms of other origin. Frequency of GATA3 expression was evaluated in each group.

RESULTS

For metastatic breast carcinomas, 75% expressed GATA3; 74% on FNA samples and 77% on fluid samples; 71% on cell block and 89% on smear. GATA3 was positive in 44% triple-negative breast carcinomas. Of the 22 metastatic urothelial carcinomas (21 FNA samples and 1 fluid; 21 cell blocks and 1 smear), all were positive for GATA3. Of the 67 malignancies of other origin, 4 (6%) were positive for GATA3 (ie, a metastatic ovarian serous carcinoma, a metastatic squamous cell carcinoma, a recurrent poorly differentiated skin adnexal carcinoma, and a metastatic thymic carcinoma).

CONCLUSIONS

GATA3 is a useful biomarker for detecting carcinomas of breast or urothelial origin on cytologic specimens. It may detect breast cancers with the triple-negative phenotype. Both cell block and smear preparations can be reliably used for the staining. GATA3-positive immunostaining is occasionally seen in other tumors, which may cause diagnostic confusion.

Diagnostic utility of double immunostaining of a urine cytology preparation for cytokeratin 20/p53 expression in a young woman with micropapillary urothelial carcinoma of the renal pelvis presenting as an unknown primary malignancy

Atypical urine cytology (CYT) triggers a cystoscopic or another ancillary investigation that targets urothelial neoplasms. We report a case presenting as an unknown primary malignancy, which illustrated the diagnostic utility of direct double immunostaining for cytokeratin 20 (CK20)/p53 expression in a urine CYT specimen. A 42-year-old woman visited the emergency room for pain in her right lower abdominal quadrant. Computed tomography revealed postrenal obstructive hydronephrosis, and her urine CYT showed malignancy, type undetermined. Atypical cells that are positive for cytoplasmic expression of CK20 and nuclear expression of p53 could facilitate the decision to perform a nephroureterectomy for urothelial carcinoma.