Nested variant of urothelial carcinoma: a clinicopathologic and immunohistochemical study of 30 pure and mixed cases

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.

Pseudocarcinomatous Hyperplasia of the Urinary Bladder

We review the morphology and differential diagnoses of pseudocarcinomatous hyperplasia of the bladder, using a study case to illustrate the discussion. Pseudocarcinomatous hyperplasia is a rare, reactive response to an ischemic insult, classically to radiation therapy, and consists of proliferative, pseudoinfiltrative urothelial nests within the stroma. The presence of background radiation therapy–related changes, such as numerous dilated thrombosed vessels, reactive-appearing endothelial and stromal cells, edema, and hemorrhage, can provide clues to the diagnosis. The main differential diagnoses include invasive urothelial carcinoma and the nested variant of urothelial carcinoma; morphologic features, such as the presence or absence of background therapy-related changes and the architecture and the cytologic atypia of the nests, can help distinguish between pseudocarcinomatous hyperplasia and urothelial carcinoma.

Immunohistochemical evaluation of novel and traditional markers associated with urothelial differentiation in a spectrum of variants of urothelial carcinoma of the urinary bladder

Data on immunohistochemical expression of novel and traditional urothelial markers in the wide range of urothelial carcinoma variants have so far been very limited. In this study, whole tissue sections from 130 bladder urothelial carcinoma and variants were stained with a panel of novel and traditional immunomarkers supportive of urothelial lineage. The positivity rates were as follows: (a) urothelial carcinomas with or without divergent differentiation: GATA3 (50%), S-100P (86%), uroplakin III (20%), thrombomodulin (40%), cytokeratin 7 (CK7) (80%), CK20 (55%), p63 (87%), and high molecular weight cytokeratin (HMCK) (89%); (b) urothelial carcinoma variants (micropapillary, plasmacytoid, nested, clear cell, and microcystic): GATA3 (88%), S-100P (96%), uroplakin III (33%), thrombomodulin (49%), CK7 (95%), CK20 (61%), p63 (69%), and HMCK (96%); and (c) undifferentiated carcinomas (lymphoepithelioma-like carcinoma, small cell carcinoma, sarcomatoid carcinoma and carcinoma with rhabdoid and giant cells): GATA3 (28%), S-100P (31%), uroplakin III (0%), thrombomodulin (22%), CK7 (50%), CK20 (3%), p63 (50%), and HMCK (49%). In urothelial carcinoma with squamous differentiation, GATA3 expression was lower (20%) in contrast to p63 and S-100P. In urothelial carcinoma with glandular differentiation, GATA3 (50%) and p63 (60%) expression was lower than S-100P (100%). p63 expression was relatively lower in micropapillary (54%) and plasmacytoid (50%) variants compared with the other urothelial carcinoma variants. This study provides comprehensive data for novel and traditionally used markers to support urothelial lineage in urothelial carcinoma variants. Our findings show that GATA3, S-100P, CK7, CK20, HMCK, and p63, in the appropriate differential diagnostic setting, are useful to support urothelial lineage of variant morphologies.

Nested variant of urothelial carcinoma

Background. Nested variant of urothelial carcinoma was added to the WHO's classification in 2004. Aims. To review the literature on nested variant of urothelial carcinoma. Results. About 200 cases of the tumour have been reported so far and it has the ensuing morphological features: large numbers of small confluent irregular nests of bland-appearing, closely packed, haphazardly arranged, and poorly defined urothelial cells infiltrating the lamina propria and the muscularis propria. The tumour has a bland histomorphologic appearance, has an aggressive biological behaviour, and has at times been misdiagnosed as a benign lesion which had led to a significant delay in the establishment of the correct diagnosis and contributing to the advanced stage of the disease. Immunohistochemically, the tumour shares some characteristic features with high-risk conventional urothelial carcinomas such as high proliferation index and loss of p27 expression. However, p53, bcl-2, or EGF-r immunoreactivity is not frequently seen. The tumour must be differentiated from a number of proliferative lesions of the urothelium. Conclusions. Correct and early diagnosis of this tumour is essential to provide early curative treatment to avoid diagnosis at an advanced stage. A multicentre trial is required to identify treatment options that would improve the outcome of this tumour.

The unusual nested carcinoma of the renal pelvis

Invasive urothelial carcinoma has a potential to show divergent differentiation. Several uncommon morphological variants have been described in the recent past. One such rare type is the nested variant of urothelial carcinoma. Most of the published reports depict occurrence of this variant in the urinary bladder. We report an unusual presentation of this uncommon entity in the renal pelvis of a 54-year-old lady who presented with widespread skeletal metastases without any urinary symptoms.

Invasive low-grade papillary urothelial carcinoma: a clinicopathologic analysis of 41 cases

Typically in invasive papillary urothelial carcinoma both the overlying papillary and the invasive components are high grade. We describe a series of patients with invasive low-grade papillary urothelial carcinoma (LPUC) in which both the noninvasive and invasive components are low grade. A retrospective search from The Johns Hopkins Surgical Pathology Database and consult cases from one of the author's files from 1998 to 2011 found 54 cases of invasive LPUC, excluding the more common, unique, and already well-characterized nested variant of urothelial carcinoma. Slides were available for 41 cases and formed the basis of the current study. The mean patient age was 68.4 years, with a male predominance. The specimens consisted of 37 bladder biopsies, 1 renal pelvis biopsy, 1 cystoprostatectomy specimen, 1 nephrectomy specimen, and 1 nephroureterectomy specimen. In all cases, invasion was limited to the superficial lamina propria above the muscularis mucosae. None of the histologic features correlated with tumor recurrence. Follow-up information was available for 73% of cases, with an average time interval of 49 months. Recurrent tumor was identified in 10/29 (34%) cases; however, 34% of cases without recurrence had limited follow-up (<24 mo). Three patients showed progression in tumor grade, and 3 additional patients progressed in both grade and stage (60% stage/grade progression). Four patients developed recurrence with ureteral noninvasive LPUC (2 in the bladder and 2 in the ureter). All are alive without disease. As this lesion is being increasingly recognized, larger studies are needed to determine whether invasion arising in LPUC is a significant risk factor for future disease.

Variant (divergent) histologic differentiation in urothelial carcinoma is under-recognized in community practice: impact of mandatory central pathology review at a large referral hospital

BACKGROUND AND OBJECTIVE

Urothelial carcinoma (UC) demonstrating variant histologic differentiation is associated with poor outcomes, and certain variants exhibit differing therapeutic responses compared with pure conventional UC. Little is known about the awareness and reporting practices of UC with variant histology in community practice.

MATERIALS AND METHODS

Patients diagnosed with UC based on an outside pathologic review had their pathology centrally reviewed before instituting therapy. A discordant diagnosis was defined as the presence of variant histologic differentiation not reported by the referring institution. Variant histologic differentiation was quantitated as focal (10%-50%) or extensive (>50%).

RESULTS

Of 589 transurethral biopsies (TURBTs), 115 (19.5%) UCs demonstrated variant histologic differentiation. Muscle invasion at TURBT and extravesical disease at cystectomy was present in 69% and 52%, respectively. Of 56 patients with at least 1 year follow-up, recurrence-free survival was 56%. The majority (90%) showed a single variant histology, which was extensive in 58% of cases. Squamous differentiation (32%) was the most common variant histology identified, followed by small cell (16%), glandular (13%), micropapillary (12%), nested (8%), sarcomatoid (6%), lymphoepithelial (3%), and plasmacytoid (1%) type. Variant histologic differentiation was not documented by the referring institution in 44% of cases, of which 47% were extensive. Commonly under-recognized patterns included lymphoepithelial (2) and plasmacytoid (1) types (100%), nested (7, 87%), micropapillary (10, 83%), and small cell (7, 44%).

CONCLUSIONS

This study emphasizes the importance of central pathology review in the management of bladder cancer patients and the need for increased awareness of this relatively common phenomenon in UC.

Metastases from nested variant urothelial carcinoma of the urinary bladder in pancreatic allograft mimicking graft rejection

While not an uncommon tumor, urothelial carcinoma of the urinary bladder is rare in bladders draining pancreatic allografts. A case of urothelial carcinoma directly involving a pancreatic allograft with metastasis that occurred in a 49-year-old pancreas and kidney transplant recipient is described. Her initial clinical presentation and findings of CT scan of the abdomen suggested pancreatitis with features worrisome for rejection. A biopsy of her pancreatic allograft contained poorly differentiated carcinoma and cystoscopic biopsy disclosed an invasive high grade urothelial carcinoma arising in the background of extensive urothelial carcinoma in situ. Exploratory laparotomy revealed that the tumor invaded the right ovary and fallopian tube, cecum, and allograft with extensive retroperitoneal involvement. She underwent en bloc resection of distal ileum and cecum, resection of transplant pancreas, partial cystectomy, ileocolostomy anastomosis, and right salpingo-oophorectomy. Postoperatively, the patient was treated with four cycles of carboplatin and gemcitabine. She ultimately succumbed to her disease approximately 1 year after diagnosis. This case should alert physicians and radiologists to be aware of atypical presentation of urothelial carcinoma in bladder-drained pancreas grafts, the aggressiveness of such lesions, and the need for early biopsy to avoid diagnostic confusion with rejection.

Treatment of uncommon malignant tumours of the bladder

PURPOSE OF REVIEW

Urothelial carcinoma is the most common histological type of bladder tumours. Nevertheless, its variants and less common types represent 20% of all bladder cancers. The objective was to update the recent publications on these rare diseases and to draw conclusions for clinical management.

RECENT FINDINGS

Recent retrospective studies have been published. They refine the description of histological patterns and of immunochemistry diagnosis. Taking into account the heterogeneity of these pathologies, several groups have benefited of increased knowledge such as sarcomas and lymphomas. The need of international collaboration to study prospectively some subgroups of tumours is crucial.

SUMMARY

Rare bladder cancers have generally poor outcome and in a majority of the cases surgery, namely cystectomy remains the most important curative treatment. Specific subgroups, as lymphoma, sarcoma and dedifferentiated epithelial tumours may benefit of molecular characterization and trials with targeted drugs.

Nested variant of urothelial carcinoma of the urinary bladder

The nested variant of urothelial carcinoma (NVUC) is characterized by the presence of benign-appearing urothelial carcinoma cells in the lamina propria, sparing the surface urothelial involvement. NVUC shows aggressive clinical course despite of benign-looking histology. Herein reported are two cases of NVUC. One is 80-year-old woman, and another is 78-year-old man. In both cases, atypical cells forming nests and tubules were seen in the lamina propria without surface urothelial involvement. One case resembled nephrogenic metaplasia and another proliferated Brunn's nest or inverted papilloma. Immunohistochemically, both cases showed positive p53 and high Ki67 labeling, suggesting that both cases are malignant. Immunohistochemically, one case was characterized by positive cytokeratins, EMA, p53, Ki-67 (labeling=15%), α-methylacyl CoA racemase, CA19-9, and MUC1, and another case by positive cytokeratins, EMA, p63, p53, Ki-67 (lebeling=30%), CD10, CEA, and MUC1. Cyto keratin immunoprofiles were described and other antigens' expressions were shown. The patients are now free of tumor 6 and 15 months after the resection of the bladder tumor.

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.

Immunohistochemical diagnosis of renal neoplasms

CONTEXT

Histologic diagnosis of renal neoplasm is usually straightforward by routine light microscopy. However, immunomarkers may be essential in several contexts, including differentiating renal from nonrenal neoplasms, subtyping of renal cell carcinoma (RCC), and diagnosing rare types of renal neoplasms or metastatic RCC in small biopsy specimens.

OBJECTIVE

To provide a comprehensive review of the diagnostic utility of immunomarkers for renal neoplasms.

DESIGN

This review is based on published literature and personal experience.

CONCLUSIONS

The following markers may have diagnostic utility in various diagnostic contexts: cytokeratins, vimentin, α-methylacyl coenzyme A racemase, carbonic anhydrase IX, PAX2, PAX8, RCC marker, CD10, E-cadherin, kidney-specific cadherin, parvalbumin, claudin-7, claudin-8, S100A1, CD82, CD117, TFE3, thrombomodulin, uroplakin III, p63, and S100P. Cytokeratins are uniformly expressed by RCC, albeit in a somewhat limited amount in some subtypes, requiring broad-spectrum anti-CK antibodies, including both low- and high-molecular-weight cytokeratins. PAX2 and PAX8 are sensitive and relatively specific markers for renal neoplasm, regardless of subtype. CD10 and RCC marker are sensitive to renal cell neoplasms derived from proximal tubules, including clear cell and papillary RCCs. Kidney-specific cadherin, parvalbumin, claudin-7, and claudin-8 are sensitive markers for renal neoplasms from distal portions of the nephron, including chromophobe RCC and oncocytoma. CK7 and α-methylacyl coenzyme A racemase are sensitive markers for papillary RCC; TFE3 expression is essential in confirming the diagnosis of Xp11 translocation RCC. The potentially difficult differential diagnosis between chromophobe RCC and oncocytoma may be facilitated by S100A1 and CD82. Thrombomodulin, uroplakin III, p63, and S100P are useful markers for urothelial carcinoma. Together with high-molecular-weight cytokeratins, PAX2, and PAX8, they can help differentiate renal pelvic urothelial carcinoma from collecting duct RCC. A sensitive marker for sarcomatoid RCC is still not available. Immunomarkers are most often used for diagnosing metastatic RCC. Compared with primary RCC, expression of the above-mentioned markers is often less frequent and less diffuse in the metastatic setting. Recognizing the variable sensitivity and specificity of these markers, it is important to include at least CD10, RCC marker, PAX2, and PAX8 in the diagnostic panel.

Nephrogenic adenoma: report of a case and review of morphologic mimics

Nephrogenic adenoma, also referred to as nephrogenic metaplasia, is an uncommon benign lesion of the urothelial tract, characterized by a circumscribed proliferation of tubules, cysts, and papillae lined by cells with low cuboidal to columnar epithelium. The diagnostic features that are useful in the recognition of this benign entity are the characteristic mixture of various architectural patterns, associated stromal edema and inflammation, hyaline sheath around tubules, eosinophilic colloidlike secretion within tubules, and lack of mitotic activity. Nephrogenic adenoma can be a significant diagnostic pitfall as certain histologic features, such as the presence of enlarged nuclei with prominent nucleoli, degenerative nuclear atypia, tiny tubules with blue mucin simulating signet ring cells, and focal invasion into superficial muscle, when taken out of context, can mimic malignancy. Herein, I report a case of nephrogenic adenoma with some worrisome histologic features and review the diagnostic criteria as well as pertinent morphologic malignant mimics of nephrogenic adenoma.