|Year : 2017 | Volume
| Issue : 6 | Page : 947-950
Utility of the laminin immunohistochemical stain in distinguishing invasive from noninvasive urothelial carcinoma
Dinesh Pradhan, Milon Amin, Shveta Hooda, Rajiv Dhir, Sheldon Bastacky, Anil V Parwani
Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
|Date of Web Publication||13-Dec-2017|
Dr. Dinesh Pradhan
Department of Pathology, University of Pittsburgh Medical Center, 200 Lothrop Street, Pittsburgh, PA 15213
Source of Support: None, Conflict of Interest: None
Background: To study the utility of the laminin immunostain in distinguishing invasive from noninvasive urothelial carcinoma (UC). The distinction is difficult but clinically significant as it can affect the decision to administer intravesical Bacillus Calmette–Guerin or can even lead to cystectomy.
Materials and Methods: Representative sections of the transurethral resection of bladder tumor specimens from 25 cases of formalin-fixed paraffin-embedded invasive UCs and 25 cases of noninvasive UCs were selected for immunohistochemical (IHC) staining with laminin (Ventana, Oro Valley, AZ, USA). These cases were selected using a computer-assisted search of our laboratory information system (Cerner CoPath). Tissue from five paraffin-embedded tissue blocks containing unremarkable urothelial-lined bladder parenchyma was chosen as controls.
Results: All five control cases demonstrated crisp linear staining of the basement membrane underlying the unremarkable urothelium. Similar findings were also noted in the 25 cases of noninvasive UC. All 25 cases of the invasive UC demonstrated a complete absence of the staining around invasive and malignant urothelial cells. Laminin staining was also noted in both the muscularis mucosae and the detrusor muscle, although the pattern of staining in these areas was granular and was distinguishable from the crisp linear staining of the basement membrane.
Conclusion: Laminin IHC staining can be useful in differentiating invasive from noninvasive UC.
Keywords: Invasion, laminin, urothelial carcinoma
|How to cite this article:|
Pradhan D, Amin M, Hooda S, Dhir R, Bastacky S, Parwani AV. Utility of the laminin immunohistochemical stain in distinguishing invasive from noninvasive urothelial carcinoma. J Can Res Ther 2017;13:947-50
|How to cite this URL:|
Pradhan D, Amin M, Hooda S, Dhir R, Bastacky S, Parwani AV. Utility of the laminin immunohistochemical stain in distinguishing invasive from noninvasive urothelial carcinoma. J Can Res Ther [serial online] 2017 [cited 2018 Jun 19];13:947-50. Available from: http://www.cancerjournal.net/text.asp?2017/13/6/947/179523
| > Introduction|| |
In the realm of urologic surgical pathology, one diagnostic dilemma described by Cox and Epstein  is a deceptively simple concept of the identification of lamina propria invasion in urothelial carcinoma (UC). In particular, identification of invasion can be difficult in transurethral resection of bladder tumor (TURBT) specimens, where the specimen is fragmented, cauterized and tangentially oriented, which can mimic the appearance of an invasive tumor. Identification of invasive versus in situ UC is significant from therapeutic as well as prognostic standpoint. The decision to administer intravesical Bacillus Calmette–Guerin (BCG) or to perform cystectomy in the absence of muscularis propria (detrusor muscle) invasion if the carcinoma is refractory to medical management depends on lamina propria invasion. The diagnostic difficulty among pathologists in the identification of invasion has been frequently documented.,,
Over the past decade, the advent of immunohistochemical (IHC) studies has provided the pathologist with additional tools. Laminin was described as a component of basement membrane in 1979. Conceptually, to demonstrate lamina propria invasion, urothelial neoplasm should break through the basement membrane underlying the urothelium, and thus an absence of laminin staining would support the presence of an invasive neoplasm. Unusual cases of cystitis cystica with a “highly infiltrative appearance” and with a laminin staining around each and every angulated small nest of urothelial cells have been described. However, some studies have raised the possibility of laminin-producing abilities of urothelial neoplasms., If such abilities are confirmed, then the presence or absence of laminin staining by immunohistochemistry would theoretically be unreliable for the diagnosis of invasive versus noninvasive UC. Hence, this brief quality analysis study was aimed at evaluating the ability of the laminin antibody to discriminate between invasive and noninvasive UC.
| > Materials and Methods|| |
Using a computer-assisted search of our laboratory information system (Cerner CoPath), formalin-fixed paraffin-embedded (FFPE) tissue blocks were chosen from TURBT specimens of 25 different patients with invasive UC and 25 cases of noninvasive papillary UC, including both high and low grade. Invasive carcinoma was confirmed in cystectomy specimens from all 25 cases. Attempts were made to locate cases of florid cystitis cystica for comparison, but tissue blocks from these particular cases were not available for review. Hence, tissues from five additional FFPE tissue blocks with unremarkable urothelial-lined bladder parenchyma were chosen as controls. Specimens were processed for histological examination using conventional methods. Histologic sections were stained with hematoxylin and eosin (H and E). IHC studies (Laminin, Ventana, Oro Valley, AZ, USA) were also performed using FFPE sections. Avidin-biotin-peroxidase complex and peroxidase-antiperoxidase techniques were employed with appropriate positive and negative controls.
| > Results|| |
All five control cases demonstrated crisp linear staining of the basement membrane underlying the unremarkable urothelium. Such findings were also noted in all the noninvasive papillary UC [Figure 1] and [Table 1]. All 25 cases of invasive UC demonstrated a complete absence of staining around invasive and malignant urothelial cells [Figure 2]. Laminin staining was also noted in both muscularis mucosae and detrusor muscle, although the pattern of staining in these areas was granular and was distinguishable from the crisp linear staining of the basement membrane [Figure 2]. In one case, a rare focus of carcinoma showed a rim of laminin staining; however, comparison with the H and E-stained slide showed this focus to represent an area of angiolymphatic invasion. No technical issues or failed immunostains were encountered in this series.
|Figure 1: Staining characteristics of laminin in noninvasive urothelial carcinoma: Crisp linear stain representing basement membrane is noted around each group of urothelial cells, regardless of the presence of tangential orientation or sectioning. The staining of the adjacent blood vessels is noted in the lower center of the image (immunoperoxidase stain for laminin, ×200)|
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|Figure 2: Staining characteristics of laminin in invasive urothelial carcinoma. (a and b) Absence of laminin staining in an area of invasive urothelial carcinoma (immunoperoxidase stain for laminin, ×40, ×200); (c) while laminin highlights the detrusor muscle, no staining is seen around the nests of malignant cells of an invasive urothelial carcinoma with micropapillary features (immunoperoxidase stain for laminin, ×100); (d) laminin highlights several blood vessels in an invasive urothelial carcinoma, but there is no staining around the aggregates of invasive urothelial cells (immunoperoxidase stain for laminin, ×40)|
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| > Discussion|| |
Laminins, a major subset of proteins in the basal lamina provides a protein network foundation for the epithelial surfaces of most organs. They are an essential class of proteins, as they affect cell differentiation, migration, adhesion, and even cell survival.
More specifically, laminins are trimeric proteins that contain alpha, beta, and gamma chains. Laminin molecules are named on the basis of their chain composition. For example, laminin-513 contains alpha-5, beta-1, and gamma-3 chains. As many as 14 other chain combinations have been identified. Intersection of these trimeric proteins forms a lattice capable of binding extracellular matrix molecules of neighboring cells. If laminins are defective, they can cause a number of musculoskeletal imbalances, including but not limited to muscular dystrophy, skin blistering diseases, and even nephrotic syndrome. In addition, laminins can be broken down by malignant cells, allowing them to invade into the lamina propria and beyond.
In this series, the absence of laminin staining in all 25 cases of invasive UC is reassuring and may suggest a high degree of usefulness in differentiating invasive from noninvasive UC. However, several limitations must be raised with this study. First, additional cases need to be analyzed in order to provide statistical significance. Cases with challenging features, including more extensive cautery artifact, needs further evaluation to demonstrate the performance of laminin staining in challenging scenarios. Moreover, cases must include patients with proven florid cystitis cystica, and to validate the presence of cystitis cystica, they should have a fair clinical follow-up period showing no evidence of UC. Comparison of laminin to other basement membrane antibodies, such as those to collagen IV, may also be helpful.
Of particular interest is the staining pattern of laminin in cases of angiolymphatic invasion. In theory, the staining pattern of a widely angioinvasive UC could mimic that of florid cystitis cystica. However, correlation with the morphologic findings, in addition to IHC analysis for angiolymphatic markers (i.e., CD34, CD31 and D2–40) can help resolve such cases. Some institutions have implemented the use of a dual pankeratin-laminin immunostain to more clearly locate areas of invasive UC, although the degree of staining with the red chromogen in dual immunostains may be weaker in comparison to two immunostains being performed on two different tissue sections.
Besides being very helpful in distinguishing invasive from noninvasive UC, laminin immunostaining has also been shown to have therapeutic and prognostic implication.,,,,,, It has also been shown in various studies to be more helpful in confirming microinvasion in difficult cases.
The distinction of invasive from noninvasive UC is very important for management and prognostication. About 70–75% of the UC present as nonmuscle invasive tumors of which majority (70–75%) are confined to the bladder mucosa (Stage Ta) and have a very low risk of progression, mostly the low-grade tumors. These Ta tumors are mostly managed with TURBT and follow-up. On the other hand, tumors that invade beyond the basement membrane into the sub-epithelial connective tissue (i.e. lamina propria) are Stage T1 tumors and represent approximately 25% of all nonmuscle invasive tumors. T1 UC has a worse prognosis than Ta tumors with a greater risk of progression to muscle-invasive disease and hence in addition to TURBT they require intravesical BCG and/or mitomycin C in the majority of the cases. However, these days more extensive individualized risk stratification of the tumor guides management. Thus, laminin staining can help in risk stratification and in the better guidance of therapeutic options.
| > Conclusion|| |
In this series, we demonstrate that the laminin IHC staining can be useful in differentiating invasive from noninvasive UC. The immunostaining can be particularly helpful in confirming microinvasion in the diagnostically challenging cases of microinvasive UC. No case of invasive UC in this series showed any immunoreactivity or background staining with laminin. However, several limitations of this study are noted, and analysis with more cases is needed to provide more substantiative evidence for this claim.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]