Accessed November 14th, This classification WHO is applicable to tumors that occur throughout the urothelial tract including the bladder, ureter, renal pelvis and urethra Urothelial carcinoma UC is the most common malignant neoplasm of the urothelial tract High propensity for divergent differentiation and variant morphologies.
Images hosted on other servers: Infiltrating urothelial carcinoma. Histological variations and provisional entities of urothelial carcinoma NOT included in the current WHO classification. Additional references. Board review style question 1. Which of the following tumors demonstrate invasion tumor beyond the basement membrane? Infiltrating urothelial carcinoma Inverted urothelial papilloma Papillary urothelial neoplasm of low malignant potential Urothelial carcinoma in situ Urothelial papilloma.
Board review style answer 1. Sign up for our Email Newsletters. There are only two grades of carcinoma, low grade and high grade. This dichotomy is equally advantageous for the management of these tumors by oncologists.
The label of carcinoma is not used for a category of very low grade urothelial neoplasms with particularly excellent long-term prognosis Figure 1. The morphological criteria of diagnostic categories were described in detail to improve interobserver reproducibility [12].
However, the and WHO classifications are not directly interchangeable []. Many centers, like ours, use both the classifications simultaneously []. This exercise is meant to educate the treating physicians about the changes brought about by WHO classification in context of the original WHO classification and may be continued till such time that the urologists and oncologists completely adopt the new classification.
But, the most important question that arises here is that, has WHO classification attained the status of gold standard schema amongst the existing grading systems for histological grading of the noninvasive urothelial neoplasms?
The reasons lie in the inherent subjectivity and interobserver variability of all histopathological assessments. All the existing classifications of grading urothelial neoplasms including WHO classification were developed based on expert opinion and without clinical evidence base and prior validation [2].
Although not related to urologic pathology, the Oxford classification of IgA nephropathy has recently been developed based on true international consensus process and with prior testing of reproducibility and clinical evidence base [21].
This classification can serve as a role model for adopting a similar approach for developing a truly consensus based and reproducible classification in other areas of pathology [22]. Moreover, the major focus of all existing classifications has been on morphological criteria only. Perhaps, it is high time that we focus our research to the discovery and use of immunohistochemical IHC , molecular genetic and omics markers to further refine and fine tune the classification.
These markers will also facilitate an objective evaluation of the biological potential of urothelial neoplasms. A few studies have found that a small battery of IHC markers can successfully meet this need. Further, large scale and multicenter studies using novel markers are needed to validate these findings [23]. For now, it is helpful to use both the and WHO classifications simultaneously in order to facilitate the appropriate management of these neoplasms.
In summary, although WHO classification of noninvasive urothelial neoplasms represents a significant improvement over the previous classifications, it has not yet achieved the coveted gold standard status among the existing classifications. Its use has not been uniform through out the world and many centers still use both and classifications.
There are no conflicts of interest with regard to the present study. Histologic grading of urothelial carcinoma: a reappraisal. Hum Pathol ; 43 : Histologic grading of noninvasive papillary urothelial neoplasms. Eur Urol ; 51 : The WHO classification of bladder tumors: a summary and commentary.
Int J Surg Pathol ; 13 : Non-invasive urothelial neoplasms: according to the most recent WHO classification. Eur Urol ; 46 : Eur Urol ; suppl 8 : Morphological diagnosis of urothelial neoplasms. J Clin Pathol ; 61 : Morphological classification and definition of the benign, preneoplastic and non-invasive neoplastic lesions of the urinary bladder. Histopathology ; 53 : Am J Clin Pathol ; : Histologic typing of urinary bladder tumors. Geneva, Switzerland: World Health Organization; Bladder Consensus Conference Committee.
Am J Surg Pathol ; 22 : Non-invasive urothelial tumours. Cancer ; 96 : Papillary urothelial neoplasm of low malignant potential: reliability of diagnosis and outcome. BJU Int ; 93 : Papillary urothelial neoplasms of low malignant potential.
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