Liang Cheng

Precise Microdissection of Human Bladder Carcinomas Reveals Divergent Tumor Subclones in the Same Tumor

Human bladder carcinoma is thought to arise from a field change that affects the entire urothelium. Whether independently transformed urothelial cell populations exist in the same patient is uncertain.

Renal Pelvis and Ureter

The renal pelvis and ureter are conduits composed of interlacing bundles of spirally oriented smooth muscle, lined by urothelium. Their function depends upon the presence of intrinsically normal musculature and proper spatial orientation relative to the bladder. Surgical correction of malformations may involve excision of an intrinsically defective segment of the collecting system (as in ureteral diverticulum, congenital ureteropelvic junction obstruction, ureterocele, and primary megaureter), or the reconstitution of proper anatomy (as in correction of ureteral reflux, ureteral ectopia, or paraureteral diverticulum). The status of the musculature of an excised segment of the drainage system is of prime importance; the overlying mucosa is generally normal.

Testis and Paratesticular Structures

Chapter 4 presents main clinical and pathologic characteristics of tumors and tumor-like conditions of the testes and para-testicular structures. Emphasis is placed on rare and recently described entities. Diagnostic pathologic and immunohistochemical features useful in differential diagnosis are key characteristics described in text and tables. Representative images illustrate both common and rare tumors and tumor-like conditions of the testes and para-testicular structures.

Tumors of the Urinary Bladder

Nearly half of all bladder tumors are noninvasive (stage pTa) papillary neoplasms of urothelial origin. These tumors have been intensively investigated for many decades, and a number of concepts regarding their biologic behavior and prognosis have been well established. Prognosis for these tumors is influenced by tumor size, tumor multifocality, recurrence status, coexistence of carcinoma in situ, and histologic tumor grade [1–6]. The first four elements are straightforward. However, there has been a long-standing lack of agreement among pathologists concerning the ideal system for grading these tumors. A uniform grading system for bladder cancer will allow for valid comparison of treatment results among different centers. The 1973 WHO classification is preferred by some authors because it allows comparison of results between different clinical centers. It is a robust, time-tested, and reasonably reproducible method for pathologic reporting of bladder tumors. The 1998 WHO/ISUP classification of bladder tumors, and its adoption in the 2004 WHO classification, has been the subject of considerable controversy [3, 7–28]. In particular, there is poor interobserver agreement in the diagnostic categories of papillary urothelial neoplasm of low malignant potential (PUNLMP) and low-grade urothelial carcinoma, two new categories in the 2004 WHO system [8, 9, 12, 29–34]. Use of both the 1973 and 2004 WHO classifications (former 1998 ISUP/WHO) has been recommended by some [3, 8, 11, 12, 35–37]. We recently introduced a new four-tiered grading system, which expands previous grading systems to include an additional category of noninvasive papillary carcinomas with exceptionally abnormal cytologic characteristics (Fig. 8.1, Table 8.1) [38]. This new grading system has the combined strengths of both 1973 WHO and 2004 WHO grading system [38].

Tumors of the Kidney

Ever since the first renal neoplasm was reported nearly 200 years ago, it has become evident that a very large number of neoplasms of diverse types can arise within the kidney. Especially in the past 50 years, classification systems for renal neoplasms have become increasingly sophisticated as distinctive morphologic patterns in renal neoplasms have been recognized and correlated with clinical findings. Ancillary diagnostic tools, including electron microscopy, immunohistochemistry, cytogenetics, and molecular diagnostic techniques have made it possible to detect distinctions between various types of renal neoplasms. Taking into consideration the contributions of numerous investigators over many decades, the most recent World Health Organization classification of renal neoplasms encompassed nearly 50 distinctive renal neoplasms, and it is inevitable that the next version of this classification will include several newly recognized renal neoplasms. In this chapter, we examine a number of these entities, particularly those most often encountered clinically and submitted for pathologic evaluation.