Contemporary Issues in Urothelial Carcinoma of Upper Urinary Tract.

Upper urinary tract urothelial carcinoma (UTUC) is an uncommon malignancy involving the renal pelvis and ureter. Careful pathologic analysis plays a critical role in the diagnosis and clinical management of UTUC. In combination with clinical and radiologic evaluation, pathologic features can be used to stratify patients into low-risk and high-risk groups. This risk stratification can help clinicians select the optimal treatment for patients with UTUC, such as kidney-sparing (conservative) treatment, radical nephroureterectomy or ureterectomy, and perioperative systemic therapy. However, due to the technical difficulty of obtaining sufficient tissue from the upper urinary tract, it is often challenging for pathologists to accurately grade the tumor and assess tumor invasion in small biopsy specimens. Although the majority of UTUCs are pure urothelial carcinoma, a considerable subset of UTUCs show histologic subtypes or divergent differentiation. Recent studies have identified genetically distinct molecular subtypes of UTUC by examining DNA, RNA, and protein expression profiles. The prognosis of pT3 UTUC, particularly renal pelvic UC, remains controversial, and several studies have proposed subclassification of pT3 UTUC. Lynch syndrome is a significant risk factor for UTUC, and screening tests may be considered in young patients and those with familial histories of the disease. Despite significant progress in recent years, several issues remain to be addressed in the pathologic diagnosis, molecular classification, and treatment of UTUC.