Invasive urothelial carcinoma with molecular types

Invasive urothelial carcinoma (UC) is a highly aggressive disease characterized by rapid progression and metastasis, requiring significantly different treatment from that of noninvasive UC. Bladder UC invasion is initiated by infiltrative growth through the urothelial basement membrane into the lamina propria (LP). Invasive UC demonstrates a constellation of characteristic morphologic features, which help the recognition of minimal, superficial invasion into the LP in small transurethral biopsy specimens. Cancer invasion also induces fibrosis, inflammation, reaction artifact, and myxoid changes in the adjacent stroma. The muscularis propria (MP) is the major landmark in bladder cancer stage, which divides invasive UC into superficially and deeply invasive diseases; however, MP invasion should be differentiated from muscularis mucosae invasion because of their significant difference in cancer stage and treatment. Lymphovascular invasion is another significant prognostic factor in bladder cancer, but its diagnosis should be strictly based on a set of histologic criteria because of its therapeutic implication. Involvement of the prostate by UC may arise from the bladder or prostatic urethra, which should be staged differently according to cancer origin. Recent genomic studies of invasive bladder UC have revealed several distinct molecular subtypes, which demonstrate not only specific molecular signatures but also different clinicopathologic features. Accurate pathologic and molecular analyses of invasive bladder UC provide crucial guidance in the treatment and prognosis of this aggressive disease.