Different subtypes of carcinoma in situ of the bladder do not have a different prognosis.

Urothelial carcinoma in situ (CIS) is a high-grade lesion with different subtypes (large cell pleomorphic (LCP), large cell nonpleomorphic (LC), small cell and clinging (CL)). We explored the frequency of different subtypes in primary CIS and compared different patterns with outcome. We explored whether subtyping of CIS leads to a change in therapy and/or follow-up and should be formally reported. We included 39 patients with a primary CIS and divided them into two groups: one with LPC/LG and one with CL elements. Other subtypes did not exist or occurred only as a mixture. Patient age ranged from 36 to 80 years (mean, 63 years). Twenty had a primary CIS with one single subtype. LCP was predominant with 16 (41 %) cases; the second most important subtype was the CL with four (10 %) cases. Mean follow-up was 26.4 months, (range, 4-100 months). Thirteen patients developed a ≥ pT2 carcinoma. When progression of the different subtypes was examined, no statistical significance was found between mixed forms (p = 0.9437) nor between pure forms (p = 0.744 and p = 0.5955, respectively). Pathologists need not include different subtypes of primary CIS in their report as there is no difference in patient outcomes. It is important to recognize all different subtypes as CIS for best patient treatment.