CT findings and diagnostic performance of upper urinary tract carcinoma in situ

Objectives: To evaluate the CT characteristics and detectability of carcinoma in situ (CIS) of the upper urinary tract. Methods; Between January 2007 and March 2020, 28 patients (mean age: 73 years, 25 male and 3 female) with 29 pure CIS lesions of the upper urinary tract (i.e., without concomitant non-CIS lesion) who underwent nephroureterectomy were identified. The most recent CT scan performed before ureteroscopy, systemic neoadjuvant chemotherapy, or nephroureterectomy was selected for analysis. Twenty-eight patients without upper tract malignancy were selected as a control group. All images were evaluated for presence of upper urinary tract CIS using confidence levels ranging from 1 to 100 by two radiologists. The confidence level of 75 was used as a cutoff threshold for calculating sensitivity and specificity. Results: The median interval between CT scan and nephroureterectomy was 96 days. The number of true-positive lesions (per-lesion sensitivity) was 41% (12/29) and 52% (15/29) by readers 1 and 2. The true-positive lesion appeared as wall thickening in 83% (10/12) by reader 1 and 80% (12/15) by reader 2, and as a mass in 17% (2/12) by reader 1 and 20% (3/15) by reader 2. All mass-forming lesions were located in the renal collecting system. The per-patient sensitivity and specificity were 42% and 100% in reader 1, and 54% and 96% in reader 2. Conclusions: The common abnormal finding of pure CIS in the upper urinary tract was wall thickening. Pure CIS could also appear as a mass-forming lesion when it is located in the renal collecting system.

Automated summary

This study evaluated the CT characteristics and detectability of carcinoma in situ (CIS) of the upper urinary tract. The common abnormal finding of pure CIS was wall thickening, and a minority of cases presented as mass-forming lesions, mostly located in the renal collecting system.