[Clear cell adenocarcinoma of the urinary tract: a clinicopathological analysis of nine cases].

Objective

To study the clinicopathological features and key differential diagnosis of clear cell adenocarcinoma (CCA) of the urinary tract.

Methods

A retrospective analysis was performed on the clinicopathological data, immunophenotypes, and molecular test results of patients with pathologically confirmed primary CCA of the urinary tract at Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China from December 2015 to September 2024. This study was supplemented by a review of the relevant literature.

Results

Nine patients were included (1 male and 8 females), age 57.0 (44.5, 61.0) years old. The main symptoms were urinary tract irritation and hematuria. Th lesions were in the urethra of 5 patients and in the bladder in 4 patients. Macroscopically, the tumors were cauliflower-like, with edema and firm consistency. Microscopically, they showed mostly papillary/tubular-cystic structures, with solid sheet-like arrangements. The tumor cells showed clear or eosinophilic cytoplasm, moderate to high nuclear grade, prominent nucleoli, and frequent mitotic figures. The tumor cells also exhibited strong expression of PAX8, CK7, and HNF1-β, various positivity of Napsin A and P504s, and partial expression of SOX17, CK20, and GATA3. The Ki-67 index ranged from 30% to 70%, and p53 showed a heterogeneous expression pattern. The cells were negative for p63 and the renal cell carcinoma marker (RCC). Among the 7 cases subject to urine fluorescence in situ hybridization (FISH) testing, 5 cases showed abnormal centromeric signals. One case underwent next-generation sequencing (DNA-seq) and harbored a nonsense ARID1A mutation. Two patients underwent radical surgery, 3 total urethrectomy, and 4 palliative surgery. Four patients received postoperative chemotherapy. The follow-up ranged from 9 to 58 months: 3 patients had tumor recurrence while 2 died.

Conclusions

CCA of the urinary tract is a rare and aggressive malignancy. Its histological morphology resembles that of ovarian CCA. The diagnosis should be based on a combination of morphological features and immunophenotype. It is recommended to use PAX8, CK7, HNF1-β, and Napsin A as a core immunohistochemical panel, while testing SOX17 can also help.