Background and purpose: Collecting duct carcinomas of the kidney are a rare malignant tumor accounting for 1% of renal malignancies. It is associated with aggressive nature and more than 50% of patients have metastatic disease at the time of initial diagnosis. The diagnosis of collecting duct carcinoma is often difficult and to some extent is one of exclusion. This study aimed to study the clinicopathologic features of collecting duct carcinoma of the kidney. Methods: We retrieved the data of five cases of collecting duct carcinomas of the kidney from pathology files

and determined the expressions of CK19

CAM5.2

CK7

Vimentin

CD10

P63 and PaX-8 by pathohistological observation and immunohistochemical examination. Results: The most common symptoms were blood urine

bellyache and abdomen mass. The tumor originated from the medulla of the kidney central zone. Histologically

the tumors demonstrated irregular tubular or papillary architecture with the stroma of inflammatory cells and fibrous tissue proliferation. Immunohistochemically

the tumor cells were positive for CK19(5/5)

CAM5.2(5/5)

PaX-8(5/5)

Vimentin(2/5)

CK7(1/5)

and negative for P63

CD10. Conclusion: The correct diagnosis in collecting duct carcinomas of the kidney is based on characteristic morphological features and immunophenotype labeling.