[Intraluminal renal metastasis from a rectal adenocarcinoma: an unusual site]

Primary adenocarcinoma of the urinary tract are uncommon. But secondary involvement of pyelocalyceal system by metastasis of colorectal origin is rare. We report a case of late rectal metastasis with renal pelvis growth presenting as a pyonephrosis. This study emphasizes the relevance of cytokeratin 7 and 20 immunostaining in such differential diagnosis.