Collecting duct carcinoma of kidney: Differential diagnosis of neoplasms involving the renal medulla

Collecting duct carcinoma is a rare renal neoplasm that originates from the distal segment of the collecting duct in the renal medulla pyramids. Of all renal epithelial neoplasms, collecting duct carcinoma is the most aggressive, showing early metastatic behavior, poor prognosis, and limited response to immunotherapy. Recently, chemotherapy regimens commonly used for urothelial carcinoma have been demonstrated to be superior to the ones used for renal cell carcinoma in patients affected by this malignancy. Therefore, distinction between collecting duct carcinoma and other renal neoplasms involving renal medulla is desirable.