LAUSR

Rationale Collecting duct carcinoma (CDC) is a rare neoplasm arising from the collecting duct and should be distinguished from other renal cell carcinomas that mostly originated from the proximal tubular epithelium and tumors originated from the urothelium. It usually occurs in unilateral kidney, sometimes found with cystic change. Patient concerns We present the case of a 53-year-old male suffering from repeated bilateral flank pain for 6 months, increased pain with dysuria for 5 days. Diagnosis Ultrasound showed 2 similar hybrid echo masses in bilateral kidneys with enlarged lymph nodes surrounded, which accords with magnetic resonance imaging (MRI), and intraoperative biopsy reported malignancy. Interventions An exploratory operation was performed and the mass on the left kidney was removed, but pathological result reported collecting duct carcinoma according to the morphological features and immunohistochemical tests. Also postsurgery positron emission tomography-computed tomography (PET-CT) confirmed the mass on the left kidney is also a lesion of CDC. Outcomes The patient refused chemotherapy and had an overall survival of 7 months. Lessons We presented a case of CDC involving bilateral kidneys with cystic change; this is the first case of bilateral renal occurrence with cystic change to our knowledge. Because of CDC's rapid growth and the lack of effective adjuvant treatment after surgery, the prognosis is poor and the diagnosis should be made carefully.