Incidental detection of collecting duct carcinoma from a hydronephrotic kidney- a case report of a rare tumor with unusual presentation

We present here a case of a collecting duct carcinoma in a 60 yr old male who presented with a history of pain in the right flank for 1 month. He was evaluated a hydronephrotic kidney with nephrolithiasis and significant impairment of parenchymal functioning on USG and IVP. Nephrectomy was done and was sent for histopathological study. Grossly enlarged kidney and on cut section the renal parenchyma is compressed into a thin rim of tissue measuring 0.5 cm. Corticomedullary junction was indistinct and the pelvicalyceal system is dilated and contains blood clot. No growth identified. Microscopy showed a tumor in the medulla with proliferation of tubules and papillary structure. Epithelium showed marked anisonucleosis, prominence of nucleoli, and characteristic hobnailing of cells with desmoplastic stroma. It was diagnosed as collecting duct carcinoma of right kidney.