Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 49 7 2011 07 15 483 486 EN Mohammad-Ghasem Mohseni Department of Urology, Tehran University of Medical Sciences, Tehran, Iran. Morteza Hamidi Department of Urology, Tehran University of Medical Sciences, Tehran, Iran. Alborz Salavati Department of Urology, Tehran University of Medical Sciences, Tehran, Iran. Nazir Rangzan Department of Urology, Tehran University of Medical Sciences, Tehran, Iran. Farid Kowsari Department of Pathology, Tehran University of Medical Sciences, Tehran, Iran. 2015 09 28 Benign renal cystic adenoma with out malignant features is a very rare entity. A 75 year old male with obstructive Lower tract symptoms and vague flank pain was admitted and planned for nephrectomy of non functional kidney -due to long term nephrolithiasis- intra operative finding was a cystic hydronephrotic kidney filled by thick mucous secretions which turned out to be a cyst adenoma of kidney with no malignant features. https://acta.tums.ac.ir/index.php/acta/article/view/3781 https://acta.tums.ac.ir/index.php/acta/article/download/3781/3756