Cystic renal cell carcinoma: Our series

Introduction: Complex renal cystic lesions have long posed a clinical dilemma to clinicians as they represent a heterogeneous group of both benign and malignant conditions sharing similar clinical and radiological features. The Bosniak classification system based on computed tomography (CT) imaging remains the gold standard to predict the risk of malignancy in cystic renal masses. We retrospectively reviewed our series of patients who underwent surgery for renal cysts, their histopathological diagnosis, the outcome of surgery, and follow-up. Materials and Methods: We retrospectively reviewed the inpatient charts of the hospital for patients with renal cysts undergoing surgery for the same during the period January 2000-December 2017. CT images of these patients were re-reviewed. Clinical, surgical, radiological, pathological, and postoperative outcomes were analyzed. Based on the final pathology findings, the patients were stratified into a renal cell carcinoma (RCC) or a benign tumor subgroup. Results: During the 18-year study period, 31 patients with Bosniak I simple renal cysts, 23 with Bosniak 2 cysts, 1 patient with Bosniak IIF cyst, 8 with III cyst, and 11 with IV cyst underwent surgery. None of the patients with Bosniak I, II, and IIF had malignancy on histopathological examination (HPR) of the resected cyst wall. Five of the eight patients with Bosniak III and all 11 patients with Bosniak IV cysts had malignant lesions. Histopathological variety of RCC was clear cell type with Fuhrman Grade 1–2 in all the 16 patients. None of the patients have had either local or systematic recurrence of the malignancy. Five patients died during the follow-up period due to causes other than malignancy. Conclusions: Patients with unifocal cystic RCC evaluated and managed using standard imaging carry an excellent prognosis. Bosniak classification system is very effective in predicting malignancy in categories II, IIF, and IV, but low in category III, and that 37.5% of Bosniak III cysts were benign on HPR.