Radiographic surveillance of minimally and moderately complex renal cysts.

OBJECTIVE To assess the effectiveness of radiographic surveillance for managing minimally and moderately complex renal cysts. PATIENTS AND METHODS Forty-three patients with 50 minimally or moderately complex renal cysts underwent radiographic surveillance at our institution. Study inclusion criteria were surveillance for >2 years (36 patients, mean follow-up 3.0 years) or surveillance for >6 months with subsequent surgical excision (seven patients, mean follow-up 3.3 years). RESULTS The complexity of the renal cysts was in the form of high attenuation before contrast-enhanced imaging ('hyperdense') in 29 patients, thin septations in nine, borderline enhancement in six, thin calcifications in five, and a thick wall in one. The mean initial largest dimension was 2.9 cm and the mean final dimension was 3.0 cm, with the size increased in 29 cysts, decreased in 14 and with no change in seven. The cyst character worsened in seven patients, improved in four and did not change in 39. Eventually seven patients had surgery (laparoscopic partial nephrectomy in five and laparoscopic radical nephrectomy in two), which revealed renal cancer in five. Surgical intervention was prompted by growth alone in two patients, growth and worsening of cyst characteristics in two, new onset of flank pain in one, and appearance of an enhancing nodule in the wall or septa in two. CONCLUSION Radiographic surveillance is an effective method for managing patients with minimally or moderately complex renal cysts. Malignant lesions can be identified and removed while still of low grade and contained, and surgery can be avoided in most patients.