AwardsStudent Travel Stipend Award
To determine the percentage of small (<3cm) complex cystic renal lesions that regress based on follow-up studies and to investigate predictive clinical factors.
METHOD AND MATERIALSA hospital database was searched from 1/1/10, to 9/2/15, for Bosniak category (BC) 2F, 3 and 4 cysts studied with C+ CT or MRI and with follow up. Two readers independently assigned a BC to the initial and last studies. Demographics and clinical outcome of patients with lesions that regressed from BC 2f, 3 or 4 (or remained stable as BC 2f), were compared with those that progressed. The relationship of progression with age, sex and history of renal cell carcinoma (RCC) was assessed using Fisher’s exact test. A subgroup analysis was performed on patients with lesions that were assigned a BC of 2f by both readers. Inter-observer agreement was assessed using Kappa statistics.
RESULTS106 patients (71:35 M:F, avg. age 61) were identified with a dominant complex cystic renal lesion. 81 of 106 lesions (76.4%) regressed from BC 2f, 3 or 4 (60), or remained stable as a 2f lesion (21) (Kappa = 0.57). Two regressed lesions were resected; one of these regressed from BC 4 to 2f, was resected and was a low grade papillary RCC (this was in a 52 year old female with a history of RCC); the other was benign (renal dysplasia) in a patient without a history of RCC. 8 of the 25 progressed or stable BC 3 or 4 lesions were resected, of which 7 were RCC (87.5%) and 1 benign (cystic nephroma). To date, no patients recurred or had metastatic disease. Progression was associated with a history of RCC (P = .04).Kappa between the 2 readers for assigning a BC 2f was 0.41. 50 lesions (47.1%) were assigned a BC 2f by both readers. Kappa between the 2 readers for progression of these lesions was 0.43. 6 lesions (12%) progressed on follow up imaging. 3 of these were resected and were malignant. All 3 of these occurred in patients with a history of RCC. Progression was associated with history of RCC (p=0.007).
CONCLUSIONBased on this study, 76.4% of small (<3cm) BC 2f, 3 and 4 cystic renal lesions regress. Therefore, small size should be a consideration for conservative management. In the absence of a history of RCC these lesions may be amenable to imaging follow up rather than resection.
CLINICAL RELEVANCE/APPLICATIONIn the absence of a history of RCC, small BC 2F, 3 and 4 lesions may be amenable to imaging follow up rather than immediate resection.