The Benign Renal Masses that Were Exposed after Nephron-Sparing Surgery: “Postsurgical Fatty Tumor.” Is It Related to the Surgical Technique?

After nephron-sparing surgery (NSS), postsurgical fatty tumor could be mistakenly reported as angiomyolipoma during radiologic imaging of some patients. In the present paper, we studied the postsurgical fatty tumor detected after NSS but not covered before in the literature. In addition, we also evaluated whether the postsurgical fatty tumor was related to the surgical technique employed. Patients admitted to the urology department of our university hospital from 2014 to 2019 and operated with open NSS were evaluated retrospectively. We detected those 156 patients were operated with NSS. Nine patients with angiomyolipoma as primary pathology and four patients with surgical border positivity were excluded from the study. The patients were divided into two groups based on the repair of tumor extraction region. In Group 1, fatty tissue was used for repair, and Group 2 is the primary repair group. In all, 143 patients (Group 1 = 79, and Group 2 = 64) were included in the study. No demographic and radiologic differences, such as number of patients, age, gender, positioning of tumor, mass localization, tumor diameter, and RENAL nephrometry scoring system, were detected between the two groups. Postsurgical fatty tumors were detected in 28 patients in Group 1 and in two patients in Group 2 (P < 0.001). In patients with negative surgical margins after partial nephrectomy, lesions that were radiologically detected mimicking as angiomyolipoma were defined as “postsurgical fatty tumor.” This mass containing adipose tissue only neither depicted vascularization and enhancement nor increase in size for at least 1 year. We assumed that these lesions must be followed as benign lesions not requiring additional treatment.