Original Study Features of Ipsilateral Renal Recurrences After Partial Nephrectomy: A Proposal of a Pathogenetic Classification Alessandro Antonelli, 1 Maria Furlan, 1 Regina Tardanico, 2 Simona Fisogni, 2 Mario Sodano, 1 Francesca Carobbio, 1 Sandra Belotti, 1 Alberto Cozzoli, 1 Tiziano Zanotelli, 1 Claudio Simeone 1 Abstract This report concerns renal cell carcinoma: we investigate features of ipsilateral relapse after nephron-sparing surgery. This topic is poorly investigated in the literature, in particular if relapse could be related to a persis- tence of the primary tumor or to a newborn one. We analyzed 18 cases of relapse after partial nephrectomy subsequently submitted to salvage nephrectomy. After revision of the anatomical specimens we found 3 types of relapse related to different etiology, histology, and mostly to different prognosis. Background: Poor data are reported on the pathogenesis of ipsilateral relapse (IR) after partial nephrectomy (PN). The objective of this study was to investigate features of IR after PN with the intention to propose a pathogenetic classification. Materials and Methods: Retrospective consultation of an institutional database that stores the data of 683 patients submitted to PN since 1993. The clinical, radiological, and follow-up data of the cases submitted to salvage nephrectomy due to an IR were analyzed. The slides of the sections from the tumor-parenchyma interface of PN and the bed of resection from the specimen of nephrectomy were reviewed. Results: Eighteen patients were submitted to salvage nephrectomy for an IR. In 12 cases the IR harbored into the site of PN and a mixture of cancer cells and granulomatous reaction was found at the resection bed (IR type A). In the remaining 6, in microscopy of the resection bed was found only fibrosis: 3 of these cases had a clear-cell renal cell carcinoma (RCC) with diffuse microvascular embolization and the relapse in the same portion of the kidney of the primary tumor (IR type B); the other 3 had a noneclear-cell RCC and the primary and relapsing tumors were located in distinct portions of the kidney (IR type C). Six patients (4 IR type A, 2 type B) had a further pro- gression and 5 of them died due to RCC. Conclusion: More frequently an IR is due to the incomplete resection of the primary tumor (IR type A), in a minority of the cases to the local spread of the tumor by microvascular embolization (IR type B), or true multifocality (IR type C). The prognosis of IR not due to multifocality (type A and B) is poor, despite salvage nephrectomy. Clinical Genitourinary Cancer, Vol. -, No. -, --- ª 2017 Elsevier Inc. All rights reserved. Keywords: Ipsilateral recurrence, Nephron-sparing surgery, Pathogenesis, Renal cell carcinoma, Salvage surgery Introduction Since a decade, partial nephrectomy (PN) has been preferred to radical nephrectomy for all cT1 renal cell carcinoma (RCC) 1 because of equivalent oncologic outcome but better renal function preservation and a lower incidence of chronic kidney disease. 2 Because of this trend, larger and more aggressive tumors are now treated in a conservative manner so that a higher incidence of oncological failures is expected. 3,4 However, the results of several large retrospective studies showed that the progression rate after partial versus radical nephrectomy is similar and depends on the features of the tumor, rather than the surgical procedure. 5,6 This evidence is easily acceptable in case of distant metastases, because micrometastasis already existing at the time of surgery are not amenable to be cured by any local treatment. Conversely, in case of a relapse in the kidney submitted to PN (IR, ipsilateral recurrence) some concerns on the primary procedure can be raised because, clearly, radical nephrectomy is not burdened by this risk. 1 Department of Urology 2 Department of Pathology, Spedali Civili Hospital, University of Brescia, Brescia, Italy Submitted: Dec 23, 2016; Revised: Apr 4, 2017; Accepted: Apr 14, 2017 Address for correspondence: Maria Furlan, MD, Spedali Civili Hospital, University of Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy E-mail contact: mariachiara.furlan@gmail.com 1558-7673/$ - see frontmatter ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.clgc.2017.04.028 Clinical Genitourinary Cancer Month 2017 - 1