Case Report IgG4-Related Kidney Disease: Report of a Case Presenting as a Renal Mass Daniele Bianchi, 1 Luca Topazio, 1 Gabriele Gaziev, 1 Valerio Iacovelli, 1 Pierluigi Bove, 1 Alessandro Mauriello, 2 and Enrico Finazzi Agrò 1 1 Department of Urology, Policlinico Tor Vergata, Rome, Italy 2 Anatomic Pathology, Department of Experimental Medicine and Surgery, Tor Vergata University, Rome, Italy Correspondence should be addressed to Daniele Bianchi; danielebianchimail@yahoo.it Received 16 April 2017; Revised 2 July 2017; Accepted 20 July 2017; Published 22 August 2017 Academic Editor: Marcus L. Quek Copyright © 2017 Daniele Bianchi et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. IgG4-related disease (IgG4-RD) is a nosological entity defned as a chronic immune-mediated fbro-infammatory condition characterized by a tendency to form tumefactive, tissue-destructive lesions or by organ failure. Urologic involvement in IgG4-RD has been described in some short series of patients and in isolated case reports, most ofen involving the kidneys in so-called IgG4- related kidney disease (IgG4-RKD). Te disease can occasionally mimic malignancies and is at risk of being misdiagnosed due to its rarity. We report the case of a 56-year-old man presenting with a right renal mass suspected of being malignant. Laboratory tests showed normal creatinine levels, a high erythrocyte sedimentation rate, and high levels of C-reactive protein and microalbuminuria. Te patient underwent radical right nephroureterectomy and histopathologic examination revealed features proving IgG4-RKD. He was therefore referred to immunologists. Typical clinical presentation of IgG4-RKD includes altered renal function with inconstant or no radiologic fndings. Conversely, in the case we presented, a single nodule was detected upon imaging evaluation, thus mimicking malignancy. Tis raises the issue of a proper diferential diagnosis. A multidisciplinary approach can be useful, although in clinical practice the selection of patients suspected of having IgG4-RKD is critical in the cases presenting with a renal mass that mimics malignancy. 1. Introduction IgG4-related disease (IgG4-RD) is a recent nosological entity defned as a chronic immune-mediated fbro-infammatory condition [1] characterized by tumefactive, tissue-destructive lesions or by organ failure [2]. IgG4-RD potentially involves nearly every anatomic site [3, 4], occasionally including urologic structures, as described in some short series of patients and in isolated case reports [5]. Typical histopatho- logic features are lymphoplasmacytic infltrate rich in IgG4 plasma cells, obliterative phlebitis, and storiform fbrosis, while laboratory tests may reveal an inconstantly elevated serum IgG4 concentration [6]. IgG4-related kidney disease (IgG4-RKD) is the most common among urologic manifestations of IgG4-RD, usu- ally presenting in the form of tubulointerstitial nephritis (TIN) [7–9], although some cases of membranous glomeru- lonephritis (MGN) have been described [9–11]. IgG4-RKD presenting as a solid renal mass has rarely been described [5], and conventional imaging—including ultrasound scans, computed tomography (CT), and magnetic resonance imag- ing (MRI)—has proven to be of limited usefulness in deter- mining IgG4-RD [12]. 2. Case Report We report the case of a 56-year-old Caucasian man presenting with a right renal mass (12 × 9 × 8 cm) revealed by CT (Fig- ure 1) and MRI (Figure 2). Te mass was localized at the upper pole of the right kidney, extending to the renal fascia towards the caval vein and iliac vessels and involving the vascular Hindawi Case Reports in Surgery Volume 2017, Article ID 9690218, 6 pages https://doi.org/10.1155/2017/9690218