A case of immunoglobulin G4-related inflammatory pseudotumor mimicking renal cell carcinoma

  • Hiroshi Watanabe
  • Hajime Tanaka
  • Yasuhisa Fujii
  • Makoto Kodama
  • Takumi Akashi
  • Tomoyuki Fujioka
  • Kazunori Kubota
  • Yukihisa Saida
  • Ukihide Tateishi
Special Section: Distinguished Papers from JSAR


In a 69-year-old woman with a history of Mikulicz’s disease, a hypoechoic solitary renal mass was identified on routine ultrasound examination. Based on the findings of computed tomography (CT) and magnetic resonance imaging (MRI), renal cell carcinoma was a possible diagnosis. Subsequent partial nephrectomy revealed a mass characterized by an increased number of blood vessels, internal hemorrhage, and a thick fibrous capsule. Immunohistochemically, the mass comprised of tubulointerstitial nephritis with increased immunoglobulin (Ig)G4-positive plasma cells and fibrosis. Generally, diagnosis of IgG4-related kidney disease (IgG4-RKD) is not difficult when the kidney is involved together with other systemic involvements. However, diagnosis becomes harder when a solitary renal mass appears as a single-organ involvement. On precise review of our imaging findings, MRI signals were markedly affected by hemorrhage, so the mass showed hypointensity on both T1- and T2-weighted imaging, and the signal of in-phase images decreased. Dynamic MRI showed no apparent enhancement of the mass, while CT showed an apparent enhancement effect. Capsule formation was another key finding for IgG4-RKD and was recognized as a gradually enhancing boundary zone surrounding the mass on both CT and MRI. When a solitary renal mass is associated with hemorrhage and thick capsule formation, inflammatory pseudotumor should be considered as differential diagnosis.


IgG4-related disease IgG4-RKD Pseudotumor Renal cell carcinoma 



This study received no specific grant from any funding agency.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from the patient in the study.


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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Diagnostic RadiologyTokyo Medical and Dental UniversityTokyoJapan
  2. 2.Department of UrologyTokyo Medical and Dental UniversityTokyoJapan
  3. 3.Department of Comprehensive PathologyTokyo Medical and Dental UniversityTokyoJapan

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