title: Inflammatory pseudotumors of the kidney and the lung presenting as immunoglobulin G4-related disease: a case report.
abstract: BACKGROUND
  It has been reported that immunoglobulin G4-related systemic disease can spread to nearly every organ, and often presents as an inflammatory mass or masses at those sites. In the kidney, this disease is often diagnosed after a radical or partial nephrectomy following the discovery of an inflammatory mass which is often suspected to be a malignant tumor. Here, we present a rare case of inflammatory pseudotumors of the kidney and the lung presenting as immunoglobulin G4-related disease, which were diagnosed by computed tomography-guided biopsies.
  
  
  METHODS
  A 54-year-old Japanese man was referred to our hospital with suspected bilateral renal cancer, multiple lung metastases and autoimmune pancreatitis. His serum immunoglobulin G4 level was high. We used computed tomography-guided biopsies and histopathological examinations of the biopsied specimens to diagnose the tumors as immunoglobulin G4-related bilateral renal and lung inflammatory pseudotumors. Our patient was treated with oral prednisolone, and after one month of treatment, contrast-enhanced computed tomography demonstrated a general improvement, as noted by a reduction in size of the masses.
  
  
  CONCLUSIONS
  Renal masses that are formed due to immunoglobulin G4-related disease require comprehensive diagnosis to prevent unnecessary surgical resections from being performed. Further consideration should be paid to immunoglobulin G4-related diseases in the future.
authors.affiliation: Department of Urology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan. genchari@aichi-med-u.ac.jp.
authors.forename: Genya
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authors.lastname: Nakamura
authors.forename: Yoshiaki
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authors.forename: Takahiko
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authors.lastname: Yoshizawa
authors.forename: Yoshiharu
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authors.forename: Shigeyuki
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authors.forename: Tomohiro
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authors.lastname: Taki
authors.forename: Nobuaki
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authors.lastname: Honda