Immunoglobulin G4 (IgG4)-related kidney disease (IgG4-KD) has recently been demonstrated to be an important part of IgG4-related sclerosing disease (IgG4-SD). However, since IgG4-KD is still relatively unfamiliar to radiologists and physicians as compared to IgG4-SD involving other organs, it could, therefore, be easily missed. In this article, we present a comprehensive pictorial review of IgG4-KD with regards to the imaging spectrum, mimickers, and clinicopathologic characteristics, based on our clinical experience with 48 patients during the past 13 years, as well as a literature review. Awareness of the broad imaging spectrum of IgG4-KD and differential diagnosis from its mimickers will thus facilitate its early diagnosis and treatment.
Adult ; Aged ; Aged, 80 and over ; Autoimmune Diseases/pathology/radiography ; Female ; Humans ; Immunoglobulin G/*metabolism ; Kidney Diseases/drug therapy/*pathology/radiography ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Steroids/therapeutic use ; Tomography, X-Ray Computed

After 4-months of alpha interferon (IFN-alpha), a 64-year old woman with chronic hepatitis C developed a cough and dyspnea and showed diffuse infiltrative opacities on her chest X-ray. Her symptoms persisted after stopping the IFN-alpha therapy. Pulmonary function testing revealed a reduced forced vital capacity. High-resolution computed tomography of the lung showed peripheral and peribronchovascular ground glass attenuation and consolidation associated with reticulation. Bronchoalveolar lavage was performed for further evaluation and showed a lymphocyte level of 8.2%, an uncommon finding in IFN-alpha-induced interstitial pneumonitis. We performed a lung biopsy to diagnose her disease and it suggested interstitial pneumonitis. This was considered to be due to the immunomodulatory effects of INF-alpha. Although rare, any sign of significant pulmonary involvement should be evaluated.
Antiviral Agents/*adverse effects/therapeutic use ; Bronchoalveolar Lavage ; Female ; Hepatitis C, Chronic/complications/*drug therapy ; Humans ; Interferon-alpha/*adverse effects/therapeutic use ; Kidney Failure, Chronic/complications ; Lung Diseases, Interstitial/*chemically induced/pathology/radiography ; Middle Aged ; Respiratory Function Tests ; Tomography, X-Ray Computed