Correct!
1. IgG4 – sclerosing disease
The renal lesion could be a primary malignancy- the appearance, with focal central low attenuation and foci of calcification is, however, atypical for that diagnosis. The appearance of the lung lesion is atypical for metastatic malignancy. Typically metastatic lesions are circumscribed, or, when hemorrhagic, may have poorly defined borders, but rarely will metastatic disease to the lungs present with such prominent air bronchograms. Given the low attenuation in the renal lesion, and renal abscess is a consideration, although the patient’s history does not support that diagnosis. The lung lesion’s appearance, however, is not suggestive of septic embolization. Septic emboli typically appear as multiple, bilateral, peripheral poorly defined opacities that fairly rapidly undergo cavitation; air bronchograms are not a typical feature of septic emboli. Furthermore, no renal vein thrombosis was noted at abdominal imaging. Vasculitis with combined pulmonary, renal, and aortic involvement is a good consideration when attempting to link pathology among these three organ systems, but the imaging appearances in this patient are not typical of vasculitis affecting these organs. Vasculitis in the lung typically appears as peripheral poorly defined nodules or masses that cavitate, or multifocal ground-glass opacity, reflecting hemorrhage; a solitary nodule or mass with air bronchograms is not suggestive of vasculitis. Vasculitis involving the aorta usually appears as concentric wall thickening, rather than the eccentric thickening seen in this patient {although this pattern can occur with vasculitis). Finally, renal involvement with vasculitis does not typically appear as a focal mass-like lesion and is commonly bilateral, rather than unilateral. Although uncommon, IgG-4 related disease is the entity that could potentially explain the pulmonary, renal, and aortic lesions in this patient.).
The patient’s renal biopsy showed storiform (resembling the spokes of a cartwheel with spindle cells radiating from a center) proliferative fibrosis with extensive inflammation, including numerous plasma cells. IgG and IgG-4 immunohistochemical stains highlighted greater than 30 IgG-4 plasma cells / high power field, with one-third of the plasma cells found to be IgG-4 positive. No glomerulonephropathy was seen. The diagnosis was therefore IgG-4 tubulo-interstitial nephritis.
The patient was considered to have IgG-4 related disease, and this disorder was thought to potentially explain all the imaging findings. The patient was begun on 40 mg prednisone / day. The patient was re-imaged 2 months later, and regression of the biliary tract thickening, renal lesion, aortic thickening, and lung lesion (Figure 5) had either completely or nearly completely resolved.
Figure 5. Video of the repeat thoracic/abdominal CT scan 2 months after the first CT scan showing regression of the biliary tract thickening, renal lesion, aortic thickening, and lung lesion.
Diagnosis: IgG-4 related disease
References