Immunoglobulin type gamma 4 (IgG4)-related disease is a relatively newly described clinical entity characterized by a distinctive histopathological appearance, increased numbers of
IgG4 positive plasma cells and often, but not always, elevated serum
IgG4 concentrations. The most common renal manifestation of
IgG4-related disease is
tubulointerstitial nephritis marked with
proteinuria,
hematuria, decreased kidney function, hypocomplementemia, and radiologic abnormalities. Renal biopsy characteristics include dense lymphoplasmacytic
tubulointerstitial nephritis that stains for
IgG4, storiform
fibrosis, and
immune complex deposition in the interstitium and along tubule basement membranes. Treatment traditionally consists of prolonged
glucocorticoids but cases refractory to
glucocorticoids have been reported.We report a case of a 58-year-old Caucasian man who presented with
fatigue, 50 pound
weight loss,
dyspnea,
lymphadenopathy, and nephromegaly. The patient was first misdiagnosed as chronic
interstitial nephritis secondary to renal sarcoid and was treated with repeated doses of
prednisone. On his third relapse, he underwent a repeat renal biopsy and a diagnosis of IgG4-tubulointerstitial
nephritis was confirmed. He was refractory to treatment with
prednisone. The patient received
Rituximab and had prompt sustained improvement in renal function. At 1 year post
Rituximab treatment, his serum
creatinine remains at baseline and imaging study revealed reduction in his kidney size.This is the first case report using
Rituximab as a
steroid sparing option for refractory IgG4-tubulointerstitial
nephritis. More information is needed on the long-term effects of using of B-cell depleting agents for
glucocorticoid resistant IgG4-tubulointerstitial
nephritis.