Henoch-Schönlein purpura nephritis in a patient with IgG4-related disease: A possible association

We report a case of Henoch- Schönlein purpura nephritis (HSPN) associated with tubulointerstitial nephritis (TIN) and chronic sclerosing sialoadenitis. The patient is a 75-year-old Japanese woman who had bilateral submandibular gland swelling, palpable purpura on the lower legs, and decreased renal function with hematoproteinuria and marked hypocomplementemia, but no skin lesion suggestive of systemic lupus erythematosus (SLE), and did not fulfill the classification criteria for SLE. Her serum IgG4 level was high and immunostaining of renal biopsies revealed marked infiltration by IgG4-positive plasma cells in the interstitium, confirming the diagnosis of IgG4- related disease. On the other hand, glomeruli showed endocapillary proliferative glomerulonephritis with mesangial IgA and C3 deposition demonstrated by immunofluorescence staining, which were typical glomerular lesions for HSPN. The glomerular and tubulointerstitial lesions responded to steroid therapy dramatically, and her renal function recovered to within the normal range within a month. This case suggests a possible new association between HSPN and IgG4-related disease.