IgA nephropathy in two patients with Sjögren's syndrome: one with concomitant autoimmune hepatitis

Concurrent glomeruli and liver involvement in patients with Sjögren's syndrome (SS) has seldom been reported. Meanwhile, IgA nephropathy (IgAN) associated with SS is not as common as other types of glomerulonephritis, such as membranoproliferative glomerulonephritis (MPGN) and membranous nephropathy (MN). Two patients with SS and IgAN are presented. Case 1 was diagnosed as SS complicated with IgAN (Haas subclass III) and severe AIH, while case 2 was diagnosed as SS and IgAN (Haas subclass I) with serious tubulointerstitial lesions. The true prevalence of IgAN secondary to SS is certainly underestimated and the crucial pathogenetic factors may be polyclonal hypergammaglobulinemia and hypocomplementemia (especially C4). The frequent presence of multiple immunoglobulin and complement deposition in glomeruli, especially weak deposits of C4 and (or) C1q, is an immunofluorescence staining feature of IgAN secondary to SS and may be associated with disease severity and activity.