IgG4-related disease and ANCA positive vasculitis in childhood: a case-based review.

Autoimmune pancreatitis (AIP) type 1 is an IgG4-related disease (IgG4-RD), characterized by inflammatory pseudotumors and histologically by dense lymphoplasmacytic infiltrates rich in IgG4 positive plasma cells, storiform fibrosis, and obliterative phlebitis. Although quite rare, IgG4-RD was found to be associated with medium or small vessel vasculitides. A new overlap syndrome between IgG4-RD and ANCA-associated vasculitis (AAV) has recently been described in the adult population. Here we present a 16-year-old adolescent girl admitted with abdominal pain, episcleritis, palpable purpura, salivary gland enlargement, and bloody diarrhea. Laboratory investigations revealed findings of glomerulonephritis. Abdominal imaging surprisingly revealed a focal mass in the pancreatic tail, while the c-ANCA level was found to be quite high as well as serum IgG4 level. Biopsy of the pancreatic mass showed lymphoplasmacytic IgG4 positive cells infiltrating the pancreas with storiform fibrosis compatible with IgG4-related AIP. The renal biopsy that was done simultaneously showed necrotizing granulomatous vasculitis indicating AAV. Renal biopsy showed IgG4 positive plasma cells very rarely by immunohistochemical examination, which does not indicate any significance for IgG4-RD. Our diagnosis was IgG4-related AIP and AAV overlap syndrome, which has not been reported in the pediatric populations yet. IgG4-RD should be investigated in patients with ANCA-associated vasculitis who shows atypical organ involvement. We searched the Pubmed/Medline and Google Scholar databases to identify clinical findings, treatment, and outcome of the patients with IgG4-related AIP and AAV.