31 May 2025
: Case report 
Granulomatosis with Polyangiitis Presenting as Pancreatic Pseudotumor and Peripancreatic Lymphadenitis: Diagnostic Challenges and Review of 55 Cases
Mistake in diagnosis, Unusual or unexpected effect of treatment, Diagnostic / therapeutic accidents, Rare disease, Educational Purpose (only if useful for a systematic review or synthesis)
Camille Beniada ABCEF 1, Yann Coattrenec AE 1, Sahar Mack
ADEF 2, Alexis Ricoeur CD 3, Volkan Adsay CD 4,5, Giacomo Puppa DE 6, Jörg D. Seebach ACDEF 1*
DOI: 10.12659/AJCR.945741
Am J Case Rep 2025; 26:e945741
Table 3 Comparison of autoimmune pancreatitis subtypes and pancreatic disease associated with GPA and MPA.
| Feature | Pancreatic GPA | MPA (microscopic polyangiitis) | Type 1 AIP (IgG4-related) | Type 2 AIP |
|---|---|---|---|---|
| Granulomas | Present, necrotizing granulomas (often poorly formed) | Absent | Absent | Absent |
| Vasculitis | Necrotizing vasculitis of small/medium vessels | Necrotizing vasculitis of small vessels | Obliterative phlebitis | No vasculitis |
| Inflammatory cells | Neutrophils (vasculitis), mononuclear and multi-nucleated giant cells (granulomas) | Predominantly neutrophils and monocytes | Lymphoplasmacytic infiltrate | Neutrophilic infiltration of ducts |
| IgG4-positive plasma Cells | Absent or rare | Absent | Marked increase in IgG4-positive plasma cells | Absent |
| Ductal involvement | May show periductal inflammation and destruction but less pronounced | May show minimal ductal involvement | Strictures or narrowing with periductal inflammation and fibrosis | Granulocytic epithelial lesions (GELs), ductal destruction |
| Fibrosis | Moderate to severe fibrosis, especially around granulomas | Minimal to moderate fibrosis | Severe periductal fibrosis, storiform fibrosis | Limited fibrosis |
| ANCA testing | ANCA-positive, predominantly anti-PR3 | ANCA-positive, predominantly anti-MPO | ANCA-negative | ANCA-negative, rarely atypical p-ANCA |
| Associated conditions | Often with systemic involvement (ENT, renal, pulmonary, skin) | Commonly associated with renal and pulmonary issues, no ENT involvement | Sclerosing cholangitis, ENT involvement, periaortitis, retroperitoneal fibrosis | Often associated with IBD, mainly ulcerative colitis |