[1576] Necrotizing Arteritis Presenting as a Pancreatic Mass: A New Addition to the Immune-Related Tumoral Pancreatitides

AB Farris, I Coban, DS Klimstra, G Kim, V Deshpande, N Ohike, N Adsay. Emory U, Atlanta; Memorial-Sloan Kettering Cancer Center, New York; UCSF, San Francisco; Massachusetts General Hospital, Boston

Background: Autoimmune pancreatitis (AIP) has thus far been categorized in two distinct subtypes: 1) IgG4-related lymphoplasmacytic-sclerosing (LPSP), often associated with exocrine organ disease such as Sjögren, and 2) granulocytic-epithelial lesion(GEL)-forming (idiopathic duct-centric), often associated with ulcerative colitis and related conditions. Here we present 4 examples of a distinct subset characterized by arteritis and lacking the stigmata of the other 2 types.
Design: Clinicopathologic features of these 4 cases were analyzed. Reviewed separately were pancreatic sections from 41 resected ordinary AIPs and 28 collagen vascular disease (CVD) autopsies.
Results: Study group patients (2 male, 2 female) underwent resection with a clinical suspicion of adenocarcinoma (3 pancreatoduodenectomies, 1 distal pancreatectomy). They had mean age of 60 and presented with abdominal pain (n = 2) and jaundice (n = 1). Microscopically, all had arteritis with focal fibrinoid necrosis in pancreatic parenchymal large and medium-sized arteries. No GEL formation was noted. None had classical stigmata of LPSP such as storiform fibrosis. Three cases had relatively mild inflammation. Acinar lobules were well-preserved. There were no (n = 2) or only focal (n = 2) plasmacytic infiltrates including a systemic lupus erythematosus (SLE) case in which inflammation spared the ducts. SLE and psoriasis were present in 2 cases and 1 case, respectively, and a 4th case was lost to follow up. In CVD autopsy cases, 6/28 showed focal pancreatic vasculitis but no associated pancreatic injury. Among 41 ordinary AIP cases, 3 had focal arterial involvement amidst abundant periarterial inflammation [regarded as 2°, not 1° vasculitis].
Conclusions: This rare but distinct sub-type of AIP is characterized by arteritis and a lack of the classical stigmata of LPSP and GEL-forming AIP categories. This arteritic-type AIP appears to be associated with CVDs such as SLE. Further studies are warranted to clarify this sub-type's nature and its association with other variants.

Category: Liver & Pancreas

Tuesday, March 23, 2010 1:15 PM

Platform Session: Section C, Tuesday Afternoon


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