Certain histopathologic features may be found in a patient with autoimmune pancreatitis. These findings are not diagnostic but can be supportive for the diagnosis.


Factors affecting interpretation:

(1) duration of disease (fibrosis increases with chronic disease)

(2) corticosteroid or immunosuppressive therapy (reduce inflammation)


Inflammatory findings:

(1) diffuse lymphoplasmacytic inflammation, which may be mild to marked in intensity

(2) periductal inflammation

(3) perineural inflammation

(4) venulitis and obstructive phlebitis



(1) diffuse fibrosis

(2) acinar atrophy


Variable findings:

(1) inflammatory pseudotumor (dense proliferation of spindle and chronic inflammatory with collagen)

(2) periductal granulomas without pathogens


Relative exclusions:

(1) evidence of benign or malignant neoplasm

(2) organisms seen in periductal granulomas

(3) other cause that can explain the findings better (tumor at the ampulla with obstruction, etc.)


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