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
Scarring:
(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.)
