Abstract

BACKGROUND
Idiopathic duct centric pancreatitis (IDCP) is a subtype of autoimmune pancreatitis (AIP) that is histologically characterized by granulocytic epithelial lesion and scarce IgG4-positive cells. This subtype of AIP has not been documented in Asian countries.
METHODS
We reviewed 38 histologically confirmed AIP cases and classified them into lymphoplasmacytic sclerosing pancreatitis (LPSP) and IDCP. Then, clinicopathological characteristics were compared between LPSP and IDCP.
RESULTS
Fourteen cases (36.8%) were IDCP. IDCP affected younger patients more than LPSP. IDCP was associated with ulcerative colitis in 35.7% of cases, whereas LPSP was associated with IgG4-related sclerosing diseases such as cholangitis, retroperitoneal fibrosis or sialadenitis in 41.7% of cases. IDCP was microscopically characterized by neutrophilic ductoacinitis with occasional granulocytic epithelial lesions, whereas LPSP was characterized by storiform inflammatory cell-rich fibrosis and obliterative phlebitis. IgG4-positive cells were not detected in any IDCP case but more than 20 IgG4-positive cells per high-power-field were invariably detected in LPSP cases. All patients with IDCP responded dramatically to steroids without recurrence, whereas 33.3% of patients with LPSP developed recurrences.
CONCLUSIONS
IDCP is clinicopathologically distinct from LPSP and can be diagnosed when neutrophilic ductoacinitis or granulocytic epithelial lesions are observed in a pancreatic biopsy under the appropriate clinical setting.

• Keywords: Autoimmune pancreatitis;Idiopathic duct centric pancreatitis;Granulocytic epithelial lesion;Biopsy, Needle