Background & Aims: Little is known about subjects with idiopathic tumefactive chronic pancreatitis (TCP), that is, chronic pancreatitis whose clinical presentation, usually with a mass or obstructive jaundice, suggests cancer. Methods: We independently reviewed clinical data and histology of 45 TCP (27 idiopathic, 18 alcohol induced) resected at Mayo Clinic (January 1985-March 2001). Follow-up data were obtained from medical records and mailed questionnaires. Results: Compared with alcoholic subjects, idiopathic TCP patients were older (58 ± 2 vs. 48 ± 3 yr, P < 0.001), had shorter symptom duration (median 3 vs. 24 wk, P < 0.001), were more likely to have no or mild abdominal pain (70% vs. 17%, P = 0.001), and were more often jaundiced (67% vs. 33%, P = 0.02). Three distinct histologic patterns were identified in TCP. Typical CP (n = 19) showed lobular atrophy, fat necrosis, and ductal changes (dilatation, protein plugs, and stones). Lymphoplasmacytic sclerosing pancreatitis (LPSP) (n = 14) was characterized by periductal lymphoplasmacytic infiltration, obliterative phlebitis, and cholangitis with edema. Idiopathic duct-centric CP (IDCP) (n = 12) had neutrophil-predominant lobular inflammation, without phlebitis. On correlation of clinical and histologic diagnosis, 17 of 18 (94%) patients with alcohol-induced TCP had typical CP, and 25 of 27 (93%) with idiopathic TCP had LPSP or IDCP. LPSP and IDCP were indistinguishable clinically except for higher incidence of jaundice in LPSP (93% vs. 42%, P = 0.005). In idiopathic TCP no recurrence of symptoms was observed after resection (median follow-up 49 mo). Conclusions: Idiopathic TCP is clinically and histologically distinct from alcohol-induced TCP. It is unclear whether LPSP and IDCP, 2 unique patterns of histologic injury observed in idiopathic TCP, are part of the spectrum of the same disease or represent 2 or more different entities. Resection of mass prevents recurrence of symptoms in idiopathic TCP.
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