Episode three steps outside the alcohol-and-tobacco gland to a diagnosis that sits at a costly decision point: steroids given to a patient who actually has adenocarcinoma cost the curative resection window. Autoimmune pancreatitis splits on mechanism, type one a systemic IgG4-related plasma-cell disease of older men with painless jaundice, type two a duct-centered process a decade younger tied to inflammatory bowel disease. Demographics, imaging, serology, other-organ involvement, and histology all line up behind that one distinction, and the criteria are structured precisely because the mass mimics cancer. The steroid trial is pulled in as a diagnostic element, but when the differential with adenocarcinoma stays genuinely unresolved, surgery comes first. Mechanism drives the whole call. Topics covered Mechanism split: plasma-cell versus duct-centered Demographics of type one and type two Imaging and the absent double-duct sign IgG4 serology and its threshold Other-organ involvement Histology: storiform fibrosis versus granulocytic lesion Steroid response as a diagnostic element When surgery precedes the steroid trial Relapse pattern and rituximab Key decisions Type one is a systemic IgG4-related plasma-cell disease of older men presenting with painless obstructive jaundice, while type two is a duct-centered process a decade younger with an even sex distribution and an inflammatory bowel disease association in about a third. Adenocarcinoma produces the double-duct sign with upstream dilation, whereas type one infiltrates and narrows the duct without dilating it, so a sausage-shaped gland with a capsule rim and a non-dilated duct nearly makes the diagnosis. A mild IgG4 elevation under twofold also occurs in some pancreatic cancers, so only a value greater than two times the upper limit of normal supports autoimmune pancreatitis, and even then it is one criterion among several. Both types respond to prednisone forty milligrams daily for four weeks then a five-milligram weekly taper, with clinical and biochemical improvement within two weeks part of the criteria and failure to respond the signal to re-evaluate for cancer. When the noninvasive workup leaves the differential with adenocarcinoma genuinely unresolved, a focal head mass with a double-duct sign, a high CA 19-9, a mildly elevated IgG4, and non-diagnostic histology goes to resection, not empiric steroids. Type one relapses in a third to a half of patients, so rituximab one thousand milligrams on days one and fifteen with maintenance every six months for two years is the steroid-sparing agent of choice. Type two rarely relapses because there is no circulating clone, so no maintenance is indicated and the rare relapse is treated like the first episode. For the full chapter with MCQs, tables, and primary-guideline references, visit www.boardpearls.com. Questions or feedback: [email protected].

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“What did the council decide on item 42?” — answered with the speaker and the moment.

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