Editing Primary sclerosing cholangitis (section)

==Diagnosis==
[[File:CT of primary sclerosing cholangitis.jpg|thumb|[[CT scan]] findings in a case of primary sclerosing cholangitis]]
[[File:Sclerosing cholangitis 0001.jpg|thumb|Ultrasound of sclerosing cholangitis in the common bile duct]]
PSC is generally diagnosed on the basis of having at least two of three clinical criteria after secondary causes of sclerosing cholangitis have been ruled out:{{cn|date=September 2022}}
* serum [[alkaline phosphatase]] (ALP) > 1.5x the upper limit of normal for longer than 6 months
* cholangiography demonstrating biliary strictures or irregularity consistent with PSC
* liver biopsy consistent with PSC (if available)

Historically, a cholangiogram would be obtained via [[endoscopic retrograde cholangiopancreatography]] (ERCP), which typically reveals "beading" (alternating strictures and dilation) of the bile ducts inside and/or outside the liver. Currently, the preferred option for diagnostic cholangiography, given its noninvasive yet highly accurate nature, is [[magnetic resonance cholangiopancreatography]] (MRCP), a [[magnetic resonance imaging]] technique.  MRCP has unique strengths, including high spatial resolution, and can even be used to visualize the [[biliary tract]] of small animal models of PSC.<ref>{{cite journal | vauthors = Tabibian JH, Macura SI, O'Hara SP, Fidler JL, Glockner JF, Takahashi N, Lowe VJ, Kemp BJ, Mishra PK, Tietz PS, Splinter PL, Trussoni CE, LaRusso NF | display-authors = 6 | title = Micro-computed tomography and nuclear magnetic resonance imaging for noninvasive, live-mouse cholangiography | journal = Laboratory Investigation; A Journal of Technical Methods and Pathology | volume = 93 | issue = 6 | pages = 733–743 | date = June 2013 | pmid = 23588707 | pmc = 3875307 | doi = 10.1038/labinvest.2013.52 }}</ref>

Most people with PSC have evidence of [[autoantibodies]] and abnormal immunoglobulin levels.<ref>{{cite journal | vauthors = Tabibian JH, Enders F, Imam MH, Kolar G, Lindor KD, Talwalkar JA | title = Association between serum IgE level and adverse clinical endpoints in primary sclerosing cholangitis | journal = Annals of Hepatology | volume = 13 | issue = 3 | pages = 384–389 | year = 2014 | pmid = 24756015 | pmc = 4215553 | doi = 10.1016/S1665-2681(19)30869-5 }}</ref> For example, approximately 80% of people with PSC have perinuclear [[Anti-neutrophil cytoplasmic antibody#p-ANCA|antineutrophil cytoplasmic antibodies]] (P-ANCA); however, this and other immunoglobulin findings are not specific to those with PSC and are of unclear clinical significance/consequence. [[Antinuclear antibodies]] and [[anti-smooth muscle antibody]] are found in 20–50% of PSC patients, and likewise are not specific for the disease, but may identify a subgroup of PSC patients who also have autoimmune hepatitis (i.e. PSC-AIH overlap syndrome).<ref name=Charatchar/>

The differential diagnosis can include primary biliary cholangitis (formerly referred to as [[primary biliary cirrhosis]]), drug-induced [[cholestasis]], [[cholangiocarcinoma]], [[IgG4-related disease]], post-liver transplantation nonanastomotic biliary strictures,<ref>{{cite journal | vauthors = Tabibian JH, Asham EH, Goldstein L, Han SH, Saab S, Tong MJ, Busuttil RW, Durazo FA | display-authors = 6 | title = Endoscopic treatment with multiple stents for post-liver-transplantation nonanastomotic biliary strictures | journal = Gastrointestinal Endoscopy | volume = 69 | issue = 7 | pages = 1236–1243 | date = June 2009 | pmid = 19249040 | doi = 10.1016/j.gie.2008.09.057 }}</ref>  and [[HIV]]-associated cholangiopathy.<ref>{{cite journal | vauthors = Lazaridis KN, LaRusso NF | title = The Cholangiopathies | journal = Mayo Clinic Proceedings | volume = 90 | issue = 6 | pages = 791–800 | date = June 2015 | pmid = 25957621 | pmc = 4533104 | doi = 10.1016/j.mayocp.2015.03.017 }}</ref> Primary sclerosing cholangitis and primary biliary cholangitis are distinct entities and exhibit important differences, including the site of tissue damage within the liver, associations with IBD, which includes ulcerative colitis and Crohn's disease, response to treatment, and risks of disease progression.<ref>{{cite journal | vauthors = Trivedi PJ, Corpechot C, Pares A, Hirschfield GM | title = Risk stratification in autoimmune cholestatic liver diseases: Opportunities for clinicians and trialists | journal = Hepatology | volume = 63 | issue = 2 | pages = 644–659 | date = February 2016 | pmid = 26290473 | pmc = 4864755 | doi = 10.1002/hep.28128 }}</ref>

===Classification===
Primary sclerosing cholangitis is typically classified into three subgroups based on whether the small and/or large bile ducts are affected. The subgroups of PSC include:<ref name="Lazaridis2016" />
* Classic PSC
* Small-duct PSC
* PSC associated with [[autoimmune hepatitis]]