{"id":175,"date":"2026-07-01T07:52:45","date_gmt":"2026-07-01T07:52:45","guid":{"rendered":"https:\/\/blogs.imperial.ac.uk\/my-path\/?p=175"},"modified":"2026-07-01T07:53:36","modified_gmt":"2026-07-01T07:53:36","slug":"bsep-bile-salt-export-pump-immunohistochemistry","status":"publish","type":"post","link":"https:\/\/blogs.imperial.ac.uk\/my-path\/2026\/07\/01\/bsep-bile-salt-export-pump-immunohistochemistry\/","title":{"rendered":"BSEP (Bile Salt Export Pump) Immunohistochemistry"},"content":{"rendered":"<p class=\"font-claude-response-body break-words whitespace-normal\">Bile Salt Export Pump (BSEP) is an ATP-binding cassette transporter protein (encoded by <em>ABCB11<\/em>) that functions as the major canalicular bile salt transporter in hepatocytes. In diagnostic pathology, BSEP IHC is used primarily as a canalicular marker for hepatocellular carcinoma and in the diagnosis of bile salt export pump deficiency in progressive familial intrahepatic cholestasis type 2 (PFIC2).<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\"><strong>Hepatocellular carcinoma<\/strong><\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\">BSEP shows a canalicular (&#8220;chicken-wire&#8221;) staining pattern in tumour cells, reflecting its normal physiological role as a bile salt transporter. This pattern confirms hepatocellular differentiation and helps distinguish HCC from metastatic adenocarcinoma or cholangiocarcinoma, neither of which forms canaliculi and therefore won&#8217;t show this staining pattern.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\">BSEP functions conceptually alongside other canalicular markers such as polyclonal CEA and CD10, and is generally considered more sensitive and specific than pCEA in some series.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\">Loss or reduction of BSEP staining has also been reported in poorly differentiated HCC and in some cholestatic hepatocellular lesions, so absent staining isn&#8217;t specific on its own \u2014 pattern interpretation in context matters.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\"><strong>Progressive Familial Intrahepatic Cholestasis Type 2<\/strong><\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\">PFIC2 results from biallelic <em>ABCB11<\/em> mutations. Liver biopsy IHC typically shows absent or markedly reduced canalicular BSEP staining, supporting the diagnosis alongside clinical\/biochemical features (low-GGT cholestasis, elevated bile acids) and molecular confirmation.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\">A useful nuance: some <em>ABCB11<\/em> missense mutations produce a mistrafficked but partially functional protein, which can show weak\/patchy canalicular staining or an intracellular rather than purely canalicular pattern \u2014 so BSEP IHC is supportive but not strictly binary, and genetic testing remains the gold standard.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal\">PFIC2 patients with BSEP deficiency also carry an increased risk of hepatocellular carcinoma and cholangiocarcinoma at a young age, which is relevant when assessing paediatric explant or resection specimens.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Bile Salt Export Pump (BSEP) is an ATP-binding cassette transporter protein (encoded by ABCB11) that functions as the major canalicular bile salt transporter in hepatocytes. In diagnostic pathology, BSEP IHC is used primarily as a canalicular marker for hepatocellular carcinoma and in the diagnosis of bile salt export pump deficiency in progressive familial intrahepatic cholestasis [&hellip;]<\/p>\n","protected":false},"author":1119,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[289779,1],"tags":[318396],"class_list":["post-175","post","type-post","status-publish","format-standard","hentry","category-hepato-biliary-pathology","category-uncategorized","tag-consultant"],"_links":{"self":[{"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/posts\/175","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/users\/1119"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/comments?post=175"}],"version-history":[{"count":1,"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/posts\/175\/revisions"}],"predecessor-version":[{"id":176,"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/posts\/175\/revisions\/176"}],"wp:attachment":[{"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/media?parent=175"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/categories?post=175"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.imperial.ac.uk\/my-path\/wp-json\/wp\/v2\/tags?post=175"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}