SP100 and primary biliary cholangitis: While additional AMA-negative PBC patients can be identified by the presence of anti-sp100 corresponding to the multiple nuclear dot pattern by IIF on HEp-2 cells (AC-6 according to International Consensus of ANA patterns, ICAP), anti-gp210 punctate nuclear envelope by IIF on HEp-2 cells (AC-12 according to ICAP), and anti-p62 antibodies, some PBC patients remain seronegative, potentially resulting in delayed diagnosis and treatment (10–14).