Background and study aims: Antimitochondrial antibody (AMA)-negative primary biliary cirrhosis (PBC) has been difficult to diagnose. Laparoscopic features of AMA-negative PBC were evaluated in comparison with those of AMA-positive PBC and autoimmune hepatitis. Patients and methods: 71 patients who fulfilled the diagnostic criteria for PBC were enrolled in the study; 48 were AMA-positive and 23 were AMA-negative. As a disease control, 46 autoimmune hepatitis patients were included. Both the frequency and specificity of each laparoscopic finding were evaluated. A laparoscopic scoring system was introduced, which used, common and uncommon laparoscopic findings, and was evaluated for the diagnosis of AMA-negative PBC. Results: The characteristic laparoscopic findings for AMA-positive PBC were yellowish-white marking (92%), dark-brown discoloration (73%), gentle undulation (67%), reddish patch (38%), and yellowish-white nodules (32%). On the other hand, laparoscopic findings such as trench-like depression, reddish markings, and wide and small depressions were uncommon in PBC compared with autoimmune hepatitis. The frequencies of characteristic and uncommon laparoscopic findings did not differ statistically between AMA-positive and AMA-negative PBC, but were different between AMA-positive or AMA-negative PBC and autoimmune hepatitis. Scores based on common and uncommon laparoscopic findings were 5.5 ± 1.5 (mean ± SD) in AMA-positive PBC, 5.6 ± 2.0 in AMA-negative PBC, and -0.30 ± 0.5 in autoimmune hepatitis. Conclusion: The laparoscopic findings in AMA-negative PBC did not differ from those of AMA-positive PBC. A laparoscopic scoring system may be helpful in the diagnosis of AMA-negative PBC.
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