Incidentally Discovered HCC (iHCC) in Explant Liver-Histopathologic Features and Clinical Outcome

Incidentally discovered hepatocellular carcinomas (iHCC) are tumors which are discovered on the explanted liver which were not present on imaging prior to transplant. The natural history, histopathologic characteristics and prognosis of iHCC are not clearly defined. Methods: A retrospective analysis was performed to compare the characteristics of iHCC and established HCC within Milan criteria (eHCC) in patients who underwent liver transplantation at our center between 2000 and 2010. Results: During the study period a total of 975 adult patients were transplanted in our center; 124 (12.7%) patients had eHCC and 26 (2.6%) patients had iHCC. A larger number of patients with iHCC (73.1%) had ascites when compared to eHCC (41.3%) (p = 0.035). Patients with iHCC had a higher mean bilirubin (p 0.001) and mean INR (p = 0.05) than patients with eHCC. Around 70% of patients with iHCC had a Model for End Stage Liver Disease (MELD) score greater than 15 at the time of listing while only 25% of patients with eHCC had a MELD greater than 15 at listing (p 0.001).The mean alphafetoprotein (AFP) in patients with iHCC was significantly lower (11.6 ± 16.5) than the patients with eHCC (564.9 ± 2180; p = 0.024). In patients with iHCC, 30.8% had a multiple tumors and 23% had bilobar involvement. The average number of tumors was 1.6 and the cumulative tumor size was 2.1 cm (SD 1.4). The cumulative tumor size in iHCC was significantly smaller than in eHCC (mean 3.9 cm) (p = 0.035). American Joint Committee on Cancer (AJCC) T1 tumor stage was found in 58% of patients with iHCC and 48.4% of patients with eHCC (p = 0.829).The median survival was 9.47 years for iHCC (95% CI 7.0 - 11.9) and 8.7 years (95% CI 6.1 - 11.4) for eHCC (p = 0.328). While none of the patients with iHCC had recurrence of HCC, the incidence of recurrence in patients with eHCC was 6.4%. Conclusion: iHCC occurred in patients with more advanced liver disease than eHCC. AFP was usually not elevated in patients with iHCC. The cumulative tumor size of iHCC was smaller than eHCC but around a third of iHCC were multifocal, supporting the theory of multicentric hepatic carcinogenesis. Survival of patients with iHCC was similar to patients with eHCC and recurrence was not noted in patients with iHCC.