Clonal analysis of micronodules in virus C-induced liver cirrhosis using laser capture microdissection (LCM) and HUMARA assay

Most hepatocellular carcinomas (HCC) arise from malignant transformation of regenerative cirrhotic nodules. Because HCC has a very poor prognosis, det ection of these premalignant lesions may improve the management of patients with cirrhosis. In this regard, clonal analysis of liver micronodules shou ld be of particular interest in order to differentiate polyclonal regenerat ive micronodules from monoclonal neoplastic potentially malignant micronodu les. To address this issue, 112 micronodules from 15 cases of explanted liv er cirrhosis were carefully microdissected from paraffin-embedded tissue us ing a laser capture microscopy system. Clonal analysis was performed by ana lyzing X-chromosome inactivation, as indicated by the methylation status of the human androgen receptor gene (HUMARA). For each microdissected microno dule, a large set of pathological features was evaluated and correlated wit h their clonal status. Clonal analysis showed that 57 micronodules (51%) we re monoclonal and 55 (49%) were polyclonal. Prevalence of monoclonal nodule s ranged from 25% to 71% according to cases. In all cases, mono- and polycl onal nodules were randomly distributed in the cirrhotic liver. Although the clonal status was not significantly affected by the presence or absence of macronodules in the adjacent liver, size of monoclonal micronodules was si gnificantly larger than size of polyclonal micronodules (mean size of the m onoclonal nodules: 3 + 0.1 mm vs mean size of the polyclonal nodules: 2.5 /- 0.1 mm, p = 0.007). Among the elementary pathological features evaluated , only the presence of iron overload was correlated with a monoclonal statu s (p = 0.04). In conclusion, clonal analysis of liver cirrhosis shows that 51% of micronodules are monoclonal lesions, supporting the notion that live r cirrhosis is a multineoplastic lesion. Because monoclonality is a marker of neoplasia, cirrhosis with accumulation of monoclonal nodules may be care fully followed, and monoclonal nodules should be screened for additional ma rkers to assess their biological behavior.