MLH1 and thymoma: Figure 6 shows that the immunostaining patterns of EGFR, c-erbB-2 and p53 in type AB thymoma and thymic carcinoma were similar, but there was greater MLH1 and MSH2 loss in thymic carcinoma (>10%) than in type AB thymoma (<10%), which indicates the presence of microsatellite instability in thymic carcinoma but not type AB thymoma.