KRT18 and pachyonychia congenita: Cells detected in our study in PC patients can be divided into five categories in terms of the iFISH results: (1) type-A phenotype: CK18−, CD45−, DAPI+, CEP-8≠2 (Figure 2A); (2) type-B phenotype: CK18+, CD45−, DAPI+ (Figure 2B); (3) type-C phenotype: CK18−, CD45+, DAPI+ (Figure 2C); (4) type-D phenotype: CK18−, CD45−, DAPI+, CEP-8 = 2 (Figure 2D, red arrows); (5) type-E phenotype: circulating tumor microemboli (CTMs) (Figure 2E, orange arrows, 2F).