FOLH1 and pachyonychia congenita: Nuclear medicine imaging could play a key role in the assessment of PC heterogeneity, particularly in the mCRPC setting, since several radiotracers with different molecular mechanisms are now available (i.e., PSMA ligands, [18F]-choline, [18F]-FACBC, [18F]-FDHT and [18F]-FDG) [39,40].