A comparison of interleukin (IL) 23 expression patterns in patients with chronic plaque psoriasis (CPP; n = 6 using lesional and nonlesional skin), palmoplantar psoriasis (PP; n = 4) and hyperkeratotic hand dermatitis (HHD; n = 4) was conducted. Post hoc analysis showed that there was a significant difference (P < 0.05) in IL-23 staining cells in HHD, PP and lesional psoriasis compared with nonlesional psoriasis. There was no significant difference in the number of such cells between the three disease groups. IL-23 is thus upregulated in HHD and PP and lesional CPP. Targeting IL-23 may be an effective treatment option (possibly via ustekinumab) in these conditions (Lillis, J.V. et al. ...