IL17A mRNA expression by RISH in acral and nonacral samples. (a–c) IL17A composite expression in the entire tissue specimen (a), epidermis (b), and dermis (c) of normal acral skin (n = 9), HPE (n = 12), nonacral eczema (n = 10), PP (n = 8), nonacral psoriasis (n = 9), and MFPP (n = 8). Composite expression was normalized to tissue area in mm2. (d–f) Representative IL17A RISH (red) in PP (d), HPE (e), and normal acral (f) tissue. Middle lines represent medians; upper and lower ends of the boxes represent IQRs; whiskers represent values within 1.5 × IQR. Each point represents an individual case. Bar = 100 μm. HPE, hyperkeratotic palmoplantar eczema; IQR, interquartile range; MFPP, mycosis fungoides palmaris et plantaris; NAE, nonacral eczema; NAP, nonacral psoriasis; NL, normal acral skin; PP, palmoplantar psoriasis; RISH, RNA in situ hybridization.