The in vivo reflectance confocal microscopy (RCM) features of plaque psoriasis were defined and correlations with histopathological findings studied in 36 patients (median age 43.7 years) and 12 normal controls. In > 90% of cases RCM documented hyperkeratosis, parakeratosis, reduced or absent granular layers, papillomatosis and dilated blood vessels. Acanthosis with thicknesses ranging from 75 to 300 mcm and 60 to 90 mcm was observed in psoriatic and normal skin, respectively. The diameter of dermal papillae was enlarged in psoriatic (> 100 mcm) compared to normal skin (> 80 mcm). RCM appears to be a promising tool for noninvasive microscopic diagnosis of plaque psoriasis (Ardigo, M. et al. JEADV 2009, 23(6): ...