Table 1.
RCM features of PP considered in different studies
| RCM criteria | Definition |
|---|---|
| SC thickness | Calculated by z vertical images stack lined from the top of the SC to the stratum granulosum. It is defined as “thickened” when it is more than 20 mm on the face or 40 mm from other localization. |
| Parakeratosis | Presence of nucleated cells in the SC, visualized as bright nuclei in dark corneocytes. Nucleated corneocytes are detected and numbered. |
| Orthokeratosis | Presence of dark anucleated cells with indistinct cellular borders in SC |
| Stratum granulosum thickness | Calculated by z vertical images stack lined from the top of SC to the stratum granulosum |
| Epidermal thickness | Increased epidermal thickness calculated using vertical Viva Stack imaging starting immediately below the SC to the DEJ. It is considered “thickened” when it is more than 60 mm on the face and more than 90 mm on other body localization. |
| Irregular honeycomb pattern | Atypical keratinocytes at the level of the epidermis with absence of polygonal regular keratinocyte shape. |
| Spongiosis | Darker areas at the level of the stratum spinosum, increased interkeratinocyte spaces. |
| Inflammatory cells in epidermis | Presence of bright, round-to-polygonal cells in the epidermis. Microabscesses could be detected as groups of bright polygonal/round cells. |
| Papillomatosis | Presence of increased diameter of DPs (>80 mm), upmigrated DPs (visible at the upper epidermis and corresponding to interpapillary cristae elongation) and decrease of interpapillary spaces. |
| Number of nonrimmed DPs | Presence of dark DPs not surrounded by bright ring of basal keratinocytes. |
| Dilated blood vessels in papillary dermis | Round-to-canalicular dark structures with thin wall, inside DPs at of the level of papillary dermis. |
| Vascularization in the papillary dermis | Blood flow was detected and counted in videos |
| Inflammatory cells in the dermis | Presence of bright, round-to-polygonal cells in the dermis |
Abbreviations: DEJ, dermo–epidermal junction; DP, dermal papilla; PP, plaque psoriasis; RCM, reflectance confocal microscopy; SC, stratum corneum.