Reflectance Confocal Microscopy of Dermal Papillae in Healthy Skin: A Histopathology Controlled Study

Previous studies have investigated the density of dermal papillae (DP) in normal skin using reflectance confocal microscopy (RCM), a noninvasive imaging technique that allows a real-time, high-resolution imaging of the skin, although no histological confirmation was provided. The aim of the present study was to compare the RCM evaluation of DP density in healthy skin with horizontal histopathological sections (HHS), a technique that provides a horizontal view of the skin.

Ten adult patients were selected, and a healthy skin area was marked for RCM examination and a subsequent 5-mm punch biopsy that was processed for HHS. Two different blinded operators performed DP counting on RCM and HHS images, respectively.

A total of 10 skin samples were obtained from the lower back. The mean DP density resulting from RCM was 84.27 ± 3.24/mm2, while that from HHS was 84.08 ± 2.74/mm2. Student t test showed no significant differences in DP count between the two techniques (p = 0.89).

The strength of this study is represented by the histological evaluation which has never been previously performed, whose results align with the RCM findings and validate previous data from our group, with negligible differences. We believe that the exact identification of the DP number in normal skin may have practical implications, as several inflammatory skin conditions are characterized by DP changes such as psoriasis, lichen planus, and discoid lupus.