# Psoriasis treated with dithranol: a pilot study on in vivo reflectance confocal microscopy

## TL;DR

This study shows that dithranol treatment rapidly reduces skin abnormalities in psoriasis using a non-invasive imaging technique.

## Contribution

The study introduces in vivo reflectance confocal microscopy as a tool to monitor dithranol's effects on psoriatic skin in real time.

## Key findings

- Dithranol treatment significantly reduced hyperkeratosis, acanthosis, and epidermal thickness within 8 days.
- Dermal changes included reduced dermal papillae and vessel diameters, along with decreased inflammation.
- RCM provided non-invasive, real-time monitoring of treatment effects at the cellular level.

## Abstract

There are only limited histomorphological data on the response of psoriatic skin lesions to topical dithranol. In vivo reflectance confocal microscopy (RCM) in psoriatic skin is highly correlated with histopathological findings and allows non‐invasive monitoring of treatment effects on a cellular level.

Prospective, single‐center pilot study at a university‐based clinic of dermatology between January 1st and August 30th, 2016. Psoriatic lesions of 20 patients receiving dithranol treatment were assessed by RCM at baseline, day 4 and 8 of treatment.

RCM measurements of psoriatic lesions receiving dithranol treatment revealed epidermal histomorphological changes with a strong median reduction of baseline hyperkeratosis by 45.0% (p < 0.001), acanthosis by 38.2% (p < 0.001), and epidermal thickness by 66.5% (p < 0.001) from baseline until day 8. Moreover, semiquantitative measurements of parakeratosis also showed a significant reduction until day 8 (p < 0.001). Correspondingly, RCM revealed dermal histomorphological changes with a decrease in diameter of dermal papillae by 32.1% (p < 0.001), decrease in diameter of papillary vessels by 16.9% (p = 0.002) and a strong semiquantitative reduction of the inflammatory infiltrate (p < 0.001).

Results from our pilot study indicate that topical dithranol treatment of psoriatic lesions may induce a rapid and marked reduction of pathologic epidermal and dermal RCM features.