Background: Reflectance confocal microscopy (RCM) is a noninvasive imaging technique. Currently, RCM is mainly used for the diagnosis of melanoma and nonmelanoma skin cancer including basal cell carcinoma (BCC). Until now, it has not been possible to distinguish between subtypes of BCC using RCM. Objective: To establish the RCM features for subtypes of BCC. Methods: 57 lesions were selected for RCM imaging. Clinical and dermatoscopic pictures were taken and a 3-mm biopsy was obtained. Results: It was demonstrated that tumor nests with peripheral palisading, branch-like structures, fibrotic septa and increase in vascular diameter were characteristic RCM features for nodular and micronodular BCC. The size and shape of the tumor nests allowed further distinction between these BCCs. Solar elastosis and tumor nests connected with the basal cell layer characterize superficial BCC. Conclusion: This study presents RCM features for BCC, which might allow in vivo diagnosis of the nodular, micronodular and superficial subtype of BCC. This could prevent a skin biopsy, resulting in direct proper treatment. Further, RCM allows to evaluate the total lesion, which makes it possible to detect mixed-type BCCs.

Background: In vivo reflectance confocal microscopy (RCM) is a novel, exciting imaging technique. It provides images of cell-and tissue structures and dynamics in situ, in real time, without the need for ex vivo tissue samples. RCM visualizes the superficial part of human skin up to a depth of 250 lm. In psoriasis, an erythematosquamous skin disease, we evaluated well known histological features of stable psoriasis vulgaris (PP) with RCM. RCM images were correlated to morphological and cell biological findings in routine HE and immunohistochemical stained histology with CD3 and antifilaggrin antibodies.Methods: Lesional and nonlesional skin of eight patients with PP were evaluated with RCM, after which 4-mm punch biopsies were taken and cut vertically in two equal parts. One part was processed in the conventional vertical way, the other horizontally (en face) for optimal correlation to RCM images. We evaluated and quantificated nine histopathological features of psoriasis: parakeratosis, epidermal and dermal inflammatory infiltrate, diminished or absent stratum granulosum, epidermal thickening, thinning of the suprapapillary epidermal plate, increased height of the papillary dermis, increase in number of dermal papillae and increase in number and volume of papillary capillaries.Results: Quantification and evaluation of cell biological and histological features of PP with RCM correlated highly to evaluation in HE, CD3 and filaggrin-stained histology.Conclusions: RCM is a novel technique which can be used for real time, cytometric evaluation and quantification of PP features. RCM might be suited equally for cytometric evaluation of other superficial tissues.

Punch biopsy has a high accuracy in single-type BCCs and a considerably lower accuracy in mixed-type BCCs for establishing BCC subtype compared to excision. The presence of an unsuspected aggressive subtype could explain therapy failure of non-surgical treatments like imiquimod or photodynamic therapy.

This study is the first to establish the use of RCM as an effective tool for noninvasive monitoring of UVB phototherapy in patients with psoriasis. Potentially, RCM could be used in many other skin diseases for monitoring therapeutic response on a cellular level in a clinical or research setting.

Reflectance confocal microscopy (RCM) is an imaging tool, which visualizes the epidermal skin layers in vivo with a cellular resolution. Neutrophil accumulation is a characteristic feature in psoriasis and is thought to play a role in the pathophysiology of psoriasis. Until now, imaging of neutrophil accumulation in vivo is not performed. We evaluated the dynamics of neutrophil migration in active psoriatic lesions by non-invasive RCM imaging. Additionally, we evaluated the time phasing and duration of neutrophil trafficking. We performed RCM imaging prior to the start of topical treatment and for seven consecutive days with a 24-h time interval at the Radboud University Medical Center, Nijmegen, the Netherlands. Twelve psoriatic lesions in three patients with a severe exacerbation of psoriasis were included. The four most active lesions were selected in each patient based on the highest degree of redness, induration and expansion in the previous 2 weeks. In all lesions, a cyclic pattern of neutrophil migration was observed, consisting of squirting papillae, transepidermal migration, accumulation in the stratum spinosum, accumulation in the stratum corneum and degeneration of the abscesses. The time interval of a neutrophil-trafficking cycle was 5-7 days and showed a synchronic time phasing. This study is the first to establish the dynamics and time phasing of neutrophil migration in vivo in psoriatic lesions. Previously reported theories were confirmed by these novel in vivo data. RCM might distinguish between active or chronic psoriatic areas, which might contribute to new insights into the pathogenesis of psoriasis.

Summary Background The use of recently introduced biologics targeting specific immune mechanisms has identified crucial steps in the pathogenesis of psoriasis. Studying the dynamics of changes of these target mechanisms in sequential skin biopsies during treatment with biologics may reveal potential biomarkers. Correlation between clinical parameters and the expression of specific genes during treatments may identify markers indicative of treatment response. Objectives This observational open‐label study aimed to provide an overview of important cell biological changes in lesional skin during treatment with adalimumab, and their relationship to clinical improvement. Methods Ten patients with moderate‐to‐severe plaque psoriasis were included and treated with adalimumab for 16 weeks. At baseline, and after 10 days and 16 weeks of treatment clinical scores were assessed and biopsies were taken to examine gene expression at the mRNA and protein level. Results The expression of marker genes for innate immunity, and epidermal differentiation and proliferation was rapidly restored to normal levels, whereas genes of the adaptive immune system showed a delayed decrease. The static and dynamic course of CD1a+ Langerhans cells and Ki67+ nuclei showed a significant strong correlation to the Psoriasis Area and Severity Index score. No correlation between interleukin‐17 expression and clinical scores was found. Conclusions The innate immune system is affected during adalimumab treatment well before the changes in the adaptive immune system become apparent. We may speculate that the addition of a treatment with an early effect on adaptive immunity to adalimumab may result in superior effectiveness compared with monotherapies.

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This is the first study that shows a method for implementation of RCM in dermatology. The strategy and hands on protocol for psoriasis may serve as a model for other dermatological entities and additionally may lead to specialized ready-to-use RCM protocols for clinical dermatological practice.