The evolution of healthy skin to acne lesions: a longitudinal, in vivo evaluation with reflectance confocal microscopy and optical coherence tomography

Abstract

Background Comedogenesis is defined as the process of the development of a new comedo, which is of great importance for the understanding of acne. Objective To evaluate the formation and evolution of acne lesions from clinically unaffected skin of patients with mild–moderate acne to characterize the morphological changes and natural resolution by means of in vivo reflectance confocal microscopy (RCM) and dynamic optical coherence tomography (D‐OCT). Methods Ten patients with mild–moderate acne, not assuming any topical or systemic therapy, comprised between 12 and 30 years of age, were recruited. A target area of 4 × 4 mm of the face, without acne lesions at baseline, was selected. A set of standardized clinical pictures, RCM and D‐OCT images were acquired weekly for 6 weeks and evaluated. Results Seventy full sets of clinical, RCM and D‐OCT images were analysed. The appearance of acne lesion is preceded by an increase of large bright follicles in the area corresponding to infundibular keratinization, followed by increment of inflammation parameter, such as increased of small bright cells upon RCM and vascular network upon D‐OCT, which return to normal after the resolution of acute inflammation. Conclusion Acne skin dynamics is complex and seems characterized by the early increase in the number of dysmorphic pilosebaceous units and the hyperkeratinization of the acroinfundibulum of the pilosebaceous duct prior to the occurrence of inflammatory events around the follicle. The processes of hyperkeratinization and inflammatory phenomena may generate a pathologic vicious cycle, which characterizes acne through progressive worsening and a self‐sustainment mechanism.

Microscopic and functional changes observed with dynamic optical coherence tomography for severe refractory atopic dermatitis treated with dupilumab

“…10,12,15 The clinical application of D-OCT includes assistance in differential diagnosis for selected skin lesions and noninvasive monitoring of treatment effects, especially for inflammatory skin conditions with alterations of blood flow. [16][17][18] A recent study has reported morphologic and vascular characteristic of subclinical AD with an angiographic OCT. 9 Despite there being many studies of the effects of dupilumab on AD disease activity to our knowledge, there are no studies which describe the microscopic and functional changes associated with a systemic therapy.…”

Acne as an altered dermato‐endocrine response problem

“…[77] The following failure of terminal differentiation of follicular corneocytes participates to hyperkeratinization, one of the main factors contributing to acne comedogenesis. [78] Alteration of sebum lipid composition can be involved in impaired barrier function of the infundibular epithelium and comedone generation in acne skin. For example, oleic acid has been reported to regulate human keratinocyte differentiation, as well as to have comedogenic abilities in rabbit auricular skin.…”

“…[ 77 ] The following failure of terminal differentiation of follicular corneocytes participates to hyperkeratinization, one of the main factors contributing to acne comedogenesis. [ 78 ]…”

The Role of Skin Immune System in Acne

“…Manfredini M. et al [ 5 ] assessed the evolution of acne lesions from clinically unchanged skin in mild to moderate acne patients using in vivo reflection confocal microscopy (RCM) and dynamic optical coherence tomography (D-OCT). After analyzing seventy complete sets of clinical pictures comrpising RCM and D-OCT, it was shown that the appearance of an acne lesion is preceded by the growth of large follicles in the area corresponding to funnel keratinization.…”