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

Die Bedeutung von Mikrokomedonen bei der Akne: Von der Beschreibung bis zum Behandlungsansatz?: The role of microcomedones in acne: Moving from a description to treatment target?

Ein wichtiger Faktor in der Pathogenese der Akne vulgaris ist die duktale Hyperproliferation der Talgdrüsen. Diese beginnt mit der Bildung unsichtbarer Mikrokomedonen und führt im weiteren Verlauf zur Ausbildung sowohl entzündlicher als auch nicht‐entzündlicher klinischer Läsionen. Die Mikrokomedonen stehen am Anfang der zyklischen Entwicklung einer Akne, die als Komedogenese bezeichnet wird. Mikrokomedonen können mithilfe von Cyanoacrylat‐Hautablösungen, Elektronenmikroskopie, konfokaler Reflexionsmikroskopie und anderen Techniken nachgewiesen werden. Es wird angenommen, dass die Dichte und Größe von Mikrokomedonen positiv mit dem Schweregrad der Akne korreliert. Ziel dieser Übersichtsarbeit ist es, die Ursachen der Akne zusammenzufassen und darauf hinzuweisen, dass die Behandlung von Mikrokomedonen zumindest teilweise Akneläsionen beseitigen und Rückfälle verhindern könnte.

The role of microcomedones in acne: Moving from a description to treatment target?

A major factor in the pathogenesis of acne is ductal hyperproliferation in the pilosebaceous glands. This takes the form of invisible microcomedones and leads to the subsequent formation of both inflammatory and non-inflammatory clinical lesions. Microcomedones are the initial stage in the cyclical development of acne, so called comedogenesis. Microcomedones can be detected using cyanoacrylate skin surface stripping, electron microscopy, reflection confocal microscopy and other techniques. It has been proposed that the density and the size of microcomedones are positively correlated with acne severity. Thus, the purpose of this review is to summarize the root causes of acne, and suggest that treatment of microcomedones could, at least in part, resolve acne lesions and prevent relapse.

The role of in vivo reflectance confocal microscopy for the management of acne: A systematic review

Acne diagnosis, severity assessment and treatment follow-up rely primarily on clinical examination. In vivo reflectance confocal microscopy (RCM) provides non-invasively, real-time images of skin lesions with a level of detail close to histopathology. This systematic literature review aims to provide an overview of RCM utility in acne and a summary of specific features with clinical application that may increase objectivity in evaluating this condition. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for reporting our results. We systematically searched three databases: PubMed, Clarivate and Google Scholar (January 2022). All included studies used RCM to investigate acne in human patients and reported the investigated skin area and type (acne lesions or clinically uninvolved skin), the substance used in the case of treatment. Our search identified 2184 records in the three databases investigated. After duplicate removal, 1608 records were screened, 35 were selected for full-text assessment, and 14 were included in this review. We used the QUADAS-2 tool to evaluate the risk of bias and applicability concerns. RCM was selected as the index test and clinical examination as the reference standard. The total number of patients from all studies was 291, with 216 acne patients and 60 healthy participants aged between 13 and 45 years. The 14 considered studies analysed 456 follicles from healthy participants, 1445 follicles from uninvolved skin in acne patients and 1472 acne lesions. Consistent RCM findings concerning follicles of acne patients reported across studies were increased follicular infundibulum size, thick, bright border, intrafollicular content and inflammation. Our analysis indicates that RCM is a promising tool for acne evaluation. Nevertheless, standardization, a unified terminology, consistent research methods and unitary reporting of RCM findings are necessary. PROSPERO registration number CRD42021266547.

A preliminary study on the evaluation of photodynamic diagnosis for acne inflammatory skin lesions

OBJECTIVE

This study aimed to observe the fluorescence characteristics of acne inflammatory skin lesions in 5-aminolevulinic acid-based photodynamic diagnosis (ALA-PDD), and discuss the viability of using ALA-PDD to evaluate acne inflammatory skin lesions and explore the advantages of predicting subclinical skin lesions.

METHODS

The OBSERV facial skin detector collected photographs of 20 patients before and after optical intra-tissue fiber irradiation photodynamic therapy (OFI-ALA-PDT) in both ALA-PDD and white light patterns. The patients were treated once a week for four consecutive weeks in order to analyze the correlation between the two patterns in recognizing inflammatory skin lesions.

RESULTS

Before and after treatment, there was no significant difference between the two patterns for recognizing acne inflammatory skin lesions (p > 0.05). Both patterns demonstrated a strong correlation (r > 0.90) for the recognition of various types of inflammatory skin lesions at different treatment stages.

CONCLUSION

ALA-PDD is a feasible method for evaluating acne inflammatory lesions, guiding treatment and judging efficacy. It has advantages in predicting subclinical skin lesions and deserves further study.

The assessment of moderate acne vulgaris face skin using blood perfusion and hyperspectral imaging-A pilot study

BACKGROUND

Microcirculation is the flow of blood through the smallest vessels in the circulatory system. Capillaries respond to various pathologies much earlier than arteries and veins, the changes which indicate that the disease is already developing. Careful monitoring of the functioning of the capillary system often allows the detection of in vivo disorders at an early stage.

AIMS

The aim of the study was to evaluate the microcirculation within acne lesions. A noninvasive method of semi-quantitative blood perfusion measurement based on laser speckle contrast analysis (LASCA) and a quantitative assessment of the acne severity using the hyperspectral imaging method supported by image analysis and processing methods were used.

PATIENTS/METHOD

The acne lesion perfusion was compared to the healthy skin perfusion of the control group. The reflectance in the range from 400 to 1000 nm was also compared for acne lesions and healthy skin. A dedicated version of the algorithm based on the gray-level co-occurrence matrix was used to compare differences between acne lesions and healthy skin.

RESULTS

Blood perfusion in acne lesions is on average 117% higher than in healthy skin. The reflectance of acne lesions was lower in the range of 400-600 nm compared to the healthy skin. A statistically significant decrease in the reflectance of acne lesions was demonstrated for wavelengths: 434, 549, and 588 nm.

CONCLUSIONS

Increased blood perfusion in acne lesions compared to healthy skin suggests increased chemotaxis of inflammatory cells and wound healing. Decrease points in skin reflectance resemble the absorption peaks for hemoglobin and coproporphyrin III produced by Cutibacterium acnes. Thus, the proposed methods may serve not only for the early detection of acne lesions, before they manifest themselves clinically for the naked eye, but may also be a tool for quantifying the effectiveness of acne treatment.

Insulin and the sebaceous gland function

Insulin affects metabolic processes in different organs, including the skin. The sebaceous gland (SG) is an important appendage in the skin, which responds to insulin-mediated signals, either directly or through the insulin growth factor 1 (IGF-1) axis. Insulin cues are differently translated into the activation of metabolic processes depending on several factors, including glucose levels, receptor sensitivity, and sebocyte differentiation. The effects of diet on both the physiological function and pathological conditions of the SG have been linked to pathways activated by insulin and IGF-1. Experimental evidence and theoretical speculations support the association of insulin resistance with acne vulgaris, which is a major disorder of the SG. In this review, we examined the effects of insulin on the SG function and their implications in the pathogenesis of acne.

Characterization of Acne-Prone Skin with Reflectance Confocal Microscopy and Optical Coherence Tomography and Modifications Induced by Topical Treatment and Probiotic Supplementation

The evaluation of acne-prone skin and absent-to-mild acne is difficult because this condition is not associated with a clinically definable situation. Previous studies showed that apparently healthy skin in patients with previous episodes of acne shows microcomedos and infundibular hyperkeratosis upon reflectance confocal microscopy (RCM) evaluation. Our aim was to characterize the subclinical and microscopic characteristics of acne-prone skin by means of RCM and dynamic optical coherence tomography (D-OCT) and evaluate microscopic changes induced by treatment. A group of 20 patients received a daily combined treatment over a period of 3 months, consisting of probiotic supplementation with three strains of 10⁹ colony-forming units of Lactobacillus (Lactobacillus reuteri, Lactobacillus casei subsp. rhamnosus, Lactobacillus plantarum) and a combined topical product of azelaic and hydroxypinacolone retinoate (HPR). Clinical evaluations and non-invasive imaging acquisitions using VISIA^® System, RCM, and D-OCT were performed at baseline, and after 4 and 12 weeks. The total number of clinically evident non-inflammatory lesions decreased during treatment from 11.5 to 7.3 (p < 0.05). There was also an evident reduction in microscopic acne features at RCM and D-OCT, such as the number of small bright follicles, large bright follicles and vascular threshold density at 300 μm and 500 μm depths. The types and extent of microscopic alterations in acne-prone skin patients may not be evident by clinical scores. Patients with low investigator global assessment (IGA) grades are a heterogeneous population, characterized by different microscopic skin features. Acne-prone skin is susceptible to treatment, and RCM and D-OCT imaging are sensitive tools to objectively monitor subclinical skin changes.

Confocal microscopy and optical coherence tomography of inflammatory skin diseases in hairs and pilosebaceous units: A systematic review

Common skin disorders such as acne vulgaris, rosacea and folliculitis are bothersome prevalent inflammatory diseases of hair follicles that can easily be investigated bedside using optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) with micrometre resolution, opening a novel era for high-resolution hair follicle diagnostics and quantitative treatment evaluation. EMBASE, PubMed and Web of Science were searched until 5 January 2023 to identify all studies imaging hair follicle characteristics by RCM and OCT for diagnosis and monitoring of treatment in hair follicle-based skin disorders. This study followed PRISMA guidelines. After inclusion of articles, methodological quality was assessed using the QUADAS-2 critical appraisal checklist. Thirty-nine in vivo studies (33 RCM and 12 OCT studies) were included. The studies focused on acne vulgaris, rosacea, alopecia areata, hidradenitis suppurativa, folliculitis, folliculitis decalvans, lichen planopilaris, discoid lupus erythemasus, frontal fibrosing alopecia and keratosis pilaris. Inter- and perifollicular morphology including number of demodex mites, hyperkeratinization, inflammation and vascular morphology could be assessed by RCM and OCT in all included skin disorders. Methodological study quality was low, and interstudy outcome variability was high. Quality assessment showed high or unclear risk of bias in 36 studies. Both RCM and OCT visualize quantitative features as size, shape, content and abnormalities of hair follicles, and have potential to support clinical diagnosis and evaluate treatment effects. However, larger studies with better methodological quality are needed to implement RCM and OCT directly into clinical practice.

The influence of cosmetics dedicated to oily and acne-prone skin on skin parameters

INTRODUCTION

Patient compliance with care recommendations is closely related to the role of cosmetics in delaying or preventing the side effects of medications used to treat acne.

METHODS

A total of 33 volunteers with symptoms of acne vulgaris were qualified for the study. The skin parameters were measured before the experiment, after the 4 and at the 8 weeks of use. The measurements were subject to moisturizing the skin and secretion of sebum and skin color. A skin acoustic parameters using high-frequency ultrasound (33 MHz) was also performed. The recorded images were used to determine the epidermal entrance echo thickness and echo density of dermis.

RESULTS

The results show a change in the value of skin parameters during the 8-week application of a specific skin care procedure. The secretion of sebum did not change significantly, there was a decrease in hydration, and the level of melanin and hemoglobin remained at the same level. The thickness of the epidermis entrance echo in the ultrasound image was thinned.

CONCLUSION

For many mild/moderate acne patients, cosmetics proven to be effective and well tested in clinical trials can offer a real benefit in reducing both inflammation, sebum production, melanin, and irritation, but should also be moisturizing.

Dermoscopy, Reflectance Confocal Microscopy and Optical Coherence Tomography Features of Acne: A Systematic Review

Noninvasive imaging techniques have recently outlined precise microscopic features of acne elementary lesions and accurate quantifications for disease severity staging and therapeutical efficacy follow-up. The aim of this review is to systematically describe current applications of dermoscopy, reflectance confocal microscopy (RCM), and optical coherence tomography (OCT) in acne vulgaris assessment and management. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We included studies conducted on human subjects with elementary lesions of acne vulgaris, reporting assessment of the lesions with dermoscopy, RCM, and/or OCT. At present there are few large studies regarding acne and noninvasive imaging techniques, representing the main limitation of this review. Clinical examination represents the first line in acne diagnosis and treatment. However, dermoscopy, RCM, and OCT are further tools that can improve acne classification, monitoring of treatment, and pathophysiologic characterization. In the near future, dermoscopy, RCM, and OCT could become routinely used for the evaluation of acne vulgaris to provide a deeper knowledge of the disease and to guide the clinician in the prescription of tailored treatment protocols based on each patient’s characteristics.

The Role of Skin Immune System in Acne

Acne vulgaris is a skin disease that often occurs in adolescence and in young adulthood. The main pathogenic factors are hyperkeratinization, obstruction of sebaceous glands, stimulation of sebaceous gland secretion by androgens, and bacterial colonization of sebaceous units by Cutibacterium acnes, which promotes inflammation. Little is known about the role of skin immune cells in the development of acne lesions. The aim of the study was to try to understand the role of skin immune cells in the course of acne. Recent studies have shown that there are at least four major pathways by which Cutibacterium acnes interacts with the innate immune system to induce inflammation: through TLRs, activating inflammasomes, inducing the production of matrix metalloproteinases (MMPs), and stimulating antimicrobial peptide (AMP) activity. Cells of adaptive immune response, mainly Th1 and Th17 lymphocytes, also play an important role in the pathogenesis of acne. It is worth emphasizing that understanding the role of the skin’s immune cells in the pathogenesis of acne may, in the future, contribute to the application of modern therapeutic strategies that would avoid addiction to antibiotics, which would alleviate the spectrum of resistance that is now evident and a current threat.

Hidradenitis Suppurativa: morphologic and vascular study of nodular inflammatory lesions by means of optical coherence tomography

BACKGROUND

Hidradenitis Suppurativa (HS) is an inflammatory disease characterized by a recurrent-remission trend and clinical lesions that range from asymptomatic to inflamed, deep-seated nodules with scarring and suppuration.

OBJECTIVE

To identify morphologic and vascular features of HS nodules by means of dynamic optical coherence tomography (D-OCT) and to define if they are correlated to patient endotype and risk of disease progression.

METHODS

A set of standardized clinical pictures and D-OCT images were acquired from 57 inflammatory nodules of 40 patients affected by HS. A set of 20 clinical and D-OCT images were acquired from 20 healthy volunteers as a control group. The comparison of D-OCT features among HS and control group was analyzed. The correlation between HS patient endotype and D-OCT features of the lesions was calculated.

RESULTS

D-OCT enabled to identify vascular and morphological aspects characterizing HS nodular inflammatory lesions. In addition, several D-OCT features were significantly different among distinct disease endotypes.

CONCLUSION

The characterization of HS nodular inflammatory lesions through D-OCT, corresponding to blood vessel dilation and inflammatory associated hyper-vascularization, may have important clinical consequences in the assessment of HS risk of progression, therapeutic decisions and treatment efficacy monitoring.

Optical coherence tomography

During the past decade, noninvasive imaging has emerged as a valuable tool in clinical dermatology and dermatologic research. Optical coherence tomography (OCT) is one such type of noninvasive imaging. OCT uses the principle of interferometry to produce real-time images. A low-power diode laser shines infrared light onto tissues, which reflects back to an optical fiber interferometer. Using time delay and the backscattered light intensity, a two-dimensional image akin to an ultrasound is rendered. We review the history, types, and modalities of OCT, plus the many applications of frequency domain, high definition, and dynamic OCT in practice, including its utility in diagnosis, monitoring, and grading disease severity in a variety of cutaneous conditions.

[Advances in optical coherence tomography]

Optical coherence tomography (OCT) has been able to establish itself in recent years not only in academic-scientific, but also in everyday dermatological practice. Its focus lies on epithelial tumors of the skin, which can be diagnosed intuitively and within a few seconds. Thus, basal cell carcinomas, actinic keratoses, and different stages of field cancerization can be diagnosed and monitored for response to therapy or possible recurrence. This often helps to avoid invasive sample extraction. Recently, the field of OCT and its latest advancement, dynamic OCT (D-OCT), has been expanded to include non-oncologic dermatological diseases. This encompasses inflammatory dermatoses and the analysis of physiological skin parameters such as hydration. Thanks to automated vascular imaging and the measurement of objective parameters such as epidermal thickness, blood flow at depth, optical attenuation coefficient, and skin roughness, more and more characteristics of the skin can be studied in a noninvasive and standardized way. New potential areas of application are eczema, contact allergic dermatitis, psoriasis, rosacea, telangiectasia, acute and chronic wounds, melasma and nevus flammeus but also melanocytic lesions.

Clinical Applications of In Vivo and Ex Vivo Confocal Microscopy

Confocal laser scanning microscopy (CLSM) has been introduced in clinical settings as a tool enabling a quasi-histologic view of a given tissue, without performing a biopsy. It has been applied to many fields of medicine mainly to the skin and to the analysis of skin cancers for both in vivo and ex vivo CLSM. In vivo CLSM involves reflectance mode, which is based on refractive index of cell structures serving as endogenous chromophores, reaching a depth of exploration of 200 μm. It has been proven to increase the diagnostic accuracy of skin cancers, both melanoma and non-melanoma. While histopathologic examination is the gold standard for diagnosis, in vivo CLSM alone and in addition to dermoscopy, contributes to the reduction of the number of excised lesions to exclude a melanoma, and to improve margin recognition in lentigo maligna, enabling tissue sparing for excisions. Ex vivo CLSM can be performed in reflectance and fluorescent mode. Fluorescence confocal microscopy is applied for “real-time” pathological examination of freshly excised specimens for diagnostic purposes and for the evaluation of margin clearance after excision in Mohs surgery. Further prospective interventional studies using CLSM might contribute to increase the knowledge about its application, reproducing real-life settings.

Creatine Phosphokinase Values during Low Starting Dose Isotretinoin Therapy

BACKGROUND

The value of creatine phosphokinase (CPK) monitoring during isotretinoin therapy is still a matter of debate because of the rarity of muscular and kidney damage in this setting. The aim of the study was to investigate the incidence of CPK elevation during a low starting dose isotretinoin regimen and to discuss the clinical approach to patients with increased CPK.

METHODS

We reviewed the records of the acne patients from 2015 to 2018 at the University of Ferrara and at the University of Modena and Reggio Emilia. Routine clinical and laboratory follow-up was analyzed.

RESULTS

The records of 328 patients were included in the study. Abnormal CPK levels were observed in 5.5% of cases. Revised Leeds acne scores and visual assessment scale (VAS) measurements decreased significantly after isotretinoin therapy.

DISCUSSION

The adoption of the low starting dose isotretinoin regimen is associated with low incidence of CPK elevation. The finding of CPK over the conventional value of 5 times above the limit was rarely observed and was never associated with kidney damage. Therefore, it should be interpreted as a relatively benign phenomenon that does not require the interruption of isotretinoin therapy and that should be managed mainly through the reassurance of the patient.