Reflectance confocal microscopy characteristics of eight cases of pustular eruptions and histopathological correlations

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 skin through reflectance confocal microscopy - Historical background, technical principles, and its correlation with histopathology

Since its first introduction into medical practice, reflectance confocal microscopy (RCM) has been a valuable non-invasive diagnostic tool for the assessment of benign and malignant neoplasms of the skin. It has also been used as an adjunct for diagnosing equivocal cutaneous neoplasms that lack characteristic clinical or dermoscopic features. The use of RCM has led to a decreased number of biopsies of benign lesions. Multiple published studies show a strong correlation between RCM and histopathology thereby creating a bridge between clinical aspects, dermoscopy, and histopathology. Dermatopathologists may potentially play an important role in the interpretation of confocal images, by their ability to correlate histopathologic findings. RCM has also been shown to be an important adjunct to delineating tumoral margins during surgery, as well as for monitoring the non-surgical treatment of skin cancers. Advanced technology with smaller probes, such as the VivaScope 3000, has allowed access to lesions in previously inaccessible anatomic locations. This review explains the technical principles of RCM and describes the most common RCM features of normal skin with their corresponding histological correlation.

Line-field confocal optical coherence tomography: a new tool for non-invasive differential diagnosis of pustular skin disorders

Background

The spectrum of pustular skin disorders (PSD) is large and particularly challenging, including inflammatory, infectious and amicrobial diseases. Moreover, although pustules represent the unifying clinical feature, they can be absent or not fully developed in the early stage of the disease. The line‐field confocal optical coherence tomography (LC‐OCT) is a recently developed imaging technique able to perform a non‐invasive, in vivo, examination of the epidermis and upper dermis, reaching very high image resolution and virtual histology.

Objectives

We aimed to investigate the potentialities of LC‐OCT in the non‐invasive differential diagnosis of a series of 11 PSD with different aetiology, microscopic features, body location and incidence rates.

Materials and Methods

Complete LC‐OCT imaging (i.e. 2D/3D frames, videos) was performed on a total of 19 patients (10 females and 9 males) aged between 35 and 79 years. Images were blindly evaluated and compared with corresponding histopathologic findings.

Results

The LC‐OCT imaging was able to detect with high accuracy the pustule structure including shape, margins, morphology and cellular content, along with peculiar epidermal and adnexal alterations in each condition, including: Acute Generalized Exanthematous Pustulosis, Generalized pustular psoriasis, Generalized pustular figurate erythema, Subcorneal Pustular Dermatosis, Intraepidermal IgA pustulosis, Palmoplantar pustulosis, Palmoplantar pustular psoriasis. Herpetic whitlow, Acrodermatitis continua of Hallopeau, Vesicopustular Sweet syndrome and Vesicopustular Eosinophilic cellulitis, with pustular appearance, were also compared.

Conclusions

The new LC‐OCT can represent a rapid, non‐invasive and painless tool which can help differentiating among PSD of different aetiology and microscopic morphology in clinical mimickers in daily practice.

Diagnosis of Herpes Simplex Virus: Laboratory and Point-of-Care Techniques

Herpes is a widespread viral infection caused by the herpes simplex virus (HSV) that has no permanent cure to date. There are two subtypes, HSV-1 and HSV-2, that are known to cause a variety of symptoms, ranging from acute to chronic. HSV is highly contagious and can be transmitted via any type of physical contact. Additionally, viral shedding can also happen from asymptomatic infections. Thus, early and accurate detection of HSV is needed to prevent the transmission of this infection. Herpes can be diagnosed in two ways, by either detecting the presence of the virus in lesions or the antibodies in the blood. Different detection techniques are available based on both laboratory and point of care (POC) devices. Laboratory techniques include different biochemical assays, microscopy, and nucleic acid amplification. In contrast, POC techniques include microfluidics-based tests that enable on-spot testing. Here, we aim to review the different diagnostic techniques, both laboratory-based and POC, their limits of detection, sensitivity, and specificity, as well as their advantages and disadvantages.

In vivo characterization of pustules in Malassezia Folliculitis by reflectance confocal microscopy and optical coherence tomography. A case series study

BACKGROUND AND OBJECTIVE

Malassezia Folliculitis (MaF) is an inflammatory condition of hair follicles caused by Malassezia yeast. Optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) are imaging technologies enabling in vivo visualization of superficial skin layers. This study explores morphology of pustules in MaF imaged by OCT and RCM.

METHODS

Patients with microscopically verified MaF were included in this case series. Morphology was evaluated qualitatively with RCM and OCT, focusing on shape, border and content of selected pustules.

RESULTS

Nine patients with MaF were included. Clinically, six patients presented monomorphic MaF with multiple superficial pustules, while three patients showed more polymorph MaF appearance. In total 13 pustules were investigated by RCM and OCT. In RCM images, pustules varied from having a well-defined border with homogenous content to ill-defined borders with heterogeneous content. A distinct black halo was occasionally observed around pustules as were dilated vessels. In OCT images, pustules appeared polymorphic, showing both well- and ill-defined structures with oval or irregular shape and more or less homogenous content. Malassezia fungi were not discernible by either RCM or OCT. Specific morphological image features in RCM and OCT did not reflect different clinical manifestations of MaF.

CONCLUSION

RCM and OCT images identify morphological aspects of MaF pustules, and confirm that MaF is a folliculitis with clinical as well as morphological variance.

Dermoscopic and reflectance confocal microscopic presentation of Hailey-Hailey disease: A case series

BACKGROUND/PURPOSE

Hailey-Hailey disease is a rare inherited acantholytic skin disorder characterized by heterogeneous clinical presentation. Its differential diagnosis might be wide, including other genodermatoses, inflammatory, and infectious skin diseases. Although histopathology remains as diagnostic gold standard, noninvasive techniques such as dermoscopy and reflectance confocal microscopy may assist clinical examination. Herein, we aim to further characterize the dermoscopic and reflectance confocal microscopic presentation of Hailey-Hailey disease with histologic correlation.

METHODS

Eight patients with Hailey-Hailey disease were consecutively recruited. All patients were examined using dermoscopy and reflectance confocal microscopy.

RESULTS

In all cases, dermoscopy enabled the visualization of polymorphous vessels, including glomerular and linear-looped vessels, within a pink-whitish background. Reflectance confocal microscopy revealed wide suprabasilar partial acantholysis and clefting, crusts, dilated papillae with tortuous vessels, and inflammatory cells. Dyskeratosis, uplocated papillae, and adnexal sparing were also observed.

CONCLUSION

Although definite diagnosis was obtained by histopathology in all cases, dermoscopy and reflectance confocal microscopy allowed the identification of common features (even in cases with dissimilar clinical presentation) that may support an early diagnosis of Hailey-Hailey disease, and its differentiation from other more frequent skin disorders.

Grover's disease: dermoscopy, reflectance confocal microscopy and histopathological correlation

Grover’s disease is a benign condition of unknown origin characterized clinically by an erythematous papulovesicular eruption and histopathologically by intraepidermal clefting and four different patterns of acantholysis: Darier-like, pemphigus-like, spongiotic, and Hailey-Hailey-like. A case of a 54-year-old female affected by Grover’s disease and showing a Darier-like histopathological pattern is described. Polarized light dermoscopy (PLD) revealed the presence of polygonal, star-like shaped yellowish/brownish areas of various sizes surrounded by a thin whitish halo. Handheld reflectance confocal microscopy (RCM) showed the presence of intraepidermal dark spaces histopathologically corresponding to intraepidermal clefts, roundish, bright cells correlating to acantholytic keratinocytes, target-like cells with a dark center and a highly reflectant halo corresponding to dyskeratotic cells, and epidermal, polygonal, structureless areas reflecting hyperparakeratosis. In conclusion, the use of PLD and RCM combined with clinical presentation, personal/family history, and genetic evaluation may be useful for the non-invasive diagnosis of Darier-like Grover’s disease.

[The role of reflectance confocal microscopy in the diagnosis of secondary syphilis of the vulva and anus: A first case report]

PATIENTS AND METHODS

Herein we report the case of an 18-year-old pregnant patient presenting with plantar and ano-genital lesions of syphilis, pharyngitis, erythematosus and scalynasolabial intertrigo and angular cheilitis.

REFLECTANCE CONFOCAL MICROSCOPY

In vivo reflectance confocal microscopy examination (Vivascope 3000^®; Caliber Inc, Rochester, NY, USA, distributed in France by Mavig, Munich) of ano-genital lesions enabled us to identify hyper-reflective elongated rods in the papillary dermis suggesting spirochetes. The diagnosis was confirmed by TPHA and VDRL as well as immunohistological examination.

COMMENTS

We identified for the first time rod shaped structures in ano-genital lesions of secondary syphilis, regularly alternating hyper-reflective and non-reflective areas corresponding to helix-shaped treponemes visualized by darkfield microscopy, which may not be confused with other cell structures.

Reflectance confocal microscopy in the diagnosis of vesicobullous disorders: case series with pathologic and cytologic correlation and literature review

BACKGROUND

Vesicobullous disorders are characterized by intraepidermal or subepidermal blistering resulting from different pathogenetic mechanisms. The diagnosis is generally based on clinical examination and semi-invasive/invasive procedures such as cytology and histopathology. In vivo reflectance confocal microscopy (RCM) is a non-invasive technique for real-time, en face imaging of the epidermis and upper dermis with high resolution close to conventional histopathology.

PURPOSE

To evaluate RCM features of different vesicobullous diseases and correlate with cytologic and histopathologic examination.

METHODS

Ten patients (6M/4F, age range: 9-81 years) affected by blistering diseases, such as herpes simplex, herpes zoster, Kaposi's varicelliform eruption, pemphigus vulgaris, Hailey-Hailey disease, bullous pemphigoid, and porphyria cutanea tarda were evaluated using a handheld RCM device.

RESULTS

In our study, a clear correlation between RCM and Tzanck's test and/or histopathology was observed. RCM allowed in all cases an easy identification of the blister spaces and of the split levels, and in some cases specific features were detected, such as giant keratinocytes in herpes infections and acantholytic cells in pemphigus vulgaris and Hailey-Hailey disease.

CONCLUSION

Reflectance confocal microscopy may support the clinical diagnosis of vesicobullous disorders and indicate to the physician the appropriate patient management and/or the need for further investigation.

A four-phase strategy for the implementation of reflectance confocal microscopy in dermatology

BACKGROUND

Reflectance confocal microscopy (RCM) is gradually implemented in dermatology. Strategies for further implementation and practical 'hands on' guidelines are lacking.

OBJECTIVE

The primary outcome was to conduct a general strategy for further implementation of RCM. The secondary outcome was the diagnosis of psoriasis and differentiation of stable from unstable psoriatic plaques by means of the 'hands on' protocol, derived from the strategy.

METHODS

We used a four-phased model; an exploring phase, a systematic literature search, a clinical approach and, finally, an integration phase to develop a clinical guideline for RCM in psoriasis. Receiver operating characteristic curve statistics was applied to define the accuracy for the diagnosis of unstable psoriasis.

RESULTS

A general strategy for further implementation of RCM and practical approach was developed to examine psoriasis by RCM and to distinguish stable from unstable psoriasis. Unstable psoriasis was diagnosed by epidermal inflammatory cell counts with a sensitivity and specificity of 91.7% and 98.3%, respectively, and with an accuracy of 0.92 (area under the curve). In addition, a monitoring model was proposed.

CONCLUSION

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.

Application of leukotriene B4 and reflectance confocal microscopy as a noninvasive in vivo model to study the dynamics of skin inflammation

BACKGROUND

Application of leukotriene B4 (LTB4) is an established in vivo model that locally induces skin inflammation. Currently in this model, a biopsy is inevitable. In vivo reflectance confocal microscopy (RCM), a noninvasive imaging technique, could overcome this limitation. To find out to what extent RCM may be an in vivo investigative and diagnostic tool in neutrophilic conditions, we studied the dynamics of polymorphonuclear leukocytes (PMN) migration from dermis to stratum corneum using an established LTB4 model.

METHODS

Leukotriene B4 was topically applied on the skin of the lower back of seven volunteers. The skin sites were evaluated by RCM for three consecutive days with a 24 h time interval. For histological correlation, 3-mm punch biopsies were obtained. The tissue sections were hematoxylin-eosin and immunohistochemical stained. Minimal and average epidermal thickness was measured.

RESULTS

Reflectance confocal microscopy imaging showed highly reflective ill-defined particles with a granular content throughout the epidermis 24 h after application of LTB4. Over time, the appearance of these cells changed throughout the epidermis. Epidermal thickness increased over time, and the measurements based on the RCM images corresponded very well with the histological images.

CONCLUSIONS

Reflectance confocal microscopy was able to visualize PMN migration, accumulation, and degeneration over time in the used LTB4 model. The noninvasive character and the possibility to obtain multiple in vivo images from the same location over time make that RCM in combination with this model a useful tool to study the dynamics and function of PMN in inflammatory processes in the skin.