In vivo imaging of Sarcoptes scabiei infestation using line‐field confocal optical coherence tomography

Line-Field Confocal Optical Coherence Tomography: A New Skin Imaging Technique Reproducing a "Virtual Biopsy" with Evolving Clinical Applications in Dermatology

BACKGROUND

Line-field confocal optical coherence tomography is a novel technology able to reproduce a "virtual biopsy" of the skin. The aim of this review is to explore the application of line-field confocal optical coherence tomography (LC-OCT) in various skin diseases, covering skin cancers, inflammatory and infectious skin diseases, genetic diseases, cosmetic procedures, and less common disorders.

METHODS

Study selection was conducted based on LC-OCT and using pertinent MeSh terms, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines from inception to March 2024; to evaluate the quality and risk of bias of studies, Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used.

RESULTS

the search retrieved 154 papers according to the selection criteria; after removing publications by one or more of the exclusion criteria, a total of 96 studies were found to be suitable for the analysis.

CONCLUSIONS

Increasing evidence supports the use of LC-OCT as an adjunctive diagnostic tool for the in vivo diagnosis of a variety of skin tumors. As this device can be considered a "bridge" between dermoscopy and histopathology, widening applications in numerous fields of clinical dermatology, including inflammatory skin disease treatment, presurgical mapping, cosmetic procedures, and monitoring of non-invasive therapies, have been explored.

Line-field confocal optical coherence tomography of eyelid margin growths: A case series

BACKGROUND

The clinical differential diagnosis of lesions arising on the eyelid margin may be challenging and an unneeded surgical approach may have serious functional and aesthetic consequences. Nonetheless, early recognition and treatment of malignant tumors of the eyelid margin is mandatory. Line-field confocal optical coherence tomography (LC-OCT) is a novel tool for the in vivo, real-time skin imaging.

OBJECTIVES

The aim of the study was to identify and analyze the LC-OCT features of a series of eyelid margin growths and to correlate these features with the histopathological findings.

METHODS

Patients with eyelid margin growths who were scheduled for lesion excision underwent LC-OCT examination. Inclusion criteria were a challenging clinical aspect of the lesions and a clinical history of recent onset (up to 12 months). In all cases, the histopathological examination of the excised lesions was performed for the final diagnosis.

RESULTS

A total of 31 lesions located on the upper (13 cases) or lower (18 cases) eyelid margin from 28 consecutive patients (male = 15, female = 13; mean age: 64.7 years, range: 44-87 years) were evaluated and excised. The histopathologic diagnoses were nodular basal cell carcinoma (BCC) (nine cases), squamous cell carcinoma (SCC) (three cases), compound nevus (four cases), dermal nevus (two cases), seborrheic keratosis (four cases), pyogenic granuloma (one case), trichilemmal cyst (three cases), and hidrocystoma (five cases). LC-OCT allowed the in vivo recognition of the main microscopic features of the examined lesions.

CONCLUSIONS

LC-OCT represents a promising tool for the evaluation of eyelid margin lesions. Advantages of non-invasive diagnosis particularly relevant in such a sensitive region include a more correct planning of the treatment and, in case of surgery, the most appropriate surgical approach and, importantly, a correct timing of intervention.

Diagnostic Accuracy of Line-Field Confocal Optical Coherence Tomography for the Diagnosis of Skin Carcinomas

Line-field confocal optical coherence tomography (LC-OCT) is a new, noninvasive imaging technique for the diagnosis of skin cancers. A total of 243 benign (54%) and malignant (46%) skin lesions were consecutively enrolled from 27 August 2020, to 6 October 2021 at the Dermatology Department of the University Hospital of Siena, Italy. Dermoscopic- and LC-OCT-based diagnoses were given by an expert dermatologist and compared with the ground truth. Considering all types of malignant skin tumours (79 basal cell carcinomas (BCCs), 22 squamous cell carcinomas, and 10 melanomas), a statistically significant increase (p = 0.013) in specificity was observed from dermoscopy (0.73, CI 0.64-0.81) to LC-OCT (0.87, CI 0.79-0.93) while sensitivity was the same with the two imaging techniques (0.95 CI 0.89-0.98 for dermoscopy and 0.95 CI 0.90-0.99 for LC-OCT). The increase in specificity was mainly driven by the ability of LC-OCT to differentiate BCCs from other diagnoses. In conclusion, our real-life study showed that LC-OCT can play an important role in helping the noninvasive diagnosis of malignant skin neoplasms and especially of BCCs. LC-OCT could be positioned after the dermoscopic examination, to spare useless biopsy of benign lesions without decreasing sensitivity.

Dermoscopic features of children scabies

Scabies is a common skin disorder, caused by the ectoparasite Sarcoptes scabiei. The scabies mites burrow is highly diagnostic but illegible by the naked eye, because it is tiny and may completely be obscured by scratch and crust. The classic technique is opening the end of an intact mite burrow with a sharp instrument and inspecting its contents in the light microscope under loupe vision. Dermatoscope is a new method to diagnose scabies, with the advantages of non-invasive and more sensitive. This study verified the characteristic manifestations of scabies under dermoscopy. Under the closer examination of the curvilinear scaly burrow, the scabies mite itself may be seen as a dark equilateral triangular structure, which is often referred to as a "jet with contrail." Besides, this study found that the positive detection rate of microscopic characteristic manifestations under the dermoscopy ordered by the external genitals, the finger seams and the trunk, which were statistically different (P-value < 0.05). Of note, this is the first study to explore the regional distribution of the characteristic dermoscopic manifestations of scabies. We are the first to propose to focus on examining the external genitalia and finger seams with dermoscopy.

Line-field confocal optical coherence tomography of psoriasis, eczema and lichen planus: a case series with histopathological correlation

BACKGROUND

Line-field confocal optical coherence tomography (LC-OCT) is a novel, non-invasive technique that provides in vivo, high-resolution images in both vertical and horizontal sections.

OBJECTIVES

The aim of the study was to evaluate LC-OCT imaging in some inflammatory disorders and to correlate the resulting features with histopathology.

METHODS

The retrospective study included patients with histopathological confirmed diagnosis of plaque psoriasis, atopic eczema and lichen planus, who were imaged with LC-OCT before the biopsy. LC-OCT was performed with the commercially available LC-OCT device.

RESULTS

A total of 15 adult patients with histopathologically proven plaque psoriasis (N: 5), atopic eczema (N: 5) and lichen planus (N: 5) were included. In all cases, LC-OCT allowed the in vivo recognition of the main microscopic features of the examined inflammatory skin disease, with a strong correlation with histopathology.

CONCLUSIONS

Although future studies on larger series of patients are necessary, LC-OCT, based on these preliminary findings, may represent a promising tool in inflammatory skin disorders with potential applications including enhanced diagnosis, biopsy guidance, follow-up and treatment monitoring.

Line-field confocal optical coherence tomography as a tool for three-dimensional in vivo quantification of healthy epidermis: A pilot study

Epidermal three-dimensional (3D) topography/quantification has not been completely characterized yet. The recently developed line-field confocal optical coherence tomography (LC-OCT) provides real-time, high-resolution, in-vivo 3D imaging of the skin. This pilot study aimed at quantifying epidermal metrics (epidermal thicknesses, dermal-epidermal junction [DEJ] undulation and keratinocyte number/shape/size) using 3D LC-OCT. For each study participant (8 female, skin-type-II, younger/older volunteers), seven body sites were imaged with LC-OCT. Epidermal metrics were calculated by segmentations and measurements assisted by artificial intelligence (AI) when appropriate. Thicknesses of epidermis/SC, DEJ undulation and keratinocyte nuclei volume varied across body sites. Evidence of keratinocyte maturation was observed in vivo: keratinocyte nuclei being small/spherical near the DEJ and flatter/elliptical near the skin surface. Skin microanatomy can be quantified by combining LC-OCT and AI. This technology could be highly relevant to understand aging processes and conditions linked to epidermal disorders. Future clinical/research applications are to be expected in this scenario.

[Confocal line-field OCT]

Optical coherence tomography (OCT) and confocal laser microscopy (CLSM) are established non-invasive methods in clinical dermatological routine diagnosis. Whereas CLSM is especially useful to distinguish between nevi and melanoma, OCT is suitable for the diagnosis and differentiation of non-melanoma skin cancer. Line-field confocal optical coherence tomography (LC-OCT) is a new innovative device, which has better cellular resolution than OCT and a higher penetration depth than CLSM. Similar to CLSM, LC-OCT also allows 3D images in real time to be taken. Therefore LC-OCT is very useful for the examination of skin lesions of all kinds, since it unites the features of CLSM and OCT.

Line-Field Confocal Optical Coherence Tomography May Enhance Monitoring of Superficial Basal Cell Carcinoma Treated with Imiquimod 5% Cream: A Pilot Study

Line-field confocal optical coherence tomography (LC-OCT) is a novel, non-invasive technique for real-time skin imaging. Imiquimod (IQ) 5% cream is an immune response modifier currently approved for the treatment of small, superficial basal cell carcinoma (BCC). The aim of this study was to investigate if LC-OCT may be useful to enhance the treatment monitoring of BCC. Twenty superficial BCCs from 12 patients were treated with IQ 5% cream once daily, five days a week, for six weeks. Clinical and LC-OCT evaluations were performed at baseline and 4 weeks after the end of treatment. At the end of the study, 13 lesions showed a complete clinical and LC-OCT response, 4 lesions a partial clinical and LC-OCT response, and 3 lesions a complete clinical response but residual tumoral signs at LC-OCT. Our pilot study suggests that LC-OCT may represent a promising tool able to enhance the evaluation of the treatment response of BCCs to non-invasive treatments. In our case series, its use highlighted, through a detailed, fast, and complete examination of the treated area, three cases of residual BCC that otherwise would have gone undetected at clinical examination. Future studies on larger series of patients treated with different modalities and with a longer follow-up are advisable.

Line-field confocal optical coherence tomography of xanthogranuloma: Correlation with vertical and horizontal histopathology

Line‐field confocal optical coherence tomography (LC‐OCT) is a new noninvasive technique for a real‐time, vertical, and horizontal imaging of the skin at cellular resolution. A 47‐year‐old female presented with a 6‐month history of an asymptomatic yellowish papule. LC‐OCT evaluation was able to show the diagnostic microscopic features of xanthogranuloma and showed an excellent correlation with vertical and horizontal histopathological sections by revealing enlarged dermal papillae containing multiple, bright roundish giant cells, corresponding to foamy histiocytes, and giant cells characterized by a dark center surrounded by a highly hyper‐refractile peripheral ring, corresponding to Touton cells. LC‐OCT may represent a valid, noninvasive alternative to histopathological examination in clinically atypical cases of xanthogranuloma.

Line-field optical coherence tomography: In vivo diagnosis of basal cell carcinoma subtypes compared to histopathology

BACKGROUND

Basal cell carcinoma (BCC) is the most common skin cancer in the general population. Treatments vary from Mohs surgery to topical therapy, depending on the subtype. Dermoscopy, reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) have gained a foothold in daily clinical practice to optimize diagnosis and subtype-oriented treatment. The new device Line-field confocal OCT (LC-OCT) allows imaging at high resolution and depth but its use is not yet been investigated in larger studies.

OBJECTIVES

To evaluate the main LC-OCT criteria for the diagnosis and subtyping of BCC in comparison to histopathology, OCT and RCM.

METHODS

Fifty-two histopathologically confirmed BCCs were evaluated for imaging criteria. Their frequency, predictive values and ROC curves were calculated. A multinominal regression with stepwise variables selection to distinguish BCC subtypes was performed.

RESULTS

Nodular BCCs were mainly characterized by atypical keratinocytes, altered DEJ, tumour nests in the dermis, dark clefting, prominent vascularisation and white hyperreflective stroma. Superficial BCCs showed a thickening of the epidermis due to a series of tumour lobules with clear connection to the DEJ (string of pearls pattern). Infiltrative BCCs were characterized by elongated hyporeflective tumour strands, surrounded by bright collagen (shoal of fish). The overall BCC subtype agreement between LC-OCT and conventional histology was 90.4 % (95% CI: 79.0, 96.8).

CONCLUSION

LC-OCT allows the non-invasive, real time identification of BCCs and their subtypes in vertical, horizontal and 3D mode compared to histology, RCM and OCT. Further larger studies are needed to better explore the clinical applications of this promising device.

[Noninvasive diagnostic imaging in pediatric skin lesions]

Optical coherence tomography (OCT) and reflectance confocal laser microscopy (RCM) allow noninvasive imaging diagnostics of the skin. Since the indication for a biopsy in children is generally made cautiously, OCT and KLM can be helpful in the clarification of pediatric skin lesions. In addition, biopsies only represent a snapshot of a small area of the skin, while noninvasive methods allow several locations to be examined over time, so that dynamic changes and the course of therapy can also be determined. In pediatric dermatology, these diagnostic methods are particularly suitable for the clarification of atypical pigment lesions, for infectious dermatoses such as scabies or tinea, and for the diagnosis of inflammatory and degenerative dermatoses.

Line-field confocal optical coherence tomography for three-dimensional skin imaging

This paper reports on the latest advances in line-field confocal optical coherence tomography (LC-OCT), a recently invented imaging technology that now allows the generation of either horizontal (x × y) section images at an adjustable depth or vertical (x × z) section images at an adjustable lateral position, as well as three-dimensional images. For both two-dimensional imaging modes, images are acquired in real-time, with real-time control of the depth and lateral positions. Three-dimensional (x × y × z) images are acquired from a stack of horizontal section images. The device is in the form of a portable probe. The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes. Using a supercontinuum laser as a broadband light source and a high numerical microscope objective, an isotropic spatial resolution of ∼1 µm is achieved. The field of view of the three-dimensional images is 1.2 mm × 0.5 mm × 0.5 mm (x × y × z). Images of skin tissues are presented to demonstrate the potential of the technology in dermatology.