Reflectance confocal microscopy-guided laser ablation of basal cell carcinomas: initial clinical experience

Lasers for the Treatment of Nonmelanoma Skin Cancer: A Systematic Review of the Literature

BACKGROUND

Lasers may present an alternative treatment modality for the management of nonmelanoma skin cancer (NMSC).

OBJECTIVE

To investigate lasers as a definitive treatment of NMSC.

METHODS

A comprehensive search was performed on MEDLINE, the Cochrane Library, and the National Institutes of Health (www.clinicaltrials.gov). The Preferred Reporting Items for Systematic Reviews and Meta-Analysis was used to finalize a list of relevant literature studies evaluating the role of laser therapy for NMSC. Articles published through May 1, 2023, were included.

RESULTS

The authors identified 37 studies investigating nonablative and ablative lasers alone and in combination with other lasers, noninvasive imaging, and additional modalities for the treatment of basal cell carcinomas, 10 focusing on squamous cell carcinoma in situ and 3 focusing on the treatment of both basal and squamous cell carcinomas.

CONCLUSION

Although surgical management continues to be superior to laser therapy for the management of high-risk and cosmetically sensitive tumors, laser therapy may be an acceptable alternative for low-risk lesions on the trunk and extremities. However, further studies are needed to optimize parameters, determine maximal efficacy, and provide long-term follow-up before the adoption of laser therapy for NMSC into daily clinical practice.

Looking into the Skin in Health and Disease: From Microscopy Imaging Techniques to Molecular Analysis

The skin is a complex organ that includes a wide variety of tissue types with different embryological origins [...].

Skin Cancer Pathobiology at a Glance: A Focus on Imaging Techniques and Their Potential for Improved Diagnosis and Surveillance in Clinical Cohorts

Early diagnosis is essential for completely eradicating skin cancer and maximizing patients' clinical benefits. Emerging optical imaging modalities such as reflectance confocal microscopy (RCM), optical coherence tomography (OCT), magnetic resonance imaging (MRI), near-infrared (NIR) bioimaging, positron emission tomography (PET), and their combinations provide non-invasive imaging data that may help in the early detection of cutaneous tumors and surgical planning. Hence, they seem appropriate for observing dynamic processes such as blood flow, immune cell activation, and tumor energy metabolism, which may be relevant for disease evolution. This review discusses the latest technological and methodological advances in imaging techniques that may be applied for skin cancer detection and monitoring. In the first instance, we will describe the principle and prospective clinical applications of the most commonly used imaging techniques, highlighting the challenges and opportunities of their implementation in the clinical setting. We will also highlight how imaging techniques may complement the molecular and histological approaches in sharpening the non-invasive skin characterization, laying the ground for more personalized approaches in skin cancer patients.

Optical imaging guided- 'precision' biopsy of skin tumors: a novel approach for targeted sampling and histopathologic correlation

Dermoscopy and reflectance confocal microscopy (RCM) are two noninvasive, optical imaging tools used to facilitate clinical diagnosis. A biopsy technique that produces exact correlation with optical imaging features is not previously reported. To evaluate the applications of a novel feature-focused 'precision biopsy' technique that correlates clinical-dermoscopy-RCM findings with histopathology. This was a prospective case-series performed during August 2017 and June 2019 at a tertiary care cancer. We included consecutive patients requiring a precise dermoscopy-RCM-histopathologic correlation. We performed prebiopsy dermoscopy and both wide probe and handheld RCM of suspicious lesions. Features of interest were isolated with the aid of paper rings and a 2 mm punch biopsy was performed in the dermoscopy- or RCM-highlighted area. Tissue was processed either en face or with vertical sections. One-to-one correlation with histopathology was obtained. Twenty-three patients with 24 lesions were included in the study. The mean age was 64.6 years (range 22-91 years); there were 16 (69.6%) males, 14 (58.3%) lesions biopsied were on head and neck region. We achieved tissue-conservation diagnosis in 100% (24/24), 13 (54.2%) were clinically equivocal lesions, six (25%) were selected for 'feature correlation' of structures on dermoscopy or RCM, and five (20.8%) for 'correlation of new/unknown' RCM features seen on follow-up. The precision biopsy technique described herein is a novel method that facilitates direct histopathological correlation of dermoscopy and RCM features. With the aids of optical imaging devices, accurate diagnosis may be achieved by minimally invasive tissue extraction.

Application of Cellular Resolution Full-Field Optical Coherence Tomography in vivo for the Diagnosis of Skin Tumours and Inflammatory Skin Diseases: A Pilot Study

BACKGROUND

Optical coherence tomography (OCT) has been shown to provide non-invasive diagnosis of common skin neoplasms, especially basal cell carcinoma. OCT produces a cross-sectional view of the tissue, similar to a traditionally sectioned histopathological view, but the resolution of conventional OCT is low and thus limits clinical application.

OBJECTIVES

This study aimed to investigate the application ability of a full-field (FF)OCT system which was newly developed to scan the skin at the cellular level.

METHODS

Patients with skin tumours or inflammatory lesions warranting biopsy were consecutively enrolled. All lesions underwent clinical, dermoscopic, and OCT assessment, followed by routine biopsy. The adjacent normal skin was scanned for comparison. OCT images were interpreted (blinded to the biopsy results) and then compared with the histopathological diagnosis.

RESULTS

A total of 111 patients with 115 lesions completed the protocol, including 80 skin tumours, 28 inflammatory diseases, and 7 other diseases. Of the OCT images, 43.5% were of good quality and show expected features. Identifiable features of actinic keratosis, Bowen's disease, basal cell carcinoma, extramammary Paget's disease, seborrheic keratosis, large cell acanthoma, bullous pemphigoid, interface dermatitis, lichenoid tissue reaction, and psoriasis were demonstrated. Lesions are located deeply, and so some features were out of the field of view, accounting for 40.0% (46/115).

CONCLUSIONS

This study expanded the ability of FFOCT for the clinical diagnosis of various skin conditions. This new optical technique can clearly visualise skin lesions located in the epidermis and upper dermis. It provided an effective way to perform digital skin biopsy in superficial skin diseases.

In vivo imaging characterization of basal cell carcinoma and cutaneous response to high-dose ionizing radiation therapy: A prospective study of reflectance confocal microscopy, dermoscopy, and ultrasonography

BACKGROUND

Radiation therapy (RT) is a treatment option for select skin cancers. The histologic effects of RT on normal skin or skin cancers are not well characterized. Dermoscopy, high-frequency ultrasonography (HFUS), and reflectance confocal microscopy (RCM) are noninvasive imaging modalities that may help characterize RT response.

OBJECTIVES

To describe changes in the tumor and surrounding skin of patients with basal cell carcinoma (BCC) treated with RT.

METHODS

The study was conducted between 2014 and 2018. Patients with biopsy-proven BCCs were treated with 42 Gy in 6 fractions using a commercially available brachytherapy device. Dermoscopy, HFUS, and RCM were performed before treatment and at 6 weeks, 3 months, and 12 months after RT.

RESULTS

A total of 137 imaging assessments (RCM + dermoscopy + HFUS) were performed in 12 patients. BCC-specific features were present in 81.8%, 91%, and 17% of patients imaged with dermoscopy, RCM, and HFUS at baseline, respectively, before treatment. After treatment, the resolution of these features was noted in 33.4%, 91.7%, and 100% of patients imaged with the respective modalities. No recurrences were seen after a mean of 31.7 months of follow-up.

LIMITATIONS

Small sample size and no histopathologic correlation.

CONCLUSION

Dermoscopy and HFUS were not as reliable as RCM at characterizing BCC RT response.

Evaluation of a Combined Reflectance Confocal Microscopy-Optical Coherence Tomography Device for Detection and Depth Assessment of Basal Cell Carcinoma

Importance

The limited tissue sampling of a biopsy can lead to an incomplete assessment of basal cell carcinoma (BCC) subtypes and depth. Reflectance confocal microscopy (RCM) combined with optical coherence tomography (OCT) imaging may enable real-time, noninvasive, comprehensive three-dimensional sampling in vivo, which may improve the diagnostic accuracy and margin assessment of BCCs.

Objective

To determine the accuracy of a combined RCM-OCT device for BCC detection and deep margin assessment.

Design, Setting, and Participants

This pilot study was carried out on 85 lesions from 55 patients referred for physician consultation or Mohs surgery at Memorial Sloan Kettering Skin Cancer Center in Hauppauge, New York. These patients were prospectively and consecutively enrolled in the study between January 1, 2017, and December 31, 2017. Patients underwent imaging, with the combined RCM-OCT probe, for previously biopsied, histopathologically confirmed BCCs and lesions clinically or dermoscopically suggestive of BCC. Only patients with available histopathologic examination after imaging were included.

Main Outcomes and Measures

Improvements in sensitivity, specificity, and diagnostic accuracy for BCC using the combined RCM-OCT probe as well as the correlation between OCT-estimated depth and histopathologically measured depth were investigated.

Results

In total, 85 lesions from 55 patients (27 [49%] were female and 28 [51%] were male with a median [range] age of 59 [21-90] years) were imaged. Imaging was performed on 25 previously biopsied and histopathologically confirmed BCCs and 60 previously nonbiopsied but clinically or dermoscopically suspicious lesions. Normal skin and BCC features were correlated and validated with histopathologic examination. In previously biopsied lesions, residual tumors were detected in 12 of 25 (48%) lesions with 100% sensitivity (95% CI, 73.5%-100%) and 23.1% specificity (95% CI, 5.0%-53.8%) for combined RCM-OCT probe. In previously nonbiopsied and suspicious lesions, BCCs were diagnosed in 48 of 60 (80%) lesions with 100% sensitivity (95% CI, 92.6%-100%) and 75% specificity (95% CI, 42.8%-94.5%). Correlation was observed between depth estimated with OCT and depth measured with histopathologic examination: the coefficient of determination (R2) was 0.75 (R = 0.86; P < .001) for all lesions, 0.73 (R = 0.85; P < .001) for lesions less than 500 μm deep, and 0.65 (R = 0.43; P < .001) for lesions greater than 500 μm deep.

Conclusions and Relevance

Combined RCM-OCT imaging may be prospectively used to comprehensively diagnose lesions suggestive of BCC and triage for treatment. Further validation of this device must be performed on a larger cohort.

Feasibility of a Video-Mosaicking Approach to Extend the Field-of-View For Reflectance Confocal Microscopy in the Oral Cavity In Vivo

BACKGROUND

Reflectance confocal microscopy (RCM) is a developing approach for noninvasive detection of oral lesions with label-free contrast and cellular-level resolution. For access into the oral cavity, confocal microscopes are being configured with small-diameter telescopic probes and small objective lenses. However, a small probe and objective lens allows for a rather small field-of-view relative to the large areas of tissue that must be examined for diagnosis. To extend the field-of-view for intraoral RCM imaging, we are investigating a video-mosaicking approach.

METHODS

A relay telescope and objective lens were adapted to an existing confocal microscope for access into the oral cavity. Imaging was performed using metal three-dimensional-printed objective lens front-end caps with coverslip windows to contact and stabilize the tissue and set depth. Four healthy volunteers (normal oral mucosa), one patient (with an amalgam tattoo) in a clinical setting, and 20 anesthetized patients (with oral squamous cell carcinoma [OSCC]) in a surgical setting were imaged. Instead of the usual still RCM images, videos were recorded and then processed into video-mosaics. Thirty video-mosaics were read and qualitatively assessed by an expert reader of RCM images of the oral mucosa.

RESULTS

Whereas the objective lens' native field-of-view is 0.75 mm × 0.75 mm, the video-mosaics display larger areas, ranging from 2 mm × 2 mm to 4 mm × 2 mm, with resolution, morphologic detail, and image quality that is preserved relative to that observed in the original videos (individual images). Video-mosaics in healthy volunteers' and the patients' images showed cellular morphologic patterns in the lower epithelium and at the epithelial junction, and connective tissue along with capillary loops and blood flow in the deeper lamina propria. In OSCC, tumor nests could be observed along with normal looking mucosa in margin areas.

CONCLUSIONS

Video-mosaicking is a reasonably quick and efficient approach for extending the field-of-view of RCM imaging, which can, to some extent, overcome the inherent limitation of an intraoral probe's small field-of-view. Reading video-mosaics can mimic the procedure for examining pathology: initial visualization of the spatial cellular and morphologic patterns of the tumor and the spread of tumor margins over larger areas of the lesion, followed by digitally zooming (magnifying) for closer inspection of suspicious areas. However, faster processing of videos into video-mosaics will be necessary, to allow examination of video-mosaics in real-time at the bedside. Lasers Surg. Med. 51:439-451, 2019. © 2019 Wiley Periodicals, Inc.

Reflectance confocal microscopy-guided carbon dioxide laser ablation of low-risk basal cell carcinomas: A prospective study

BACKGROUND

Basal cell carcinoma (BCC) treatment modalities can be stratified by tumor subtype and recurrence risk. The main limitation of nonsurgical treatment modalities is the lack of histopathologic confirmation. Reflectance confocal microscopy (RCM) is a noninvasive imaging device that provides quasihistologic images.

OBJECTIVE

To evaluate the feasibility and efficacy of RCM-guided carbon dioxide (CO₂) laser ablation of low-risk BCCs.

METHODS

Prospective study with biopsy specimen-proven low-risk BCCs imaged with RCM. RCM was performed on these sites before and after ablation. If residual tumor was found, a new series of laser passes were performed. The patients were then monitored for recurrence clinically and with RCM.

RESULTS

Twenty-two tumor sites in 9 patients (5 men, 4 women) were imaged and treated. Median age was 59 ± 12.9 years (range, 30-74 years). Mean tumor size was 7.7 mm (range, 5-10 mm). Residual tumor was identified in 5 of 22 cases (22.7%) under RCM on immediate first-pass postablation sites, prompting additional laser passes. Median follow-up was 28.5 months (range, 22-32 months) with no recurrences found.

CONCLUSIONS

Addition of RCM to laser ablation workflow can detect subclinical persistent tumor after initial ablation and may serve as an aid to increase the efficacy of laser ablation.

Evaluation of the Response of Unresectable Primary Cutaneous Melanoma to Immunotherapy Visualized With Reflectance Confocal Microscopy: A Report of 2 Cases

Importance

Melanoma incidence and the use of systemic treatments for it are rising. Current treatment monitoring uses clinical examination and radiologic examinations; however, cutaneous involvement and cutaneous metastasis may not be well visualized. Reflectance confocal microscopy (RCM) is a US Food and Drug Administration-approved, noninvasive technology that enables visualization of the skin with quasihistological resolution.

Objective

To evaluate the feasibility of using RCM to monitor advanced melanomas treated with immunotherapy.

Design, Setting, and Participants

This case report study took place from March 2017 to June 2018 and included 2 patients with locally advanced melanoma who were not candidates for surgery or were not willing to have surgery and who were started on an immunotherapy regimen at a tertiary care cancer hospital.

Main Outcomes and Measures

Clinical and RCM findings correlated with histopathology.

Results

In the patients, locally advanced melanoma with cutaneous involvement was treated with immunotherapy (pembrolizumab in 1 patient and an ipilimumab-nivolumab combination in the other) with resulting clearance of the lesions. Use of RCM showed the disappearance of clear melanoma features seen at baseline; these findings correlated with histopathology. The response was not seen with radiologic images, such as magnetic resonance imaging and computed tomography.

Conclusions and Relevance

Although RCM will not replace larger field imaging (such as magnetic resonance imaging, positron emission tomography, and computed tomography) in the management and follow-up of melanoma or other tumors, for imaging of cutaneous involvement and disease monitoring, RCM holds promise as a novel noninvasive technique.

[Laser treatment of basal cell carcinoma]

With a clear increase in the incidence and a continuously earlier onset, the main risk factors for the development of basal cell carcinoma are still exposure to sunlight, fair skin, immunosuppression, carcinogens such as arsenic, chronic irritations and certain genodermatoses. Treatment options for localized resectionable basal cell carcinoma include micrographically controlled surgery, simple excision, curettage, laser ablation, cryosurgery, imiquimod, 5‑fluorouracil, photodynamic treatment and radiotherapy. Non-surgical treatment options are more suited for cases in which surgical procedures lead to disfigurement or functional impairments or for patients with a high surgical risk. Laser treatment, ablative and non-ablative as monotherapy or in combination can represent a meaningful treatment option in selected cases. In recent years there has been an increase in knowledge about the indications and effects of laser treatment of basal cell carcinoma; nevertheless, further studies with a high level of evidence are necessary.