Use of handheld reflectance confocal microscopy for in vivo diagnosis of solitary facial papules: a case series

Detection of sebaceous gland hyperplasia with dermoscopy and reflectance confocal microscopy

Background

Sebaceous gland hyperplasia (SGH) is a benign cutaneous proliferation of the sebaceous glands that are mostly present on the face or the neck of older adults. They typically appear as single or multiple soft umbilicated papules; however, in challenging cases, it can be difficult to distinguish them from trichoepitheliomas, base cell carcinomas, or other tumors. Although pathological results have diagnostic value, the significance of non-invasive examinations in diagnosis and differential diagnosis is also worth exploring.

Objectives

This study aimed to describe the dermoscopic and reflectance confocal microscopy (RCM) features of SGH.

Methods

A total of 31 patients diagnosed with SGH, according to clinical and histopathological standards, were examined using dermoscopy and RCM between March 2018 and January 2022.

Results

Dermoscopically, lesions revealed a yellowish-red background and a faint-yellow background in 25 (80.65%) and six cases (19.35%), respectively. White-yellowish lobulated structures in the center of the lesion were present in 31 patients (100%) and umbilications in 19 patients (61.29%). Crown vessels at the periphery of the lesions were observed in 11 patients (35.48%), whereas irregular linear vessels were observed on the surface of the lesions in 18 patients (58.06%). Under RCM, all lesions presented a honeycomb pattern in the epidermis and the typical morulae-shaped sebaceous lobules in the dermis. A dilated follicular infundibulum was observed in 15 patients (48.39%) and dilated vessels in 26 patients (83.87%).

Conclusion

Dermoscopy and RCM enabled us to describe the imaging features of SGH. Combining these two useful tools provides a non-invasive basis for accurate clinical diagnosis.

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.

Significance of Dermoscopy in Association with Clinical Features in Differentiation of Basal Cell Carcinoma and Benign Trichoblastic Tumours

Background: Although basal cell carcinoma (BCC) can, in the majority of cases, be diagnosed based on clinical and dermoscopic assessment, a potential overlap with benign adnexal skin tumours seems to exist, including trichoblastic tumours (TT). Methods: Retrospective analysis of clinical and dermoscopic features of benign TT and BCC cases was performed to develop a diagnostic algorithm with a potential utility in clinical practice. Results: In the study, 502 histopathologically confirmed BCC cases were compared with 61 TT (including 44 TB (72.13%), 10 TE (16.39%) and 7 DTE (11.48%]). Patients in the BCC group were statistically older (mean age was 71.4 vs. 64.4 years, respectively; p = 0.009). BCC presented generally as larger tumours (mean tumour size 11.0 vs. 8.2 mm for the TT group; p = 0.001) and was more frequently associated with clinically visible ulceration (59.4% vs. 19.7%, respectively; p < 0.001). Comparison of lesion morphology, clinically visible pigmentation, and anatomical location did not show significant differences between the analysed groups. Dermoscopically visible ulceration was significantly more common in the BCC group compared to the TT group (52.2% vs. 14.8%; p < 0.0001). Pigmented structures, specifically brown dots and brown globules, were significantly more prevalent in the TT group (32.8% vs. 11.4%; p = 0.0001 and 29.5% vs. 8.2%; p <0.0001). Similarly, TT more commonly than BCC showed the presence of cloudy/starry milia-like cysts (26.2% vs. 11.6%; p = 0.0031) and yellow globules (16.4% vs. 7.2%; p = 0.033). Conclusions: Despite differences in frequency of clinical and dermoscopic features between BCC and TT in the studied group, differential diagnosis based on these variables is not reliable. Histopathological examination remains a diagnostic gold standard in differentiation of BCC and TT.

Automated video-mosaicking approach for confocal microscopic imaging in vivo: an approach to address challenges in imaging living tissue and extend field of view

We describe a computer vision-based mosaicking method for in vivo videos of reflectance confocal microscopy (RCM). RCM is a microscopic imaging technique, which enables the users to rapidly examine tissue in vivo. Providing resolution at cellular-level morphology, RCM imaging combined with mosaicking has shown to be highly sensitive and specific for non-invasively guiding skin cancer diagnosis. However, current RCM mosaicking techniques with existing microscopes have been limited to two-dimensional sequences of individual still images, acquired in a highly controlled manner, and along a specific predefined raster path, covering a limited area. The recent advent of smaller handheld microscopes is enabling acquisition of videos, acquired in a relatively uncontrolled manner and along an ad-hoc arbitrarily free-form, non-rastered path. Mosaicking of video-images (video-mosaicking) is necessary to display large areas of tissue. Our video-mosaicking methods addresses this need. The method can handle unique challenges encountered during video capture such as motion blur artifacts due to rapid motion of the microscope over the imaged area, warping in frames due to changes in contact angle and varying resolution with depth. We present test examples of video-mosaics of melanoma and non-melanoma skin cancers, to demonstrate potential clinical utility.

Reflectance confocal microscopy features of facial angiofibromas

Facial angiofibromas are benign tumors presenting as firm, dome-shaped, flesh-colored to pink papules, typically on the nose and adjoining central face. Clinically and dermoscopically they can mimic melanocytic nevi or basal cell carcinomas (BCC). Reflectance confocal microscopy (RCM) is a noninvasive imaging tool that is useful in diagnosing melanocytic and non-melanocytic facial lesions. To date no studies have described the RCM features of facial angiofibromas. Herein, we present two cases of facial angiofibromas that were imaged with RCM and revealed tumor island-like structures that mimicked BCC, leading to skin biopsy.

The influence of different shavers on the skin quantified by non-invasive reflectance confocal microscopy

BACKGROUND

The impact of personal care devices on skin is mainly assessed using subjective tools. However, new objective, accurate non-invasive in vivo imaging techniques have been developed. The aim of this study was to evaluate the ability of reflectance confocal microscopy (RCM) in quantifying morphological impact of shavers on skin. Furthermore, tape stripping (TS) as method to study morphological impact of shavers was evaluated.

METHODS

In 12 healthy male subjects, for two consecutive days, a split-face test was performed in the neck; on one side a shaver was applied, while the other side was exposed to TS. The stratum corneum (SC) thickness was quantified using RCM and sensory observations were evaluated using questionnaires.

RESULTS

Shavers with a different impact on skin, can be discriminated by RCM; shaver B removed more SC after application than the skin friendlier shaver A. Furthermore, the changes in SC thickness induced by TS corresponded well to that of the shavers.

CONCLUSION

RCM is able to quantify the impact of different shavers on skin. Besides, TS appeared to be a suitable model mimicking the mechanical impact of shavers on skin. RCM in combination with the TS model appeared to be a suitable minimally invasive model to obtain morphological and cell biological data on skin-material interactions caused by different personal care devices.

[High-resolution ultrasonography for differential diagnosis between nodular basal carcinoma and sebaceous hyperplasia of the face: A pilot study]

BACKGROUND

Clinical differential diagnosis between incipient nodular basal carcinoma (NBC) and sebaceous hyperplasia (SH) of the face is difficult in some cases. A comparative histological analysis of these two entities led us to the hypothesis that 20MHz high-resolution ultrasonography (HRUS) may enable differentiation between NBC and SH.

PATIENTS AND METHODS

Seventy-seven facial tumours requiring histological confirmation to distinguish between NBC and SH were scanned using HRUS before excision. No other imaging technique was used. The ultrasound scans were submitted to two blinded reviewers who were asked to classify the ultrasound pictures of the tumours as either hypoechoic or isoechoic/hyperechoic. Hypoechogenicity was defined as a diagnostic criterion for NBC.

RESULTS

Reviewer response reproducibility for 2 images of the same tumour was 90%. Both reviewers agreed regarding the echogenicity classification of an image in 87.4% of cases. The sensitivity of the procedure was 90.9% for detection of NBC and 89.4% for detection of malignant lesions. Specificity was 69.6% for detection of basal cell carcinomas and 78.8% for detection of malignant lesions.

DISCUSSION

HRUS is a non-invasive examination technique with excellent sensitivity for the detection of NBC in differential diagnosis with SH. Hypoechogenicity is not specific to NBC. The sensitivity of HRUS in our study suffered as a result of ultrasonography difficulties regarding unexpected differential diagnoses of NBC as well as tumour localisation in seborrhoeic areas.

Through the looking glass: Basics and principles of reflectance confocal microscopy

Reflectance confocal microscopy (RCM) offers high-resolution, noninvasive skin imaging and can help avoid obtaining unnecessary biopsy specimens. It can also increase efficiency in the surgical setting by helping to delineate tumor margins. Diagnostic criteria and several RCM algorithms have been published for the differentiation of benign and malignant neoplasms. We provide an overview of the basic principles of RCM, characteristic RCM features of normal skin and cutaneous neoplasms, and the limitations and future directions of RCM.