Reflectance Confocal Microscopy: An Overview of Technology and Advances in Telepathology
The value of in vivo reflectance confocal microscopy (RCM) as a noninvasive adjunctive tool in dermatology has steadily advanced since its inception. With RCM, dermatologists can view horizontal sections of lesions in a resolution comparable to histology, observe dynamic processes in living skin, and monitor lesion evolution longitudinally. This article will compare RCM to dermoscopy and histology, review the general principles of the microscope, describe the findings seen on confocal images, and discuss the clinical applications of this noninvasive tool. Additionally, we describe a telepathology network dedicated to the transfer of confocal images to remote dermatopathologists for interpretation. Finally, we will discuss the adoption of RCM and the telepathology network in clinical practice.
Practice Points
- In vivo reflectance confocal microscopy (RCM) is a noninvasive modality for the assessment of physiologic and pathologic conditions of the skin.
- Similar to dermoscopy, RCM allows lesions to be analyzed noninvasively, and similar to histology, RCM images provide high resolution in both vertical and horizontal planes.
- Utilizing RCM as an adjunctive tool can help improve clinical diagnostic accuracy, reducing the number of biopsies of benign lesions.
- Incorporating RCM and a telepathology network into the workflow of a private practice may be valuable for dermatologists and primary care physicians.
Practical Application
A dermatology practice collaborated with a dermatopathology office to examine the feasibility of incorporating RCM and the telepathology network into the workflow of a private practice while creating a comprehensive library of cutaneous pathologies. A physician who did not have prior knowledge of RCM was selected for training with the goal to become proficient at operating the confocal microscope and interpreting the images. A dermatopathologist (also a confocal diagnostic reader) performed the histopathologic diagnoses of the lesions and correlated findings to confocal images.
Once images were captured using a standardized protocol, the lesion was biopsied according to standard of care. The images were sent over the telepathology network for interpretation and correlation to the histologic specimen by the dermatopathologist. These images were then stored on a secure server for use as a reference and educational tool for other diagnostic readers. We successfully achieved our goal of assisting with the development and integration of RCM and the telepathology network into the workflow of a busy private practice while building an extensive image library, thus showing potential use for other private practitioners.
Limitations of RCM
Although RCM may provide diagnostic information for many epidermal and papillary dermal lesions, it is not practical for predominantly dermal lesions or for providing prognostic information of invasive malignancies. Maximal imaging depth is 350 mm, but structures can truly be delineated at only approximately 250 μm (papillary dermis).2 Evaluation is further challenged with hypertrophic or hyperkeratotic lesions as well as those located on glabrous skin. Compared to histology, RCM resolution is slightly lower and nuclear features are not easily seen due to their weak backscattering effect.2 There are no adverse effects related to operator use; however, use may be limited if the patient has an allergy to the mediums used or to adhesive tape.
Challenges faced in integrating the technology into our practice include the machine size, time constraints, and reimbursement issues. Although not available in our office, smaller clinical devices exist (including a handheld RCM device that launched in 2007) and continue to be developed for future implementation. In our practice, capturing an image of 1 lesion took up to 20 minutes, but other protocols may necessitate only 10 minutes. Reimbursement for the imaging and image-reading procedures currently is being pursued.
Conclusion
In vivo RCM was developed as a noninvasive modality for the assessment of physiologic and pathologic conditions of the skin. Cellular and subcellular structures as well as dynamic processes are observed without destruction of tissue. The morphologic features seen in RCM are comparable to those demonstrated with histology and dermoscopy. Despite current challenges, RCM has been shown to be an advantageous diagnostic tool, a guide to evaluating benign and malignant lesions, an adjunct to Mohs micrographic surgery via presurgical mapping of tumor margins, and a monitoring tool to establish treatment responses and efficacy. Reflectance confocal microscopy has steadily gained acceptance in clinical dermatology over the last decade, and the number of users continues to grow. With the continued efforts in advancing research, including usage of the telepathology network, we believe these tools will prove to be valuable in the private practice setting, both in the fields of dermatology and primary care.
Acknowledgment
The authors thank Caliber Imaging & Diagnostics, Inc (Rochester, New York), for providing the RCM imaging system with associated disposable supplies and the reader workstation for this review.
