Confocal laser scanning microscopy in micrographic surgery (three-dimensional histology) of basal cell carcinomas

Diagnosis of Basal Cell Carcinoma with Ex-vivo Confocal Laser Scanning Microscopy in a Real-life Setting

Ex-vivo confocal laser scanning microscopy provides a rapid alternative to routine histological processing using haematoxylin and eosin-stained sections. Previous studies suggest high diagnostic accuracy in basal cell carcinoma. This study investigates the diagnostic accuracy of confocal laser scanning microscopy reporting of basal cell carcinoma in a real-life setting and compares reporting by dermatopathologists inexperienced in use of confocal laser scanning microscopy with reporting by an expert in confocal laser scanning microscopy. A total of 334 confocal laser scanning microscopy scans were diagnosed by 2 dermatopathologists inexperienced in the diagnosis of confocal laser scanning microscopy as well as an experienced examiner of confocal laser scanning microscopy scans. The inexperienced examiners achieved a sensitivity of 59.5/71.1% and specificity of 94.8/89.8%. The experienced examiner achieved a sensitivity of 78.5% and specificity of 84.8%. Detection of tumour remnants in margin controls showed insufficient values among inexperienced (30.1/33.3%) and experienced (41.7%) investigators. The results of this study, of real-life setting basal cell carcinoma reporting with confocal laser scanning microscopy, found a lower diagnostic accuracy than published data regarding artificial settings. A poor accuracy in tumour margin control is clinically relevant and could restrict the use of confocal laser scanning microscopy in clinical routine. Prior knowledge of haematoxylin and eosin trained pathologists can be partially transferred to the reporting of confocal laser scanning microscopy scans; however, specific training is recommended.

Ex vivo confocal microscopy: an emerging technique in dermatology

This review aims to give an overview of the current available applications of ex vivo confocal microscopy (EVCM) in dermatology. EVCM is a relatively new imaging technique that allows microscopic examination of freshly excised unfixed tissue. It enables a rapid examination of the skin sample directly in the surgery room and thus represents an alternative to the intraoperative micrographic control of the surgical margins of cutaneous tumors by standard microscopic examination on cryopreserved sections during Mohs surgery. Although this technique has mainly been developed for the margin’s control of basal cell carcinoma, many other skin tumors have been studied, including melanoma. Use of EVCM is continuing to evolve, and many possible applications are under investigation, such as the study of nails and hair diseases and the diagnosis of skin infections.

In Vivo and Ex Vivo Confocal Microscopy for Dermatologic and Mohs Surgeons

Confocal microscopy is a modern imaging device that has been extensively applied in skin oncology. More specifically, for tumor margin assessment, it has been used in two modalities: reflectance mode (in vivo on skin patient) and fluorescence mode (on freshly excised specimen). Although in vivo reflectance confocal microscopy is an add-on tool for lentigo maligna mapping, fluorescence confocal microscopy is far superior for basal cell carcinoma and squamous cell carcinoma margin assessment in the Mohs setting. This article provides a comprehensive overview of the use of confocal microscopy for skin cancer margin evaluation.

S1 guideline: microscopically controlled surgery (MCS)

When using procedures that enable complete examination of surgical margins (3D histology), microscopically controlled surgery (MCS) represents a safe and proven method to confirm R0 resection of infiltrating tumors, especially at problematic sites, while preserving the adjacent tissue. This allows for excellent or good aesthetic results that are superior (cryosurgery, short-range irradiation) or equivalent (PDT) to nonsurgical and less safe procedures (PDT).

Ex Vivo (Fluorescence) Confocal Microscopy in Surgical Pathology: State of the Art

First developed in 1957, confocal microscopy is a powerful imaging tool that can be used to obtain near real-time reflected light images of untreated human tissue with nearly histologic resolution. Besides its research applications, in the last decades, confocal microscopy technology has been proposed as a useful device to improve clinical diagnosis, especially in ophthalmology, dermatology, and endomicroscopy settings, thanks to advances in instrument development. Compared with the wider use of the in vivo tissue assessment, ex vivo applications of confocal microscopy are not fully explored. A comprehensive review of the current literature was performed here, focusing on the reliable applications of ex vivo confocal microscopy in surgical pathology and on some potential evolutions of this new technique from pathologists' viewpoint.

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.

Detection of skin cancer margins in Mohs excisions with high-speed strip mosaicing confocal microscopy: a feasibility study

BACKGROUND

Fluorescence confocal mosaicing microscopy is an emerging technology for rapid imaging of nuclear and morphological detail directly in excised tissue, without the need for frozen or fixed section processing. Basal cell carcinomas (BCCs) can be detected with high sensitivity and specificity in Mohs excisions with this approach. For translation to clinical trials and towards potentially routine implementation, a new and faster approach called strip mosaicing confocal microscopy was recently developed.

OBJECTIVES

To perform a preliminary assessment of fluorescence strip mosaicing confocal microscopy for detecting skin cancer margins in Mohs excisions.

METHODS

Tissue samples from 17 Mohs cases were imaged in the form of strip mosaics. Each mosaic was divided into two halves (submosaics) and graded by a Mohs surgeon and a dermatologist who were blinded to the pathology. The 34 submosaics were compared with the corresponding Mohs pathology.

RESULTS

The overall image quality was excellent for resolution, contrast and stitching in the 34 submosaics. Components of normal skin including the epidermis, dermis, dermal appendages and subcutaneous tissue were easily visualized. The preliminary measures of sensitivity and specificity were both 94% for detecting skin cancer margins.

CONCLUSIONS

The new strip mosaicing approach represents another advance in confocal microscopy for imaging of large areas of excised tissue. Strip mosaicing may enable rapid assessment of BCC margins in fresh excisions during Mohs surgery and may serve as an adjunct to frozen pathology.

Rapid lump examination (RLE) - a new tool for Mohs surgery?

BACKGROUND

"Micrographic surgery" spares tissue and results in fewer recurrences. Various techniques have been described using paraffin-embedded and cryostat sections or even optical sections from ex vivo confocal laser scanning microscopy. The presented technique is the rapid direct microscopy of the surface of a specimen (lump) for a pathological examination (RLE).

METHODS

Fresh surgical tissue was stained first without sectioning and then was examined directly under microscope. A 95 sec staining protocol for basal cell carcinoma (BCC) was established. 129 specimens were examined using a digital microscope and 78 specimens using a stereo microscope.

RESULTS

RLE had a high diagnostic accuracy compared to paraffin-embedded H&E-stained sections. Sensitivity and specificity of RLE was 91 % and 90 % for the digital and 90 % and 94 % for the stereo microscope. In addition we developed a 7 min RLE-immunohistology protocol using the BerEp4-antibody.

DISCUSSION

RLE is a simple and accurate technique for fresh tissue examination. Here, the technique has been established for BCC but the principle may also be transferred to histological bedside diagnosis of other tumors. The technique does not alter or destroy tissue, so that after RLE was done subsequent conventional histology is still possible. RLE might yield a time- and cost-saving diagnosis in micrographic surgery.