Ex vivo confocal microscopy for surgical margin assessment: A histology-compared study on 109 specimens

Diagnostic accuracy of autofluorescence-Raman microspectroscopy for surgical margin assessment during Mohs micrographic surgery of basal cell carcinoma

BACKGROUND

Autofluorescence (AF)-Raman microspectroscopy is a technology that can detect residual basal cell carcinoma (BCC) on the resection margin of fresh, surgically excised tissue specimens. The technology does not require tissue fixation, staining, labelling or sectioning, and provides quantitative diagnosis maps of the surgical margins in 30 min.

OBJECTIVES

To determine the accuracy of the AF-Raman instrument in detecting incomplete BCC excisions during Mohs micrographic surgery (MMS), using histology as the reference standard.

METHODS

Skin layers from 130 patients undergoing MMS at the Nottingham University Hospitals NHS Trust (September 2022-July 2023) were investigated with the AF-Raman instrument. The layers were measured when fresh, immediately after excision. The AF-Raman results and the intraoperative assessment by Mohs surgeons were compared with a postoperative consensus-derived reference produced by three dermatopathologists. The sensitivity, specificity, and positive and negative predictive values were calculated. The study was registered with ClinicalTrials.gov (NCT03482622).

RESULTS

AF-Raman analysis was successfully completed for 125 of 130 layers and, on average, covered 91% of the specimen surface area, with the lowest surface area covered being 87% for the eyelid and the highest being 94% for forehead specimens. The AF-Raman instrument identified positive margins in 24 of 36 BCC-positive cases [67% sensitivity, 95% confidence interval (CI) 49-82] and negative margins in 65 of 89 BCC-negative cases (73% specificity, 95% CI 63-82). Only one of 12 false-negative cases was caused by misclassification by the AF-Raman algorithm. The other 11 false-negatives cases were a result of no valid Raman signal being recorded at the location of the residual BCC due to either occlusion by blood or poor contact between tissue and the cassette window. The intraoperative diagnosis by Mohs surgeons identified positive margins in 31 of 36 BCC-positive cases (86% sensitivity, 95% CI 70-95) and negative margins in 79 of 89 BCC-negative cases (89% specificity, 95% CI 81-95).

CONCLUSIONS

The AF-Raman instrument has the potential to provide intraoperative microscopic assessment of surgical margins in BCC surgery. Further improvements are required for tissue processing, to ensure complete coverage of the surgical specimens.

Ultra-fast confocal fluorescence microscopy for neck lymph node imaging in head and neck cancer

OBJECTIVES

We evaluated ultra-fast confocal fluorescence microscopy (UFCM) as a new modality for pathology practice in head and neck cancer (HNC). This was assessed through an ex vivo study to estimate the accuracy, specificity, and sensitivity of interpretation of UFCM images by pathologists for the detection of metastatic lymph nodes in HNC patients undergoing sentinel lymph node biopsy or selective or complete neck dissection.

MATERIALS AND METHODS

44 patients with 32 cN0 and 12 cN+ HNC were included. The macroscopically non-invaded fresh bisected lymph nodes were stained with acridine orange and imaged with Histolog® Scanner (UFCM). Two pathologists interpreted independently the UFCM images postoperatively and gave a consensus diagnosis in case of disagreement. The gold standard was the diagnosis based on hematoxylin-eosin-saffron (HES) sections.

RESULTS

201 lymph nodes were imaged by UFCM. Thirty nodes (15 %) were invaded on final histology: 3 with micrometastases and 27 with macrometastases. The concordance rate between the pathologists on the UFCM images was 192/201 = 95.5 % and the Cohen kappa coefficient was 0.80. The accuracy of UFCM was 95.5 % (95 %CI: 91.7 %-97.9 %) with a high specificity at 98.8 % (95 %CI: 95.8 %-99.9 %) but an insufficient sensitivity at 76.7 % (95 %CI: 57.7 %-90.1 %). The three micrometastases and four of the 27 macrometastases were missed on UFCM images.

CONCLUSION

The UFCM is providing promising detection values with a very good specificity and moderate sensitivity carrying room for improvement.

Mohs Micrographic Surgery for Cutaneous Squamous Cell Carcinoma

BACKGROUND

The first-line treatment of the localized form of cutaneous squamous cell carcinoma (cSCC) remains surgical excision. Either conventional excision (CE) with margins or Mohs micrographic surgery (MMS) may be preferred, depending on the risk factors of cSCC, the characteristics of the tumor, and the available technical facilities.

METHODS

This article presents a systematic review of the current literature spanning from 1974 to 2023, comparing outcomes of cSCC treated with MMS versus cSCC treated with conventional excision.

RESULTS

Out of the 6821 records identified through the database search, a total of 156 studies were screened, of which 10 were included in the review. The majority of the included studies showed that treatment of cSCC with MMS consistently exhibits a significantly lower risk of recurrence compared to treatment with CE. In addition, MMS is emerging as the preferred technique for the resection of cSCC located in aesthetically or functionally challenging anatomical areas.

CONCLUSION

The studies generally demonstrate that MMS is a safer and more effective treatment of cSCC than CE. Nevertheless, outcomes such as recurrence rates and cost-effectiveness should be assessed more precisely, in order to allow for a more tailored approach in determining the appropriate indication for the use of MMS.

Ex Vivo Fluorescence Confocal Microscopy for Intraoperative Examinations of Lung Tumors as Alternative to Frozen Sections-A Proof-of-Concept Study

BACKGROUND

Intraoperative frozen sections (FS) are frequently used to establish the diagnosis of lung cancer when preoperative examinations are not conclusive. The downside of FS is its resource-intensive nature and the risk of tissue depletion when small lesions are assessed. Ex vivo fluorescence confocal microscopy (FCM) is a novel microimaging method for loss-free examinations of native materials. We tested its suitability for the intraoperative diagnosis of lung tumors.

METHODS

Samples from 59 lung resection specimens containing 45 carcinomas were examined in the FCM. The diagnostic performance in the evaluation of malignancy and histological typing of lung tumors was evaluated in comparison with FS and the final diagnosis.

RESULTS

A total of 44/45 (98%) carcinomas were correctly identified as malignant in the FCM. A total of 33/44 (75%) carcinomas were correctly subtyped, which was comparable with the results of FS and conventional histology. Our tests documented the excellent visualization of cytological features of normal tissues and tumors. Compared to FS, FCM was technically less demanding and less personnel intensive.

CONCLUSIONS

The ex vivo FCM is a fast, effective, and safe method for diagnosing and subtyping lung cancer and is, therefore, a promising alternative to FS. The method preserves the tissue without loss for subsequent examinations, which is an advantage in the diagnosis of small tumors and for biobanking.

Breast tissue imaging atlas using ultra-fast confocal microscopy to identify cancer lesions

New generation ultra-fast fluorescence confocal microscopy (UFCM) allows to image histological architecture of fresh breast tissue and may be used for ex vivo intraoperative analysis for margin status. The criteria to identify breast tumoral and non-tumoral tissues in UFCM images are still objects of investigation. The objective of the study was to create an atlas of ex vivo UFCM images of breast tissues and breast carcinomas based on the first extensive collection of large field-of-view UFCM breast images. One hundred sixty patients who underwent conserving surgery for breast cancer were included. Their fresh surgical specimens were sliced, stained with acridine orange, and imaged at high resolution with large-field-of-view UFCM. The resulting images were digitally false colored to resemble frozen sections. Each UFCM image was correlated with the corresponding definitive histology. Representative images of normal tissue, inflammation, benign lesions, invasive carcinoma (IC), and ductal carcinoma in situ (DCIS) were collected. A total of 320 large-field images were recorded from 58 IC of no special type, 44 invasive lobular carcinomas, 1 invasive mucinous carcinoma, 47 DCIS, 2 lobular carcinomas in situ, and 8 specimens without cancer. Representative images of the main components of the normal breast and the main types of ICs and DCIS were annotated to establish an UFCM atlas. UFCM enables the imaging of the fresh breast tissue sections. Main morphological criteria defined in traditional histopathology such as tissue architecture and cell features can be applied to describe UFCM images content. The generated atlas of the main normal or tumoral tissue features will support the adoption of this optical technology for the intraoperative examination of breast specimens in clinical practice as it can be used to train physicians on UFCM images and develop artificial intelligence algorithms. Further studies are needed to document rare breast lesions.

SENOSI Confocal Microscopy: A New and Innovating Way to Detect Positive Margins in Non-Palpable Breast Cancer?

In Switzerland, breast cancer is the leading cancer among women, with breast-conserving surgery (BCS) being the preferred treatment for small tumors. The margin status post-surgery is a critical predictor of local recurrence. Achieving negative margins remains a challenge, leading to re-excision in 20-30% of cases. Traditional methods like intraoperative examination palpation and radiography have limitations in assessing excised margins. This study introduces the Histolog® Scanner, a confocal microscopy tool, as a potential solution. It provides real-time images of tissue architecture, allowing for rapid and accurate assessment of excised margins. Our research compared the Histolog® Scanner with standard per-operative radiography in patients with non palpable breast cancer. Preliminary results indicate that the Histolog® Scanner offers a reliable and time-efficient method for margin assessment, suggesting its potential for clinical integration.

Imaging of lumpectomy surface with large field-of-view confocal laser scanning microscope for intraoperative margin assessment - POLARHIS study

INTRODUCTION

Breast-conserving surgery (BCS) in case of breast cancer and/or in-situ-carcinoma lesions (DCIS) intends to completely remove breast cancer while saving healthy tissue as much as possible to achieve better aesthetic and psychological outcomes for the patient. Such modality should result in postoperative tumor-free margins of the surgical resection in order to carry on with the next therapeutical steps of the patient care. However, 10-40% of patients undergo more than one procedure to achieve acceptable cancer-negative margins. A 2nd operation or further operation (re-operation) has physical, psychological, and economic consequences. It also delays the administration of adjuvant therapy, and has been associated with an elevated risk of local and distant disease relapse. In addition, a high re-operation rate can have significant economic effects - both for the service provider and for the payer. A more efficient intraoperative assessment of the margin may address these issues. Recently, a large field-of-view confocal laser scanning microscope designed to allow real-time intraoperative margin assessment has arrived on the market - the Histolog Scanner. In this paper, we present the first evaluation of lumpectomy margins assessment with this new device.

MATERIALS AND METHODS

40 consecutive patients undergoing BCS with invasive and/or DCIS were included. The whole surface of the surgical specimens was imaged right after the operation using the Histolog Scanner (HLS). The assessment of all the specimen margins was performed intraoperatively according to the standard-of-care of the center which consists of combined ultrasound (IOUS) and/or conventional specimen radiography (CSR), and gross surgical inspection. Margin assessment on HLS images was blindly performed after the surgery by 5 surgeons and one pathologist. The capabilities to correctly determine margin status in HLS images was compared to the final histopathological assessment. Furthermore, the potential reduction of positive-margin and re-operation rates by utilization of the HLS were extrapolated.

RESULTS

The study population included 7/40 patients with DCIS (17.5%), 17/40 patients with DCIS and invasive ductal cancer (IDC NST) (42.5%), 10/40 patients with IDC NST (25%), 4/40 with invasive lobular cancer (ILC) (10%), and 1/40 patients with a mix of IDC NST, DCIS, and ILC. Clinical routine resulted in 13 patients with positive margins identified by final histopathological assessment, resulting in 12 re-operations (30% re-operation rate). Amongst these 12 patients, 10 had DCIS components involved in their margin, confirming the importance of improving the detection accuracy of this specific lesion. Surgeons, who were given a short familiarization on HLS images, and a pathologist were able to detect positive margins in 4/12 and 7/12 patients (33% and 58%), respectively, that were missed by the intraoperative standard of care. In addition, a retrospective analysis of the HLS images revealed that cancer lesions can be identified in 9/12 (75%) patients with positive margins.

CONCLUSION

The present study presents that breast cancer can be detected by surgeons and pathologists in HLS images of lumpectomy margins leading to a potential reduction of 30% and 75% of the re-operations. The Histolog Scanner is easily inserted into the clinical workflow and has the potential to improve the intraoperative standard-of-care for the assessment of breast conserving treatments. In addition, it has the potential to increase oncological safety and cosmetics by avoiding subsequent resections and can also have a significant positive economic effect for service providers and cost bearers. The data presented in this study will have to be further confirmed in a prospective phase-III-trial.