Detection of basal cell carcinomas in Mohs excisions with fluorescence confocal mosaicing microscopy

Abstract

BACKGROUND: High-resolution real-time imaging of human skin is possible with a confocal microscope either in vivo or in freshly excised tissue ex vivo. Nuclear and cellular morphology is observed in thin optical sections, similar to that in conventional histology. Contrast agents such as acridine orange in fluorescence and acetic acid in reflectance have been used in ex vivo imaging to enhance nuclear contrast. OBJECTIVE: To evaluate the sensitivity and specificity of ex vivo real-time imaging with fluorescence confocal mosaicing microscopy, using acridine orange, for the detection of residual basal cell carcinoma (BCC) in Mohs fresh tissue excisions. METHODS: Forty-eight discarded skin excisions were collected following completion of Mohs surgery, consisting of excisions with and without residual BCC of all major subtypes. The tissue was stained with acridine orange and imaged with a fluorescent confocal mosaicing microscope. Confocal mosaics were matched to the corresponding H&E stained Mohs frozen sections. Each mosaic was divided into subsections, resulting in 149 sub-mosaics for study. Two Mohs surgeons, who were blinded to the cases, independently assessed confocal sub-mosaics and recorded the presence or absence of BCC, location, and histologic subtype(s). Assessment of confocal mosaics was compared to corresponding Mohs surgery maps. RESULTS: The overall sensitivity and specificity of detecting residual BCC was 96.6% and 89.2%, respectively. The positive predictive value was 92.3% and the negative predictive value 94.7%. Very good correlation was observed between confocal mosaics and matched Mohs frozen sections for benign and malignant skin structures, overall tumor burden and location, and identification of all major histologic subtypes of BCC. CONCLUSIONS: Fluorescent confocal mosaicing microscopy using acridine orange enables detection of residual BCC of all subtypes in Mohs fresh tissue excisions with high accuracy. This observation is an important step towards the long-term clinical goal of using a non-invasive imaging modality for potential real-time surgical pathology-at-the-bedside for skin and other tissues.

5 Years review of periocular basal cell carcinoma and proposed follow-up protocol

“…Fluorescein confocal mosaicing microscopy 24 and multispectral polarized light imaging 25 show promising results but are still largely experimental.…”

Multimodal imaging to study the morphochemistry of basal cell carcinoma

“…If malignant cells are revealed at the surgical border further surgery is performed until a clean normal border is detected. During this procedure called Mohs surgery, which can be very devastating for the patient, a large skin area is excised [41]. The samples have been cut into 20 mm thick slices using a cryotome and mounted unfixed and unstained on glass slides.…”

Harnessing the Power of Light to See and Treat Breast Cancer

“…Various optical microscopy techniques including reflectance and fluorescence [12,17,18], Raman [19], confocal [20,21], and optical coherence tomography [22,23] have been used to exploit intrinsic sources of contrast in thick tissues. Additionally, fluorescence microscopy has been combined with vital fluorescent stains such as acridine orange (AO) [24][25][26], acriflavine [27,28], and DAPI [29] to visualize micro-anatomical features in skin [24], breast [29], ovarian [26], oral [27], and esophageal [28] cancers. All of these technologies enable rapid and completely non-destructive visualization of tissue histology.…”