Ex vivo fluorescence confocal microscopy for fast evaluation of tumour margins during Mohs surgery

Authors

  • A. Bennàssar,

    Corresponding author
    1. Melanoma Unit, Dermatology Department, Hospital Clínic & IDIBAPS (Institut d'Investigacions Biomèdiques Agustí Pi i Sunyer), Barcelona, Spain
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  • A. Vilata,

    1. Melanoma Unit, Dermatology Department, Hospital Clínic & IDIBAPS (Institut d'Investigacions Biomèdiques Agustí Pi i Sunyer), Barcelona, Spain
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  • S. Puig,

    1. Melanoma Unit, Dermatology Department, Hospital Clínic & IDIBAPS (Institut d'Investigacions Biomèdiques Agustí Pi i Sunyer), Barcelona, Spain
    2. Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Barcelona, Spain
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  • J. Malvehy

    1. Melanoma Unit, Dermatology Department, Hospital Clínic & IDIBAPS (Institut d'Investigacions Biomèdiques Agustí Pi i Sunyer), Barcelona, Spain
    2. Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Barcelona, Spain
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  • Funding sources This project has been supported by personal grants to A.B. from Hospital Clínic de Barcelona ‘Emili Letang’ and is partially supported by Fondo de Investigaciones Sanitarias (FIS) grant 09/1393; CIBERER U-726, ISCIII.
  • Conflicts of interest The Vivascope® 2500 was borrowed from Lucid Inc. for 8 months (now Caliber Imaging and Diagnostics).

Summary

Background

Ex vivo fluorescence confocal microscopy (FCM) enables real-time imaging of skin morphology directly in freshly excised tissue. FCM displays wide field-of-view mosaics with cellular resolution, thus enabling a rapid bedside pathology. An application of interest is rapid detection of residual basal cell carcinoma (BCC) in skin excisions during Mohs surgery.

Objectives

We sought to evaluate the sensitivity and specificity of ex vivo imaging with FCM for the detection of residual BCC in Mohs tissue excisions, and to calculate the time invested up to the diagnosis for both FCM and frozen sections.

Methods

Eighty consecutive BCCs were prospectively collected and the margins scanned with ex vivo FCM, including excisions with and without residual BCC of all major subtypes. Each mosaic was divided into two or four, resulting in 480 submosaics for study. Every confocal submosaic was assessed for the presence or absence of BCC and compared with standard frozen sections as the gold standard. Furthermore, the time spent for each technique was calculated and compared.

Results

The overall sensitivity and specificity of detecting residual BCC were 88% and 99%, respectively. Moreover, the new technique reduced by almost two-thirds the time invested when compared with the processing of a frozen section (< 0·001).

Conclusions

The results demonstrate the feasibility of confocal mosaicing microscopy in fresh tissue for rapid surgical pathology, potentially to expedite and guide Mohs surgery with high accuracy. This observation is an important step towards the goal of using real-time surgical pathology for skin tumours.

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