In vivo reflectance confocal microscopy of shave biopsy wounds: feasibility of intraoperative mapping of cancer margins

Background Reflectance confocal microscopy (RCM) images skin at cellular resolution

and has shown utility for the diagnosis of nonmelanoma skin cancer in vivo.

Topical application of aluminium chloride (AlCl3) enhances contrast in RCM

images by brightening nuclei.

Objectives To investigate feasibility of RCM imaging of shave biopsy wounds using

AlCl3 as a contrast agent.

Methods AlCl3 staining was optimized, in terms of concentration vs. immersion

time, on excised tissue ex vivo. RCM imaging protocol was tested in patients

undergoing shave biopsies. The RCM images were retrospectively analysed and

compared with the corresponding histopathology.

Results For 35% AlCl3, routinely used for haemostasis in clinic, minimum immersion

time was determined to be 1 min. We identified three consistent patterns of

margins on RCM mosaic images by varying depth: epidermal margins, peripheral

dermal margins, and deep dermal margins. Tumour islands of basal cell

carcinoma were identified at peripheral or deep dermal margins, correlating on

histopathology with aggregates of neoplastic basaloid cells. Atypical cobblestone

or honeycomb patterns were identified at the epidermal margins in squamous

cell carcinomas, correlating with a proliferation of atypical keratinocytes extending

to biopsy margins.