Confocal mosaicing microscopy in skin excisions: a demonstration of rapid surgical pathology

Precise micro-surgical removal of tumour with minimal

damage to the surrounding normal tissue requires a series

of excisions, each guided by an examination of frozen histology

of the previous. An example is Mohs surgery for

the removal of basal cell carcinomas (BCCs) in skin. The

preparation of frozen histology is labour-intensive and slow.

Confocal microscopy may enable rapid detection of tumours

directly in surgical excisions with minimal need for frozen

histology. Mosaicing of images enables observation of nuclear

and cellular morphology in large areas of surgically excised

tissue. In skin, the use of 10–1% acetic acid as a reflectance

contrast agent brightens nuclei in 0.5–5 min and enhances

nuclear-to-dermis contrast and detectability of BCCs. A

tissue fixture was engineered for precisely mounting surgical

excisions to enable mosaicing of 36 °— 36 images to create a

field of view of 12 °— 12 mm. This large field of view displays

the excision at 2°— magnification, similar to that routinely

used by Mohs surgeons when examining frozen histology.

Comparison of mosaics tohistology demonstrates detectability

of BCCs. Confocalmosaicing presently requires 9min, instead

of 20–45 min per excision for preparing frozen histology, and

thus may provide a means for rapid pathology-at-the-bedside

to expedite and guide surgery.