Page 31 - Noninvasive Diagnostic Techniques for the Detection of Skin Cancers

Devices in Limited Clinical Use

The devices described in this section include those that are not in general use, those for
which we were unable to identify any RCTs to evaluate patient or health outcomes, or those for
which we found no evidence of FDA approval/clearance for use in the evaluation of suspicious
skin lesions. Some of these technologies have been used in other clinical context over several
years (e.g., ultrasound and photodynamic diagnosis). Recent modifications increase their
potential (or future) application to skin cancer detection.

Confocal Microscopy

Confocal scanning laser microscopy (CSLM) aids in the evaluation of skin lesions by
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providing high resolution skin tissue images that are similar to histopathological images. This
technique works by first projecting a low-power laser beam through a lens on a specific point on
the skin, and then detecting the light reflected from the focal point through a confocal pinhole
filter. The reflected light is transformed into an electrical signal, which is recorded as an image
by a computer. 79-81 Although there is some variability by manufacturer, these devices allow the
user to evaluate the lesion at the cellular level.

Available Literature
®
Our systematic literature search of MEDLINE identified 72 abstracts relevant to confocal
microscopy from the following types of studies: 17 narrative reviews, 12 technical reports, 7
diagnostic tests, 6 comparative cohorts, 26 noncomparative cohorts, and 4 case reports (see
Appendix D, Table D1). Reported clinical settings included 14 dermatology, 2 primary care, and
1 oncology practice. Identified studies addressed the use of confocal microscopy in patients with
suspected melanoma (n=29, 40.2%) and NMSC (n=15, 20.8%). Several studies (n=28, 39%)
addressed its use in a combination of skin cancer types. (See Appendix D, Table D2) The most
commonly reported outcome was lesion characterization (27 studies), followed by test accuracy
(17 studies) (see Appendix D, Table D4). No clinical outcomes were identified.
We identified eight observational studies of confocal microscopy on the ClinicalTrials.gov
registry (see Appendix C, Table C2). Five of these studies specified the use of reflectance
confocal microscopy; the rest did not specify the type of technique. Although three studies were
completed and one was suspended, results for these studies were not posted.
Topics covered in these abstracts included: (1) features of microscopic images
histopathological correlates (36 abstracts); (2) general overview of the technology and its use (20
abstracts); (3) test accuracy including sensitivity and specificity data (10 abstracts); (4) technical
report and glossary (3 abstracts); (5) diagnostic algorithms and automation (2 abstracts); and
(6) other 2 abstracts). Out of the 36 studies that reported features of images and histopathological
correlates, only 6 studies had more than 100 participants. All 10 studies that provided test
accuracy data were done out of the US (6 in Austria, 1 in Australia, 1 in Germany, 1 in England,
1 in Sweden).

Description of Technique
Resolution of CSLM images is specific to each device, and is determined by the wavelength
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of the laser beam, the topical aperture of the lens, and the size of the pinhole. The maximum
depth of imaging is 350 µm. The uniqueness of CSLM lies in its imaging of not only the
epidermis, but also underlying structures and the papillary dermis. With its high resolution,

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