Page 26 - Noninvasive Diagnostic Techniques for the Detection of Skin Cancers

BCC, 5 on SCC, and 59 were combinations. Three non-randomized studies were identified in the
ClinicalTrials.gov registry (see Appendix C, Table C2).
The main topics covered in these abstracts were: (1) dermoscopic features including lesion
characterizations and histopathological correlations (94 abstracts); (2) general introduction and
how-to articles (71 abstracts); (3) digital dermoscopy including automation and computer
analysis (42 abstracts); (4) dermoscopy algorithms/image classification/checklist (39 abstracts);
(5) other aspects of digital dermoscopy including teletransmission of digital images (23
abstracts); (6) general diagnostic accuracy (24 abstracts); and (7) follow up studies to monitor the
change in pigmented lesions (15 abstracts); and (8) training (19 abstracts). No more than 6
percent of the total abstracts reported on the following: (1) other technical aspects of
dermoscopy; (2) guidelines or proposals; (3) dermoscopy in nonwhites; (4) pregnancy; (5) and
other miscellaneous variables. For the 15 abstracts that reported on longitudinal follow up
(ranged from 3 months to 4 years) using dermoscopy, the outcome of interest was mainly the
change in the number and the characteristics of pigmented lesions. No change in survival
outcome was reported.

Description of Technique
Dermoscopy (also known as surface microscopy or epiluminescent microscopy or
dermatoscopy) provides at least a 10-fold magnification of skin lesions by using either
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nonpolarized or polarized light. There is generally good agreement for overall dermoscopic
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patterns between polarized and nonpolarized dermoscopy (kappa 0.88 to 1.00). Differences
between the two are detailed below. Dermoscopy is used to differentiate between benign and
malignant pigmented skin lesions, and aids in the overall assessment of pigmented lesion
morphology. Types of dermoscopy devices are as follows:
• Nonpolarized light contact dermoscopy. 14,16,52-54 This device uses a nonpolarized light
source (a halogen light source at a 45° angle), and requires the use of an oil or gel
interface on the lesion to prevent surface reflection. It provides better illumination and
resolution than polarized dermoscopy. The colors of lesions appear sharper in
nonpolarized dermoscopy compared with polarized dermoscopy; the former is therefore
useful in visualizing milia-like cysts and comdeo-like openings, peppering, lighter colors,
and blue-light areas. Its cost is approximately $150.00.
• Polarized contact/noncontact dermoscopy. 14,16,52-54 Polarized dermoscopy devices do not
need a liquid interface and are equipped with a cross-polarized lens that absorbs scattered
light waves. Polarized contact dermoscopy can attain the images of vascular and other
deeper structures, and is a useful tool in visualizing melanin, blue nevi, and shiny white
streaks. Polarized noncontact dermoscopy is better used for imaging mucous membranes.
Since direct skin contact is not required for visualization, the use of noncontact
dermoscopy minimizes the risk of nosocomial infection. These devices (contact or
noncontact) cost approximately $300.00 or more.
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• Combined polarized and nonpolarized dermoscopy. These devices incorporate the
desirable characteristics of both types of dermoscopy. Clinicians can choose to use either
polarized or nonpolarized lights. Its cost is approximately $1200.00.

Theoretical Advantages
Because of its ability to magnify lesions and reveal subsurface structures, dermoscopy is
expected to have higher sensitivity and specificity than the naked eye in detecting malignancies,

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