Confocal microscopy: Technology expands visual horizons of dermatologists

Key Points

Buenos Aires, Argentina - Early detection can oftentimes be critical in a positive prognosis of skin cancer patients, and, therefore, dermatologists are very careful to make a correct and timely diagnosis in their patients.

Statistics show that a dermatologist's sensitivity in detecting melanoma by visual clinical examination is in the range of 65 to 80 percent.

"Right now, we primarily rely on visual inspection.

Dr. Halpern says a new technology, Reflectance Confocal Microscopy (RCM), is one diagnostic tool with significant promise to help dermatologists in determining if a given skin lesion is benign or malignant.

However, according to Dr. Halpern, confocal microscopy is not yet ready for clinical practice.

Adjunct uses

It is a new technology that is under clinical evaluation as a potential adjunct.

Even so, some dermatologists are beginning to use this diagnostic method as an adjunct both in the diagnosis and management of skin lesions.

"Confocal microscopy may not only be useful for pigmented lesions, because it is a general, noninvasive, quasi-histological imaging technology.

"It may have as much - if not greater - use in nonmelanoma skin cancer and other areas of dermatology," Dr. Halpern tells Dermatology Times.

In ongoing experiments with RCM, Dr. Halpern has shown that there is a fairly good correlation between what can be seen noninvasively down to the papillary or superficial dermis using this instrument and what is seen histologically on biopsy specimens.

He says these images correlate quite well, albeit imperfectly, especially in pigmented lesions where the melanin and the melanosomes serve as a very strong endogenous contrast agent.

Dr. Halpern says that a more recently published trial with the RCM by Giovanni Pellacani, M.D., and colleagues (J Invest Dermatol. 2007 Dec;127(12):2759-2765. Epub 2007 Jul 26) has shown that this novel technology can help in the accurate diagnosis of equivocal melanocytic lesions above and beyond visual examination and dermoscopy.

Further, according to Dr. Halpern, confocal microscopy also has the potential to improve the assessment of lateral tumor margins prior to surgery for both melanocytic and non-melanocytic skin malignancies.

Limitations

"It cannot replace Mohs surgery, because one of the limitations of confocal microscopy is that it only images very superficially within the skin, namely to the papillary dermis.

"What it cannot tell you are the deep margins, nor will it.

"There are other imaging technologies that are able to image deeper into the skin - but there is currently no imaging technology that can image more deeply and provide cellular resolution," Dr. Halpern says.

Mohs surgery

Confocal microscopy can support Mohs surgery in two ways.

One way is by pre-surgically determining the lateral margins.

The other way it can potentially support Mohs surgery is by replacing the intra-operatively frozen sectioning currently being done.

So, rather than having to process and examine individual microscopic sections, one could theoretically examine the entire undersurface of the removed specimen with the confocal microscope.

Dr. Halpern says this would save a considerable amount of time, tissue processing and, possibly, money.

The future

"Dermatologists will, over time, incorporate new diagnostic technologies into their practice, as have all other specialties.

"Among those potential technologies, confocal microscopy has several promising features - most importantly, that it delivers very high resolution and the ability to visualize individual cells, albeit only in superficial layers of the skin," Dr. Halpern says.