Laser scanning microscopy

Vienna, Austria - Confocal laser scanning microscopy (CLSM) will improve diagnosis of lesions to rule out which lesions are benign and not cause for concern, according to a presenter here at the 10^th World Congress of Cancers of the Skin.

"We want to be able to differentiate between benign and malignant lesions," said Dr. Stefania Seidenari, M.D., professor of dermatology at the University of Modena in Modena, Italy. "This is a non-invasive technique which allows you to explore horizontal planes of the skin. The characteristics of the lesions in the epidermis and the upper epidermis can be better distinguished using confocal laser scanning microscopy. With this technique, we can anticipate the results that we find with histopathology."

How it works

The microscope allows instantaneous, high-resolution images of the cells without damaging the skin. Since melanin represents a strong source of contrast, CLSM is suitable for the study of lesions containing melanin (nevi and melanomas), and may, in the future, avoid unnecessary excisions of benign melanocytic lesions and definitively diagnose melanoma.

Dr. Seidenari and her colleagues published three studies in the last year on the benefits of CLSM. One of their studies, which was published in Modern Pathology, looked at 55 melanocytic lesions made up of 20 melanomas, 25 acquired nevi, and 10 Spitz nevi, all of which were studied by confocal microscopy, dermoscopy and traditional histopathology. The samples came from a database of 89 melanocytic lesions. The melanomas that were studied had a mean Breslow thickness of 0.81 mm.

Researchers established three different types of cell clusters, those being dense, sparse cell and cerebriform clusters, and were matched against histopathological examination. Sparse cell clusters appeared more frequently in melanomas, but also appeared in one Spitz nevus. Cerebriform clusters were observed in five out of 20 melanomas.

In addition, the study showed the presence of cell clusters forming nests in melanomas and Spitz nevi, which had not been previously reported. The presence of cell clusters forming nests had been reported in melanocytic nevi and in lentigo maligna.

Another study that Dr. Seidenari and her colleagues published appeared in the Journal of the American Academy of Dermatology late last December. It found a close correlation between confocal scanning laser microscopy, epiluminescence and histopathologic aspects in evaluating Spitz nevi, or benign melanocytic lesions sometimes mistaken for melanoma. That study looked at six Spitz nevi in patients whose average age was 29.8. The nevi were symmetric lesions ranging in diameter from 4 to 8 mm. Researchers used a specific software to reconstruct CLSM images.

Still another study published in the Archives of Dermatology in February 2005 compared 15 confocal images, 15 dermoscopic atypical nevi and 15 common nevi. Researchers focused on features such as size, regularity, homogeneity and infiltration of dermal papillae. In analyzing the cytologic features through CLSM, melanomas were characterized as larger and more irregular cells compared with acquired nevi.

Not a replacement

Dr. Seidenari notes that CLSM would not replace the gold standard in diagnosing lesions, which is histology or the clinical exam, but can add valuable information in a preoperative stage and possibly modify the surgical strategy by improving the pre-operative diagnostic accuracy.

"We can recognize the architecture of the skin," Dr. Seidenari says. "We also see the morphology of the cells. Confocal microscopy can be more sensitive than dermoscopy. The particular advantage is that confocal microscopy offers practically in vivo histology."