Confocal microscopy adjunct to diagnosing melanocytic lesions

August 1, 2005

Vienna, Austria — Confocal laser scanning microscopy (CLSM) is likely to become an adjunct to traditional forms of diagnosing melanocytic lesions, according to a presenter at the 10th World Congress of Cancers of the Skin.

Vienna, Austria - Confocal laser scanning microscopy (CLSM) is likely to become an adjunct to traditional forms of diagnosing melanocytic lesions, according to a presenter at the 10th World Congress of Cancers of the Skin.

"Confocal microscopy gives us cellular detail in vivo," says Dr. Ashfaq A. Marghoob, associate professor of dermatology at Memorial Sloan-Kettering Cancer Center and Stony Brook University. "Although routine histology will remain the gold standard, confocal is a tool that can provide information about the cellular structure of the skin and can be utilized when the clinical exam and dermoscopy are unable to provide a definitive answer."

Greater accuracy

However, the high sensitivity for detecting melanoma gained by short-term follow-up is contingent on the patient appearing for the follow-up appointment. Furthermore, it also means that some subtle melanomas may go undiagnosed for three to four months.

With confocal microscopy, clinicians and patients won't have to wonder whether a lesion is benign or malignant, since they will be able to see the cellular structure of the lesion and know the answer immediately, at the bedside, with a high degree of certainty.

Differentiation

Dr. Marghoob differentiated between the characteristics of normal features of nevi compared to malignant melanoma. Where normal nevi are small and regular, and have a regular clustering of cells that are round to oval in shape and have architectural order, malignant melanoma have disrupted cell borders; irregular, atypical shapes; elongated, thickened dendrites; a pagetoid distribution of cells; and architectural disarray.

In theory, the use of CLSM would save on the cost of performing biopsies and pathology step-sectioning, Dr. Marghoob tells Dermatology Times.

One of the areas where confocal microscopy can be useful is in establishing margins of excision when a skin cancer has to be surgically removed, Dr. Marghoob notes.

"It's often difficult to establish what the borders should be in lesions such as ill-defined lentigo maligna on the face," Dr. Marghoob says. "It's often impossible to decide with lentigo maligna, for instance, where the melanoma ends and normal skin begins. Consequently, surgeons have a difficult time deciding where to cut. Using confocal microscopy, you could map out the borders, so that when a patient undergoes surgery, you know where to cut. It would be a huge advantage to those patients because they can potentially have the melanoma excised in one stage without the need to undergo multiple excisions performed over many days."

Confocal microscopy can also be employed to check for amelanotic melanoma recurrence and to track lentigo melanoma that have been treated with topical agents such as imiquimod, according to Dr. Marghoob.

"With confocal microscopy, a recurrence could be detected much sooner than if the area was followed only clinically," he says.

He adds that a "learning evolution" is taking shape with confocal microscopy, similar to when dermoscopy began to be used in dermatological practice.

New paths

Moreover, the emergence of confocal microscopy is leading to new areas of research, such as fluorescent antibody tagging of target cells and dual-mode, fluorescent CLSM to assess neo-angiogenesis and melanoma, Dr. Marghoob notes.

At present, a handful of centers in the United States, one center in Canada and several centers in Europe use confocal microscopy. Given its high cost, the technology will likely be restricted to specialized centers in the near future, Dr. Marghoob says.