Advances in melanoma diagnosis

January 19, 2009

Kohala Coast, HI - According to Darrell Rigel, M.D., current figures indicate that one in five Americans will be diagnosed with skin cancer in their lifetimes. And this number is expected to rise, he said, speaking at the Winter Clinical Dermatology Conference.

Kohala Coast, HI

- According to Darrell Rigel, M.D., current figures indicate that one in five Americans will be diagnosed with skin cancer in their lifetimes. And this number is expected to rise, he said, speaking at the Winter Clinical Dermatology Conference.

In 2006, 7,910 Americans died from malignant melanoma (MM). In 2007, 8,110 Americans died from the disease, and in 2008, MM resulted in 8,420 American deaths. These numbers indicate that one American dies every hour from the disease, Dr. Rigel said, but early detection can improve these statistics moving forward.

In the 1960s and 1970s, melanoma diagnosis relied on the presence of visible symptoms, such as bleeding. In the 1980s, diagnosis relied on the observation of clinical factors, including the asymmetry, irregularity, color and diameter of moles. In the 1990s, diagnosis advanced to include reliance on subsurface features through the use of epiluminescence microscopy. Today, dermatologists can rely on infrared technology to assist in their diagnoses of MM.

Dr. Rigel highlighted the MelaFind system (Electro-Optical Sciences), which uses 10 light bands (blue to infrared) to assist in the detection of MM. Shorter wavelengths don’t penetrate the skin as deeply and longer wavelengths do, providing the physician with the ability to analyze multiple depths and ultimately 500 characteristics per wavelength.

In one study, multispectral digital dermoscopy enabling automatic differentiation between MM and melanocytic nevi resulted in 246 lesions being categorized as either MM (63) or banal (183). After confirmation of diagnoses through biopsies and histopathology, the study concluded that 100 percent of the lesions were correctly diagnosed for sensitivity and 85 percent were correctly diagnosed for specificity.

Inclusion of lesion features derived from near infrared images can improve differentiation over that obtained with images in the visible region alone, Dr. Rigel said. In essence, this technology can provide the physician with an objective "second opinion."

According to a reader study published in May 2008 in the Archives of Dermatology, nine out of nine experts recommended a biopsy for a 43-year-old woman presenting with a lesion on her front thigh. MelaFind recommended no biopsy, and pathology results reported that the lesion was a low-grade nevus and not MM.

Another reader study involved a lesion on the foot of a 13-year-old boy. Nine out of nine experts recommended no biopsy, yet MelaFind recommended biopsy. Pathology results reported a melanoma in situ.

Another technology, confocal laser scanning microscopy, involves optical sectioning of a lesion. The technology takes approximately 10 to 15 minutes to analyze one image, Dr. Rigel said, and it continues to gain popularity as an effective adjunct to diagnosis of MM.

Ultimately, Dr. Rigel recommends using two or more technologies together to accurately diagnose MM. While confocal laser scanning microscopy appears to have a slighter higher sensitivity than dermoscopy, specificity is similar with both technologies. In effect, the procedures are complementary, Dr. Rigel said.

As an example of the accuracy that can be achieved using these complementary technologies, Dr. Rigel highlighted one study in which 125 patients with suspicious pigmented lesions were evaluated using both dermoscopy and confocal laser scanning microscopy. In the study, 88 melanocytic nevi and 37 melanomas were identified. After lesion diagnosis was confirmed by pathology, it was determined that not one melanoma was misidentified. DT