Diagnosis

Diagnosis

An experienced doctor should first rule out benign conditions that resemble melanoma, such as a noncancerous mole called a melanocytic nevi. In rare instances, a melanoma will be difficult to detect. For example, an uncommon form of melanomas called a myxoid melanoma may be mistaken for a benign skin disorder known as a myxoid fibrohistiocytic lesion. Another opinion from a second pathologist, computerized image processing, or advanced staining techniques may help to confirm the diagnosis.

Some doctors now employ dermoscopy (also called dermatoscopy or epiluminescence microscopy), which uses a hand-held scope-like device that enhances the suspected lesion. It is still not clear if such devices are any better than the naked eye of a trained professional. Of interest, however, was a 2002 study suggesting that it was very useful in identifying possible melanomas in suspicious nail abnormalities and therefore avoiding many painful biopsies in this area. A 2004 study confirmed that adding dermoscopy to conventional naked-eye examination leads to fewer biopsies than using naked-eye examination alone.

A recently developed Australian device (the Solarscan) may improve detection. It is shaped like a hair dryer and takes an image of the suspicious lesion; it then reads the image and compares it with a databank of melanoma images to help determine if it is cancerous. It can also store the image of the lesion and compare it for changes with later images taken at subsequent check ups.

Biopsy

Biopsy of the Melanoma. Melanoma is diagnosed by biopsy (excision) of suspicious lesions. With this procedure, the doctor will anesthetize the area around the lesion and, depending on size and site, remove all or part of it. The biopsy specimen will be sent to a lab for analysis, where a pathologist will take thin slices of the lesion and examine the cell structure under a microscope. If melanoma is found, it will be staged and its depth and probability of spreading will be assessed.

• Melanomas less than 4 mm thick suggest Stage I or II cancers, and the next step is to attempt to determine if they have spread or are likely to spread to the lymph nodes.
• Melanomas that are over 4 mm thick indicated later stages. In such cases, the lymph nodes are sometimes removed to attempt to prevent the cancer from spreading, although about 70% of these melanomas have already metastasized (spread).