An experienced doctor should first rule out noncancerous (benign) conditions that resemble melanoma, such as a mole called a melanocytic nevus.
In rare instances, a melanoma will be difficult to detect. For example, an uncommon form called a myxoid melanoma may be mistaken for a benign skin disorder known as a myxoid fibrohistiocytic lesion. Additional diagnotic procedures such as a biopsy (see below), computerized image processing or advanced staining techniques may help to confirm or rule out the diagnosis of melanoma.
Melanoma also tends to be diagnosed at a later stage in people with darker skin.
Dermoscopy and Total Body Photography
A combination of imaging approaches should be considered for early melanoma detection and diagnosis, since each technique alone has limitations. Some doctors now use various handheld scope-like devices (dermoscopy, dermatoscopy, or epiluminescence microscopy) that enhance the visualization of the suspected lesion.
A skin biopsy is the removal of skin tissue for examination under a microscope. The exact type of biopsy depends on how deep the lesion has penetrated the skin.
- Shave biopsy uses a thin surgical blade, or scalpel, to shave off the top layers of skin. The doctor may use this type of biopsy to diagnose basal cell cancer.
- Punch biopsy uses a round, cookie-cutter-like tool. It is used to take a deeper sample of the skin.
- Incisional and excisional biopsies remove tumors that have grown deep into the skin. An incisional biopsy cuts out part of the tumor. An excisional biopsy removes the entire tumor. These biopsies are used to diagnose melanoma.
All of the above-mentioned biopsies can be done using local anesthesia.
Lymph Node Biopsy
A lymph node biopsy may be needed for patients with recently diagnosed melanoma, to help determine whether the cancer has spread to one or more lymph nodes.
Review Date: 07/04/2010
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.