Diagnosis

The two most commonly used diagnostic tools are:

• A dermatoscope.

• A modern polarized dermatoscope.

Clinical diagnosis is made with visual appearance or with the aid of a dermatoscope. The ABCD guideline is helpful for identifying dysplastic nevus and melanoma.

Clinical diagnosis can only be confirmed with a skin biopsy. Most skin biopsies are done under local anesthetic with an injection.

• A shave biopsy is good for diagnosing basal cell carcinoma, while not as well for squamous cell carcinoma.
• A punch biopsy is preferred for diagnosing squamous cell carcinoma and melanoma over the shave biopsy technique.
• Excisional biopsy (where the entire lesion is removed down to the deep dermis and subcutanous fat) is the method of choice for diagnosing melanomas.
• However, for cosmetic reason and practical reasons, a punch biopsy is often used to initially diagnose many large melanomas or melanomas of cosmetically important anatomic locations (nose, face, eyelids, nails, fingers and toes).