As dermatologists, we can screen for skin-cancer and precancerous lesions.

Actinic-keratosis - blotches on the skin caused by sun exposure - have the potential to become cancerous, and can be surgically excised.

If you are fair-skinned, and especially if you are of Northern European descent, you may have dysplastic nevi - multiple moles on your back, chest, and stomach - that are also predictive of skin-cancer later on. These should be monitored closely.

Basal cell and squamous cell carcinomas are common low-grade skin-cancers that are usually caused by sun exposure, and screening for them is important to your visit with the dermatologist. They are easily excised with such modern techniques as Mohs micrographic surgery.

Dark, blotchy skin lesions with irregular borders may be melanoma, and should be biopsied immediately.