Benign lesions such as melanocytic nevi (moles), skin tags, seborrheic keratoses, cherry angiomas, and epidermoid cysts are commonplace, and are consequences of the skin's normal hereditary, age-appropriate, maturation process.

Skin lesions—particularly pigmented skin lesions—often present a difficult and puzzling conundrum for the nondermatologist health care provider. Questions such as “Am I missing a melanoma?” “Is this mole suspicious?” and “Is this a skin cancer?” may arise. In reality, the answer is not always apparent. In fact, the decision of whether a lesion is benign or malignant is often a challenge for many dermatologists as well. Distinguishing between a benign pigmented lesion such as a melanocytic nevus or a seborrheic keratosis and a potentially fatal skin cancer such as a melanoma creates the most concern among health care providers.

As with most skin lesions, familiarity breeds recognition. This chapter, along with Chapter 31: Premalignant and Malignant Cutaneous Neoplasms, presents the various common benign and malignant neoplasms in their diverse clinical guises.