Overview Freckle Caused by normal number of melanocytes but increased melanin within basal keratinocytes Darkens with sun exposure Lentigo Pigmented macule caused by melanocyte hyperplasia Does not darken with sun exposure Common mole A benign tumor derived from melanocytes Blue nevus Form of common mole, a benign tumor derived from melanocytes Black and blue nodule usually present at birth Often mistaken for melanoma Spitz nevus Form of common mole, a benign tumor derived from melanocytes Red-pink nodule Often seen in children Confused with hemangioma Dysplastic nevus Atypical, irregularly pigmented lesion Increased risk of transformation into malignant melanoma Dysplastic nevus synrome Autosomal dominant inherited disease Melasma Mask-like hyperpigmentation seen in pregnancy on the face Sunlight accentuates, so avoid sunlight Treat with hydroquinone cream Usually fades postpartum Xanthoma Yellowish papules Often accumulations of histiocytes Can be idiopathic or associated with hyperlipidemia Called xanthelasma when on eyelids Treat by decreasing lipidemia Surgically excise as needed Acanthosis nigricans Black, velvety plaques on flexor surfaces Seen in obesity and endocrine disorders Can mark underlying malignancy Seborrheic keratosis Black or brown benign plaques Appear to be stuck on skin "Coin lesions" Commonly seen in the elderly Runs in families Can be mistaken for melanoma Liquid nitrogen freezing, if not too many