Disorder	Appearance	Age of onset	Hormone or medication related	Sun or otherexposure involved	Associated systemic complications	Treatment
Acanthosis nigricans	Velvety brown color, located in axillae, on neck, and in areas of skin folds	Adolescence to adulthood	Insulin resistance	Not involved	Increased risk of diabetes, polycystic ovary syndrome, dyslipidemia and, possibly, underlying malignancy	Treat underlying disease or condition.
	With acute onset (especially on palms or soles) in nonobese adults, evaluate carefully for malignancy.
Melasma	Macular hyperpigmentation of cheeks, forehead, and upper lip	Adulthood	Pregnancy, use of oral contraceptive pills, phenytoin (Dilantin) therapy	Increased by sun exposure	None	Treat for cosmesis avoid sun exposure; use bleaching laser therapy, ordermabrasion.
Diabetic dermopathy	Papular pink or brown eruption evolving to macular, sometimes confluent brown eruption on anterior shins	Adulthood	Uncertain	Not involved	Multiorgan dysfunction related to underlying diabetes	Treat underlying diabetes.
Tinea versicolor	Dark or light scaly lesions, single or confluent patches on trunk	Adolescence through adulthood	Increased sebum production starting in adolescence	Hypopigmented appearance because tanning process is blocked	None	Treat with topical selenium sulfide shampoo, or topical or oral antifungal agents.
Postinflammatory hyperpigmentation	Localized, macular, brown hyperpigmentation at site of inflammation	Any age	Not related	Reaction to trauma (physical or chemical injury), skin irritation, or dermatoses	Inflammation of skin because of underlying injury or condition	Refer patient to cosmetic dermatologist.