They could be the result of overproduction of melanocytes, cells in your skin responsible for "darkening" when stimulated by sunlight, though sometimes they over-produce melanin on their own. You can ask a dermatologist for a spot lightening treatment by laser or ask for a lightening cream that you would use on those spots. Over the counter products that take much longer (DDF makes a new pod spot treatment with niacinamide) are also options.
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