Chloasma often occurs on the face. If chloasma-like lesions appear on the arms, it may be the lesion manifestation of senile freckles, reticular telangiectasia or café au lait spots. 1. Age-related freckle: it often occurs in middle-aged and old people over 40 to 50 years old, and it may appear as dark brown spots with uniform pigmentation on exposed parts of sunburners such as forearms, back of hands, forehead, etc., which may gradually become bigger and bigger and merge into pigmented spots. 2. Reticular limb hyperpigmentation disease: it can be related to genetic factors, with the appearance of rice grain to bean grain size reticular brown spots on the forearms, back of hands, calves, etc. The color of the lesions can be darkened due to sun exposure. 3. Coffee spot: congenital uniform color patches, lesions border clear, size and number of indeterminate, can be located in any part of the body, does not naturally disappear and malignant changes, yellow-brown patches or freckle-like dots appear on the skin. The appearance of yellow-brown spots on the arm can be consulted for treatment measures, and usually avoid prolonged sun exposure.