Diagnosis
Your dermatologist or other healthcare provider will examine your skin to diagnose melasma. They’ll use a Wood’s lamp (a black light) to see changes in the color of your skin. You might have your thyroid checked because there does seem to be an association between thyroid disease and melasma.
Melasma can sometimes be mistaken for another skin condition. To tell the difference between skin conditions, your healthcare provider may perform a biopsy, which is where a small piece of your skin is removed and examined. A biopsy is quick, safe procedure routinely performed during a normal visit to your healthcare provider’s office. Skin conditions commonly confused with melasma include:
Actinic lichen planus and lichen planus.
Drug-induced pigmentation.
Guttate hypomelanosis.
Hydroquinone-induced exogenous ochronosis.
Lentigo (age spots).
Nevus of Hori.
Nevus of Ota.
Postinflammatory pigmentation.
If you have melasma, the results of the biopsy will typically reveal the following:
Dendritic (branched) pigmented melanocytes.
Melanin in the basal and suprabasal keratinocytes.
Melanin in the dermis within melanophages.
Solar elastosis and elastic fiber fragmentation.