Investigations
1st investigations to order
Wood lamp examination
Test
Can be helpful in choosing a treatment modality, as epidermal melasma is more likely to respond to topical therapy, whereas dermal melasma is more likely to require laser treatments.
Result
melasma that accentuates with Wood lamp examination is generally more epidermal in location, whereas melasma that does not accentuate is more likely to be dermal in location
Investigations to consider
skin biopsy
Test
Done only if the clinical examination suggests another diagnosis, such as post-inflammatory hyperpigmentation or hyperpigmentation due to drugs or to exogenous ochronosis.
Result
lack of inflammatory infiltrate, epidermal hyperpigmentation, and melanin-laden macrophages in the dermis
Emerging tests
reflectance confocal microscopy (RCM)
Test
A tool that may be considered for the classification of melasma in the future.
Using melanin and melanosomes as contrast for RCM images, the technique is able to identify histological changes associated with melasma.
Allows for semi-quantification of the amount of pigment in each layer of the skin and can be used to classify the histological type of melasma without the need for an invasive procedure such as a skin biopsy.[19] One case report reported on the successful use of RCM to assess melasma in 20 female patients at baseline and 3-month follow-up after treatment.[20]
Result
amount of pigment in each layer of the skin; histological type of melasma
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