What is the role of lab testing in the diagnosis of polymorphous light eruption (PMLE)?

Updated: Jan 22, 2020
  • Author: Saud A Alobaida, MBBS, FRCPC; Chief Editor: Dirk M Elston, MD  more...
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In polymorphous light eruption (PMLE), laboratory tests can be performed to rule out other dermatoses such as erythropoietic protoporphyria or lupus erythematosus. Antinuclear antibody (ANA), anti-Ro (SS-A), and anti-La (SS-B) tests, as well as urine, stool, and blood porphyrin levels, should be obtained when clinically indicated. [43]

Normal titers of ANA, as well as normal urine, stool, and blood porphyrin levels, support the diagnosis. A false-positive ANA can be seen, as a titer of 1:80 has been reported in up to 13% of normal population.

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