Hello,
Thanks for posting your query.
I can understand your concern for the skin rash on exposure to sun. From the symptoms two possibilities can be there.
These two possibilities are:
1) PLE: The first possibility is of course polymorphous light eruption(PLE) as you are suspecting. The exact cause of polymorphous light eruption isn't well-understood but in this some people may develop sensitivity to components of sunlight especially UV radiation of sun. Diagnosis can be confirmed by phototesting in which small areas of your skin are exposed to measured amounts of UVA and UVB light to try to reproduce the problem. If your skin reacts to the UV radiation, you're considered sensitive to sunlight (photosensitive) and may be having PLE. Your dermatologist may also do a skin biopsy to confirm the diagnosis.
2) Second possibility is of solar urticaria which cause appearance of itchy hives in both covered and uncovered areas of the skin on exposure to UV light of sun or even visible light. Generally, the areas affected are exposed skin not usually protected by clothing; however it can also occur in areas covered by clothing. Diagnosis can be confirmed by phototesting which includes photopatch tests, phototests, photoprovocation tests, and laboratory tests.
Treatment of PLE mainly consists of antihistamines and phototherapy. Another way to prevent severe PLE is to undergo a course of desensitization treatment. For solar urticaria, the treatment consists of antihistamines, desensitization, immunosupression and plasmapheresis.
To confirm the diagnosis get it evaluated from a dermatologist as treatment is diagnosis specific.
Hope that this information helps and hope that you get better soon.
Wishing you good health.
Don't know if it makes a difference, but I am a DES baby.