Sun allergy types -- trying to diagnose life-long sun reaction

[danholme]

Since I was a child, I have had a reaction to the sun that happens only in certain locales (closer to the equator).  After 3-4 days, my hands & fingers begin to swell then I begin to break out.  Always on the back of my hands -- occasionally on elbows and knees.  Looks like little blisters -- definitely filled with fluid.  Blisters cover most of back of hand.  This time (Costa Rica) very big blisters on hands as well.  Extremely itchy.  Always goes away with no apparent permanent damage, but always ruins days 5 - 12 of any tropical travel.

Because of the number of times I've had this over my life (I'm 35 now, and male btw), it is safe to say there is no apparent pattern that would indicate a photosensitive reaction from any one chemical (e.g. no deodarants as a child; different sunblocks over my life -- most or all without PABA).  

Amount of sun exposure, or location of sun exposure, doesn't seem to be an issue.  While my hands are always exposed, elbows and knees are not, particularly.  It's almost as if the rxn is just manifesting in those locations.  This time, I had VERY little sun exposure (I was in the rain & cloud forest for the first days of this trip) and the reaction was much worse than usual, though I was on zithromycin which could have increased photosensitivity.

As a child, a doctor told me I was allergic to wavelengths of UV that only exist between certain latitudes, which seems to fit.  I think I've had it happen in the continental US only 1 or 2 times in my life.

I always take antihistamine (Claritin) and corticosteroid cream (1%) which don't seem to help much but I don't want to test that theory by stopping :-)

What I'm trying to determine is what is going on.  I have found out about photosensitivities, sun allergies, PMLE (or PLE), solar uticaria, and lupus enough to know that all could be the issue, but I'm not clear as to what the DISTINGUISHING SYMPTOMS are, or which I can rule out based on my history.  My primary care & dermatologists over the years haven't been too helpful... Maybe I need to go back to Hawaii and find some DO's there that know about sun allergies in those regions ;-) ...

I appreciate your insight!!!

[Oscar A. LeBron]

A few years ago, I began to develope a rash that began around my ankles and then it proceeded up my legs and around my torso. At first I thought it was just ordinary heat rash. But I became concerned when it continued up my legs. This would take a couple of weeks to occur. At one time it would go away on its own. However, this year, it has come back with a vengence. The rash, again, began around my ankles, from there, it proceeded up my legs,thighs, hips, torso, arms, neck, and head. Fortunately, it is not so bad around my head, But, my legs, and thighs are very bad. Itching, at times, can be intense. Even to the point of burning. I have tried different forms of over the counter medication, and a prescription one called Hydroxyzine. Nothing seems to help. I have even began to use alchohol and ice just to numb the itching. It would work for a time. But, now I have all these pimple like blisters, that once they dry, they develope scaring. I am scheduled to see my health provider to see if he can refer me to an excellent dermotologist. These pimple like blisters sometimes appear in clusters and no bigger than a pimple or a mosquitoe bite. Any suggestions?

[Cpt Kelp]

Just by chance, are you taking Doxycillan as an antimalarial when in the tropics acting to induce (as mentioned potential) photosensitivity?

[Alan Rockoff, MD]

Your story seems to fit PMLE best.  That acronym refers to polymorphous light eruption, a presumed allergy to the long waves of ultraviolet light (UVA).  In most cases the cause is unknown.  Lupus is unlikely but should be ruled out by blood tests (perhaps these were already done.)  The condition tends to affect the upper chest and armas rather than the face, though patterns differ.  Like you, many patients have told me that they only get it in tropical climes, not in the US, even when sun is intense.  I don't know how to explain this.

Treatment is avoidance (not what people want to hear.)  Pretreatment with antihistamines (like Claritin), use of UVA-blocking sunscreens (there are many on the market), and covering up as much as possible all help to some extent.

I suggest you consult another dermatologist (perhaps with good photos in tow, in case the rash is not there when you go).  Sophistcated phototesting to determine the precise wavelength you're allergic to is done at some major medical centers.  That may be something worth looking into as well.

Best.

Dr. Rockoff