unknown skin discoloration

[socal_girl]

For the last 10 months, I have had a quarter-size discoloration on my upper/inner arm.  When it first appeared, I just thought it was a bruise, but then it never went away.  A few times now (once every few months) the area gets really itchy, red and swollen.  I saw a dermatologist who told me it was phytodermatitis and gave me tri-luma cream to bring the pigment back to normal.  I have experienced phytodermatitis before and it doens't seem consistent with what I'm experiencing now.  I don't understand what  make certain symptoms come and go, or what else could be causing this type of reaction. If you have any suggestions, I would greatly appreciate it!

[socal_girl]

Thanks for the quick reply... the discoloration literally started out looking like a faint bruise, except that it never hurt or had any sensation at all.  This persisted for months with the same appearance, when one day the entire area of the lesion swelled up from the surface of my skin and was very itchy/irritated feeling.  While the irritation lasted, the lesion also took on a more red color and the area of discoloration was a little larger.  After a couple of days, the spot returned to how it had looked before, like a purple/brown bruise.  This period of irritation has occured maybe three or four times.  Once the whole area got very irritated (probably from my itching it in my sleep) and actually scabbed over and peeled off.  The layer of skin underneath after healing also had the same discoloration.  
    Just last week the lesion again was swollen, I could just feel the itchiness and discomfort as soon as I woke up one morning.  When it is irritated, it is fairly unpleasant and uncomfortable.  To the best of my knowledge I can't correlate this reaction with anything else going on.  At first I thought maybe it was insect related but there does not appear to be any sting/bite site of any kind.  
    I'm not sure what other information I can give at this time.  It is not a perfectly round lesion, but circular in shape.  It also has a layer of surface skin peeling, but it may be from the tri-luma cream.  

[BhumikaMD]

Hi,

The information that you provided is brief, please describe in more details and tell us how the lesion started and if there are any triggers for it.
This could in fact be anything from insect / bug bites, dermatitis, heat rash, allergic reactions or eczema.

You could apply calamine lotion at the sites, keep the area well moisturized and wash the sites frequently. Avoidance of sun exposure would help too.

Let us know if you need any other information.

Regards