hive on top of scar (from removal of birthmark) on face

i'm a 32 year old female with no major health issues.  i do have some minor (low thyroid, low iron) issues for which i take meds.

i was born with a birthmark on my cheek that was about the size of a dime/nickel.  i had three surgeries to have it removed when i was 5, 7, 8 years old because the doctor felt that due to its location and type of mole, it could become skin cancerous.  the scar has never bothered me until now.

over the last several months, for no apparent reason, i get a hive right beside/over top of my scar.  it causes the entire scar area to turn red and sometimes the entire scar gets raised.  the reaction lasts about an hour.  it gets slightly itchy, but not itchy like a typical hive.  it's more like a nerve-ending reaction...pins and needles as it's raising.

i've tried to take note of products/creams/meds/sun/etc that could have caused the reaction, but it's so random...there's nothing linking any of the reactions.  it's happened about 10 times over the past several months.

what's going on?  this sounds silly, but do you think there could still be birthmark left that's not outwardly visible?  could i have sarcoidosis in the scar?  it's just very bizarre to me.  i would think that if i was allergic to something, i would have hives in a different spot each time...not the same spot on top of my scar!

i have a picture that i could send if you'd like.

thanks.
maria

[Jasmina Jankicevic, MD, MSc, CCRP]

Dear Maria,

In many skin diseases (e.g., Psoriasis vulgaris, Lichen planus, Lupus erythematodes, Sarcoidosis,  Vitiligo, etc.) skin changes are more prone to develop on previously traumatized (including scars) skin. This is known as Koebner phenomenon. To establish diagnosis, if area is untreated, it is quite beneficial to compare results of clinical evaluation and histopathological analysis.

In general, evanescent, hives-like skin reaction could be contact urticaria. Localized swelling and redness occurs after direct contact with offending substance(s) such as ingredients of cosmetics, topical medicaments, etc. It resolves completely once the offending substance is no longer in contact with the skin. Diagnosis of contact urticaria can be confirmed by skin ***** tests and scratch patch tests.


Yours in Optimal Health,
Dr. Jasmina Jankicevic

[mtkst13]

One more thing...when i get the "reaction", the scar is the only place i get the reaction.  i don't get hives/itchies/swelling/redness any other place on my body.