Recurrent contact dermatitis, or cellulitis post RT?

Certainly an uncomfortable situation for you, and nerve wracking too. So sorry this is happening.

To me the tingling,itching onset sounds like special cells known to cause these symptoms (mast cells, round cells with prickly-looking particles on their surface) are stimulated in the area and releasing their inflammatory proteins. Are you an allergy prone person in general? You can see similar response in some individuals just by scratching your arm in that a red streak will develop and perhaps itching. Since these are histamine productions amongst other, a good antihistamine may well help curb your symptoms when these events occur. Cellulitis can cause some similarity in symptoms, with streaking and swelling, but it's rather unusual to have it specific to one spot like you are describing imo.  Your problem sounds like a localized production of inflammatory proteins.

You need a good breast surgeon to help you out. The area you had the laser on to remove the telangectasias should be examined and biopsied as you say it just has been. This will help rule out any underlying more serious problem and your breast surgeon should check you out again in a timely manner regardless of the biopsy result. Just to see no further skin change like deepening of the redness to a more blue hue and swelling with small vessels.

After the breast surgeon gives the clear but I'll see you back, an allergist might be helpful to see also. They usually recommend cutting back on various detergents, lotions, maybe foods and then adding back to see if you have the problem again. Particularly important is the ruling out too of a contact dermatitis which might be causing a bit of radiation recall in the site. That's a tough diagnosis, and may need the input from your past radiation oncologist for their help too.

I hope you find some answers to this vexing problem. Let us know how you do please.

My best to you,

Tender