Are there any known issues related to radiation in the setting of vitiligo?

I have treated several breast cancer patients with vitiligo with both photon and proton radiation therapy. In Caucasian people with the disease, I have found that the areas of vitiligo either stay hypopigmented (no pigment change) or I have had a handful of patients turn bright red in the areas of hypopigmentation early on during their treatment (1-2 weeks). I have not found increased desquamation in the areas of hypopigmentation. Long-term, I have found these areas return to being hypopigmented. I personally can't remember treating an African American patient with vitiligo in the field but would imagine things would be similar.

Regarding the report above, the reporting institution noted only 1 case of in-field depigmentation. We have to r...

I have experienced marked permanent in-field hypopigmentation in several patients, including Caucasian and African-American skin. For one patient it predated any vitiligo elsewhere for 2-3 years.

I consequently warn all patients with vitiligo of this possibility.

They did not experience undue acute skin toxicity.

I have also treated several patients with vitiligo that have had no late effects.

I had an interesting patient with vitiligo in her breast. She developed classic erythema in the depigmented skin and hyperpigmentation without significant erythema in her normally pigmented skin (which was brown to begin with). She did fine in follow up but still had some lingering hyperpigmentation in her "normal" skin that was not depigmented.

Yes, there is potential for Koebner phenomenon and they should be counseled as such. https://www.ncbi.nlm.nih.gov/pubmed/8018572/

I treated an Indian female who developed vitiligo shortly after her breast cancer diagnosis but limited to her neck. The vitiligo progressed in a few areas but following radiation the depigmentation in the treated breast, including areola, was much more pronounced than her contralateral breast. This has been a source of stress for her and I will certainly counsel patients about this risk in the future.

I have also seen increased hypopigmentation in-field in a Caucasian woman treated with RT for H&N cancer. She didn't mind it too much since her skin was already light and the hypopigmented area enlarging was not apparent, but if you looked carefully you can tell it has spread. She did not have more than expected acute skin toxicity though.