Radiation-induced bullous pemphigoid: a systematic review of an unusual radiation side effect.

Background: Percutaneous radiotherapy (RT) may cause a range of acute and late side effects of the skin within the irradiated area. In rare cases radiotherapy can cause bullous pemphigoid (BP). BP is reported to occur mainly within irradiated fields following radiation treatment. Exceptionally, BP may arise during RT. It is unclear which mechanism exactly triggers BP following megavoltage irradiation and whether there is a potential association with hormonal anticancer treatment.

Methods: A systematic literature based review was performed. Publications reporting histologically confirmed BP and a treatment with RT were retrieved based on a standardized query using electronic databases. A standardized quality assessment was applied.

Results: Out of 306 potentially relevant publications 21 were identified to be relevant and included in this review. An association between RT and BP was reported in 27 patients. The majority developed BP after RT and a median dose of 50 Gy. Four patients developed BP during RT after a minimal dose of 20 Gy.

Conclusions: BP induced by RT was observed predominantly in patients with breast cancer. In all reported cases, there is a clear relationship with RT. Therefore, BP may be considered as RT-induced side effect. RT can induce a BP following a minimal dose of 20 Gy. New biological agents may play a role in the future treatment of BP.