# The Completion of Postoperative Radiotherapy After Breast-Conserving Surgery in a Patient With Recurrent Erythema Multiforme: A Case Report

## TL;DR

This case report discusses safely administering radiotherapy to a patient with a history of erythema multiforme after breast cancer surgery.

## Contribution

The paper presents a novel clinical case demonstrating safe radiotherapy delivery in a patient with recurrent erythema multiforme.

## Key findings

- Radiotherapy was successfully administered during a less active phase of the patient's erythema multiforme.
- One year after treatment, there was no recurrence of erythema multiforme or significant side effects.
- The case suggests radiotherapy can be safely used in patients with recurrent erythema multiforme with proper timing.

## Abstract

Radiotherapy (RT) can induce dermatitis and exacerbate a patient's preexisting skin conditions. We present a case of RT in a 61-year-old Japanese woman with a history of erythema multiforme (EM). She was diagnosed with a nodule on her right breast during therapy for EM. EM was noticed on the anterior chest and upper and lower extremities. RT was initially postponed due to exacerbation of EM before postoperative RT for right breast cancer. However, considering that EM tends to recur every one to two months, RT was commenced during a period of less active dermatitis, and a total dose of 50 Gy of conventional irradiation was successfully administered. One year after RT, there was no EM recurrence, dermatitis development, obvious late effects, or radiation pneumonitis. Our experience suggests that RT can be administered relatively safely to patients with recurrent EM but should be administered with caution.