# Radiation Recall Phenomenon Following Vaccination in a Patient With Prior Radiation to Lower Extremity Liposarcoma

## TL;DR

A patient with a history of radiation for liposarcoma developed a blister at the same site after receiving multiple vaccines, suggesting vaccination can trigger radiation recall phenomenon.

## Contribution

This case report identifies vaccination as a novel trigger for radiation recall phenomenon in previously irradiated tissue.

## Key findings

- A 67-year-old woman developed a blister at a prior radiation site after receiving vaccines.
- The blister progressed to an ulcer over two months without affecting the active radiation site.
- Vaccination is highlighted as a potential trigger for radiation recall phenomenon.

## Abstract

Radiation recall phenomenon (RRP) is a rare inflammatory reaction in previously irradiated tissue triggered by agents such as chemotherapy or vaccines. A 67-year-old female patient who had undergone radiation to the right thigh for liposarcoma developed a blister at the same site during whole breast radiation for invasive lobular carcinoma. This occurred three days after receiving COVID-19, respiratory syncytial virus (RSV), and influenza vaccines. The reaction progressed to an ulcer over two months, while her active breast radiation site remained unaffected. This case highlights vaccination as a potential RRP trigger and the selective involvement of prior radiation fields. Awareness of RRP in vaccinated patients with a history of radiation is essential, warranting further research into its mechanisms.