Radiation Recall Dermatitis in Patients Treated With Immune Checkpoint Inhibitors: A Case Report and Literature Review.

Radiation recall dermatitis (RRD) is defined as a skin reaction in the previously irradiated area triggered by a systemic agent's administration. The use of immune checkpoint inhibitors (ICI) alone and in combination with other treatments is increasing in many cancers. ICI-associated radiation recall reactions such as dermatitis, pneumonia, and myelitis have been reported so far. We report a case of nivolumab (anti-programmed cell death protein-1 antibody) induced RRD in a patient with head and neck cancer and review the publications reporting RRD associated with other ICI in the literature. The patient was diagnosed with neck metastasis of unknown primary origin and underwent surgery followed by adjuvant chemoradiotherapy (CRT). During the follow-up, radiotherapy (RT) was performed to the left parotid region, right neck level 1b, and the left neck skin due to recurrence. After three months of the last RT session, she was started on nivolumab due to the metastatic disease. Four weeks later, she was represented with erythematous squamous plaque-like lesions starting from the left temporomandibular region and spreading to the anterior chest, which corresponded to the previously irradiated area. A biopsy was performed with the differential diagnosis of skin metastases which revealed subacute spongiotic dermatitis. The lesions completely regressed in two weeks with the use of topical steroids and antihistamine tablets. Nivolumab treatment was not interrupted, and no reaction was observed during or after the next cycle. Although RRD is rarely encountered clinically, it is a diagnosis that should be kept in mind while continuing treatment with systemic agents in patients with a history of RT. With the widespread use of ICI, RRD associated with these treatments could be better defined and appropriately managed.