Eruptive keratoacanthoma secondary to immune checkpoint inhibitors: a narrative review.

The use of immunotherapy is an emerging treatment option for advanced malignancies. Cutaneous adverse events following cancer immunotherapy are well-documented in the literature. The rarer cutaneous adverse effects are less characterized, including eruptive keratoacanthomas (KA). Despite surgical excision remaining the treatment of choice for KA, several case reports have shown intralesional injections to be an effective, non-invasive treatment modality for this cutaneous adverse event. We reviewed the PubMed database for patients presenting with eruptive KA secondary to immune checkpoint inhibitor use. We also included three previously unpublished cases from our own institution. We identified a total of 19 patients (47.4% male, mean age 78.9 years, range 67-92 years). Patients were treated with intralesional injections, systemic agents, or alternative therapy (n = 7, 5, 7 respectively). Improvement of eruptive KA was observed in 89.5% of patients. Immunotherapy was continued or restarted in 13 of 19 cases. Intralesional injection of triamcinolone or methotrexate resulted in complete resolution in all patients when response was characterized. We believe intralesional injections may be an effective, less invasive treatment option than surgical excision when treating eruptive keratoacanthomas secondary to immunotherapy.