Anti-CTLA-4 therapy-associated granuloma annulare in chronic myelomonocytic leukemia.

Immune checkpoint inhibitor (ICI) therapies activate the immune system to unmask cancer cells that the body might otherwise not detect. These cancer therapies alter the immune system at different "checkpoint" proteins such as PD-1, PD-L1, or CTLA-4 to better target tumor cells, but also have the potential to affect normal tissues. In patients receiving ICI therapy, cutaneous reactions have been frequently documented, ranging from mild urticarial rashes to widespread cutaneous necrosis. Proper identification and management of ICI therapy side effects is essential to the care of these patients. Here, we present an unusual granulomatous cutaneous reaction in a patient receiving anti-CTLA-4 therapy for chronic myelomonocytic leukemia.