Pembrolizumab-associated expansion of radiation-induced morphoea responsive to dupilumab: a case report.

Abstract

Radiation-induced morphea (RIM) is a rare but distinctive inflammatory complication of therapeutic radiation.1 It most commonly presents as painful sclerosis of the epidermis and dermis limited to the irradiated field. Morphea has also been reported as an immune-related adverse event (irAE) induced by anti-programmed death-1 (PD-1) immune checkpoint inhibitors (ICIs).2,3 We report a patient who first received local radiation therapy to the thorax for lung adenocarcinoma that was complicated by RIM. The patient's morphea then progressed widely beyond the irradiated field in the setting of pembrolizumab therapy. Histopathology and imaging confirmed morphea extending beyond the irradiated field and with deeper muscular and fascial involvement. Pain and edema progressed through multiple lines of toxicity-directed therapy, but ultimately responded significantly to dupilumab. Response was confirmed clinically and radiographically, and the patient was able to resume ICI therapy. This case report highlights the ability of ICIs to induce progression of pre-existing RIM and supports the consideration of dupilumab in refractory cases.