Hypohidrosis as an immune-related adverse event of checkpoint inhibitor therapy

Immune checkpoint blockade therapies including cytotoxic-T-lymphocyte antigen 4 (CTLA-4) and programmed cell death protein-1 (PD-1) inhibitors have become indispensable tools for treating melanoma and other cancers. An increasing number of diverse cutaneous adverse reactions to immunotherapy have been documented in the literature and have been reported to affect up to 40% of patients treated with targeted therapies. Herein, we report a case of a patient with metastatic melanoma treated with checkpoint inhibitor therapy who developed vitiligo, gastritis and hepatitis, all identified as adverse immune events and attributable to his immunotherapy regimen. He subsequently developed acquired idiopathic generalized hypohidrosis with biopsy of lesional skin demonstrating a peri-eccrine lymphocytic infiltrate. These findings suggest this acquired generalized hypohidrosis represents a lymphocyte-mediated adverse immune event related to this patient’s checkpoint inhibitor therapy.