Pembrolizumab resolves adult ashy dermatosis developing in patients with squamous cell carcinoma of the lung.

Ashy dermatosis is a rare cutaneous disorder of unknown etiology. We describe a case of adult ashy dermatosis developing in a patient with squamous cell carcinoma of the lung, which was resolved by the administration of pembrolizumab in parallel with multiple vitiligo. Interestingly, immunohistochemical staining revealed that lesional skin of the ashy dermatosis contained cytotoxic T cells and programmed death ligand 1 expressing cells. To our knowledge, this is the first case of adult ashy dermatosis resolved by pembrolizumab.