What is the proposed culprit?
Fang X et al describe 4 patients with skin hyperpigmentation secondary to nitrous oxide abuse. Nitrous oxide abuse is a well known neurotoxin whereas skin hyperpigmentation occurs much less frequently. (Fang X et al. Skin hyperpigmentation: A rare presenting symptom of nitrous oxide abuse. Clin Tox 2019. EPUB ahead of print. doi: 10.1080/15563650.2019.1665181)
What is the proposed culprit to these findings?