Context, not class, may be the key signal in systemic Janus kinase inhibitor exposure in mycosis fungoides/Sézary syndrome

This letter argues that the apparent risk signal associated with systemic Janus kinase inhibitors in mycosis fungoides/Sézary syndrome should be interpreted in light of clinical context, heterogeneous case sources, and diagnostic uncertainty. It highlights late-onset or erythrodermic dermatitis and the post-transplant setting as higher-risk contexts, while cautioning against assuming a uniform harmful class effect.