TNF and achondroplasia: Apremilast, an oral phosphodiesterase 4 inhibitor, modulates pro-inflammatory pathways to promote anti-inflammatory activity, increases intracellular concentrations of cAMP, and blocks the production of pro-inflammatory cytokines, such as TNF-α, IFN-γ, IL-17, IL-23, and IL-12 (58, 59), which have been shown to be involved in the inflammatory response in systemic pustulosis and ACH (60).