Psoriasis Nature Reviews Disease Primers Many treatment guidelines for psoriasis rely heavily on body surface area (BSA) involvement to determine disease severity and eligibility for systemic therapies like biologics. Traditionally, patients with less than 10% BSA involvementespecially Psoriasis Pathogenesis and Treatment Healing the Gut to Treat Psoriasis? Next Steps in Dermatology Many treatment guidelines for psoriasis rely heavily on body surface area (BSA) involvement to determine disease severity and eligibility for systemic therapies like biologics. Traditionally, patients with less than 10% BSA involvementespecially Gray Market Peptides: So Much Hype, So Little Data