The coexistence of Alopecia Universalis (AU) and severe plaque psoriasis is rare, presenting a unique challenge in selecting systemic therapy. We report the case of a 32-year-old male with a lifelong history of AU (SALT 100%) who developed sudden-onset, aggressive psoriasis (PASI 25.4, DLQI 18) involving the limbs and trunk. While his baseline labs and imaging were unremarkable, his clinical response to treatment was highly divergent. We initiated adalimumab (40 mg every other week), which successfully cleared his psoriatic plaques but failed to trigger any hair regrowth.

This "split" response underscores the distinct cytokine environments of these two conditions: psoriasis is driven primarily by the Th17/TNF- axis, whereas AU relies on the JAK-STAT pathway. This case suggests that for patients with this specific comorbidity, traditional TNF- inhibitors may be insufficient. Instead, clinicians should consider dual-targeting therapies, such as JAK inhibitors, to address both inflammatory pathways simultaneously.