Dr. Megan Prouty guides us through important points from her lecture, Complex Psoriasis Cases: Navigating Diagnostic & Therapeutic Challenges, at the 2nd Annual Elevate-Derm Alliance Summer Conference at the Grand Hyatt Deer Valley in Park City, Utah.

In this video

In conversation with dermatology NP Veronica Richardson, Dr. Prouty describes how her thinking has shifted since residency, when she considered dermatitis and psoriasis "two different things, different people." The longer she's practiced, the more she sees patients with both eczematous and psoriasiform lesions on the same body — a classic plaque on a knee or elbow, and an ill-defined, eczematous plaque somewhere like the neck that "doesn't look like the other areas of involvement." Many arrive as outside referrals who have failed efficacious biologics, because they truly have psoriasis but also an untreated eczematous component: they start a psoriasis treatment, some areas clear, then flare elsewhere with ill-defined disease.

Her approach is largely trial and error guided by morphology. She'll commit to the disease she thinks is most likely and treat accordingly; when unsure, she reaches for medications that work for both. She rarely biopsies, noting results often come back as "psoriasiform dermatitis" — unhelpful, and sometimes a red herring, especially on the scalp. For TNF-flared cutaneous disease she first switches to an IL-23 or IL-17 inhibitor; if that fails, she turns to agents effective for both conditions such as methotrexate, upadacitinib, and PDE4 inhibitors (oral apremilast, oral and topical roflumilast). Combination therapy is off-label, she reminds us, but supported in the literature and, in her experience, "totally works, and it's very satisfying."

  • Suspect a psoriasis-dermatitis overlap when a patient has two morphologies — classic plaques plus ill-defined eczematous lesions — or when they flare in new areas after partial improvement on a psoriasis biologic.
  • Failed efficacious biologics often signal an untreated eczematous component, not treatment-resistant psoriasis.
  • Biopsies are frequently unclear (commonly reading as "psoriasiform dermatitis") and can be a red herring; Dr. Prouty rarely biopsies and treats based on morphology.
  • For TNF-flared cutaneous disease with prior plaque psoriasis, switch first to an IL-23 or IL-17 inhibitor and reassess.
  • When one treatment must cover both diseases, consider methotrexate, upadacitinib, or PDE4 inhibitors (oral apremilast, oral/topical roflumilast); combination therapy is off-label but documented.