Challenges in Psoriatic Arthritis

PHILADELPHIA—Despite a large and ever-growing number of therapeutic options for our patients with psoriatic disease, it is not uncommon for us come across scenarios in which a patient’s response to therapy does not match our expectations and our shared goals for treatment.

Dr. Merola

We all have those patients—the ones whose joints improve with one drug, but they continue to have active psoriasis, and vice versa. We also all have those few patients who seem refractory to multiple—and sometimes seemingly every—therapy prescribed. At ACR Convergence 2022, Joseph Merola, MD, MMSc, an associate professor of medicine and dermatology at Harvard Medical School, Brigham and Women’s Hospital, Boston, discussed treatment strategies for these exact patients. As a triple board-certified internist, rheumatologist and dermatologist, Dr. Merola is uniquely positioned to share insights on this topic. He serves as the vice chair for clinical trials and innovation and is director of the Center for Skin and Related Musculoskeletal Disease, a combined clinic seeing patients with psoriatic diseases.

Is the Diagnosis Correct?

When patients don’t respond the way we’d like, sometimes we’ve got to go back and ask: Is the diagnosis correct in the first place?

Even with plaque psoriasis, a differential diagnosis needs to be considered. Dr. Merola shared the case of a young woman referred to his combined clinic with well-demarcated, erythematous, psoriatic lesions of the buttocks that weren’t responding to psoriasis treatments. Her rheumatologist assumed that her musculoskeletal symptoms were related to the skin lesions and was treating her with methotrexate and subsequent TNF inhibitor therapy for psoriatic arthritis and psoriasis, with no improvement in symptoms.

A skin biopsy revealed cutaneous T cell lymphoma.

“If there’s a disconnect, remember to rethink your diagnosis. If things aren’t behaving as you’d expect, think about a dermatology referral and skin biopsy as appropriate,” Dr. Merola advised.

In this patient’s case, fibromyalgia and cutaneous T cell lymphoma were the most likely diagnoses. The morphologic differential diagnosis for plaque psoriasis was reviewed, including such entities as nummular dermatitis, psoriasiform variants of subacute cutaneous lupus erythematosus, psoriasiform lesions reported in anti-TIFi-γ dermatomyositis, allergic or irritant contact dermatitis, lichen simplex chronicus and seborrheic dermatitis.

When it comes to inflammatory arthritis symptoms in psoriasis patients, “remember that psoriasis and other joint diseases aren’t mutually exclusive,” Dr. Merola noted. He shared examples of patients who had concomitant psoriasis and what was clinically more consistent with seropositive rheumatoid arthritis, Lyme disease and crystal disease presentations—PsA patients are at a nearly fivefold increased risk for gout.¹