Difficult Psoriasis Cases Highlight Systemic Disease, Combination Therapy, and Precision Treatment at Science of Skin Summit

Modern psoriasis management increasingly requires dermatologists to look beyond visible plaques and consider the systemic disease, individual comorbidities, treatment history, and potentially even a patient's molecular profile.

During a case-based session at the Science of Skin Summit, Scott Drew, DO; April Armstrong, MD, MPH; and Erin Boh, MD, PhD, explored how complex psoriasis presentations can require clinicians to move beyond standardized treatment algorithms and individualize management.

Psoriasis Is More Than a Skin Disease

Dr. Drew opened with the case of a 15-year-old boy with extensive psoriasis whose disease had significantly affected his social life. After treatment with an IL-23 inhibitor, Dr. Drew reported that the teenager achieved Psoriasis Area and Severity Index (PASI) 92 within 3 weeks.

The dramatic skin response, however, was not Dr. Drew's principal teaching point. Laboratory testing revealed a glucose level of 386 mg/dL and triglycerides of 3500 mg/dL.

“Psoriasis is not just a disease of the skin and the joints,” Dr. Drew said. “It is a systemic inflammatory disease that we're responsible for taking care of.”

He encouraged dermatologists to consider what he called the “psoriasis march,” particularly because young patients may harbor important metabolic and other comorbidities even when their skin disease is the primary reason for presentation. 

An Unexpected Case of Cutaneous Tuberculosis

Dr. Drew's second case demonstrated a different challenge: recognizing an unexpected infection in a patient being managed for psoriasis and psoriatic arthritis.

The patient presented with an 8-week history of fever and a unilateral, nondermatomal pustular eruption with erythematous plaques on one arm. Because the patient was an avid gardener, Dr. Drew initially suspected sporotrichosis. Further evaluation, however, revealed mycobacteria, with biopsy demonstrating acid-fast bacilli.

The diagnosis was cutaneous tuberculosis (TB), and the patient was treated with RIPE therapy.

The case prompted discussion about TB screening in patients receiving biologic therapy. Dr. Drew noted that routine testing requirements differ according to biologic class, while other panelists emphasized that physicians should also consider local epidemiology and individual risk factors, including residence in or travel to areas with higher TB prevalence, congregate living environments, incarceration, and other potential exposures. 

Rapid Intervention for Erythrodermic Psoriasis

Dr. Armstrong presented a 78-year-old man with Parkinson disease and no previous history of psoriasis who developed severe erythrodermic psoriasis.

The patient had been receiving carbidopa/levodopa and subsequently had ropinirole added to his regimen. Because ropinirole was among the more recently introduced medications, it was discontinued amid suspicion of drug-induced disease, although Armstrong noted that her review found little literature linking the drug specifically to erythrodermic psoriasis.

The patient had already received several therapies with minimal improvement before arriving at Dr. Armstrong's clinic. Given the severity of his condition and the need for rapid disease control, Dr. Armstrong initiated bimekizumab and added cyclosporine.

Within approximately 4 weeks, edema and desquamation were improving. By approximately 7 to 8 weeks, Dr. Armstrong reported substantial improvement, allowing the patient to begin tapering cyclosporine.

The presentation also emphasized the importance of considering alternative causes when psoriasis or erythroderma develops unexpectedly in an older patient. Dr. Armstrong performed additional evaluation, including CBC and serum protein electrophoresis, which did not identify another cause in this patient.

Close involvement of the patient's family and assisted-living facility was also critical, she said, particularly for monitoring an elderly patient receiving combination therapy. 

Combination Therapy Rather Than an Immediate Switch

Dr. Armstrong's case led to a broader discussion of what clinicians should do when patients do not immediately achieve the desired response to biologic treatment.

Dr. Drew cautioned against declaring biologic failure prematurely. Instead of automatically switching therapies after an incomplete early response, he suggested that some patients may benefit from adding another treatment, potentially including a topical agent, cyclosporine, or narrowband UVB.

The larger principle was that clinicians should use the breadth of the psoriasis armamentarium rather than assuming every patient must respond adequately to a single medication. 

Could Molecular Testing Help Choose a Psoriasis Therapy?

Dr. Boh expanded that concept by discussing whether gene expression profiling could make treatment selection more precise.

She presented a 42-year-old man with longstanding psoriasis, obesity, irritable bowel syndrome, metabolic dysfunction-associated steatohepatitis, and joint disease who had received numerous previous therapies. Gene expression profiling indicated overexpression of IL-23 and IL-17, according to Dr. Boh.

Because the patient had previously worsened with IL-17 inhibition, Dr. Boh selected a different IL-23 inhibitor. His skin improved substantially, but his arthritis remained inadequately controlled, prompting her to add tofacitinib.

The case illustrated two principles central to Dr. Boh's presentation: previous clinical response remains important when selecting therapy, and combination treatment may be appropriate when a single agent addresses only part of a patient's disease.

Comorbidities also matter because inflammatory pathways involved in psoriasis can affect other organ systems. Dr. Boh emphasized that clinicians should avoid selecting a therapy that improves cutaneous disease at the expense of another existing condition. 

Toward Precision Medicine in Psoriasis

Dr. Boh described her experience with an RNA gene expression profiling test designed to characterize cytokine expression and help identify patients more likely to respond to therapies targeting TNF, IL-17, or IL-23 pathways.

The test uses a noninvasive skin sampling technique and, according to Dr. Boh, returns results in approximately 7 to 10 days. She reported using the findings alongside clinical characteristics, comorbidities, previous treatment response, and insurance considerations when selecting therapy.

Dr. Boh also described using molecular results when appealing insurance denials, particularly when an insurer requires a patient to try a therapy targeting a pathway that testing suggests may be less appropriate.

The speakers nevertheless stressed that even within a therapeutic class, patients may respond differently to individual drugs. A lack of response to one agent therefore does not necessarily establish that every therapy targeting that pathway will fail.

Ultimately, the panel advocated for a more individualized model of psoriasis care—one that incorporates systemic health, comorbidities, prior responses, therapeutic mechanisms, and, when appropriate, combination therapy.

“Our patient is our prime responsibility, the person in front of us,” Dr. Drew said. “Not every patient reads the textbook.”