Moderate-to-Severe Psoriasis With Latent Tuberculosis and Metabolic Comorbidity
A 56-year-old man with an 18-year history of plaque psoriasis presents for treatment review. His body surface area involvement is 22% and PASI is 18; topical corticosteroids and narrowband UVB have failed. He has type 2 diabetes (HbA1c 8.1%), hypertension, a body mass index of 33, and drinks three to four beers daily. He smokes one pack per day. He has no joint pain or swelling. An interferon-gamma release assay is positive; chest radiograph is normal and he has never received tuberculosis treatment. Medications are metformin, lisinopril, and atorvastatin. AST is 48 U/L and ALT is 52 U/L (upper limit 40). He asks about a biologic advertised on television and wants 'the safest one for my liver.'
1. Select and sequence a systemic regimen. Which agents would you avoid, and what must be completed before the first biologic dose?
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Severity (BSA 22%, PASI 18) justifies systemic therapy. The positive interferon-gamma release assay with a normal chest radiograph indicates latent tuberculosis infection; treatment must be arranged before or concurrently with biologic initiation. Tumor necrosis factor inhibitors carry the highest reactivation risk and should generally be deferred until latent tuberculosis prophylaxis has been underway for at least one month. Interleukin-17 and interleukin-23 inhibitors have much lower tuberculosis risk, but latent infection still requires treatment.
I would avoid methotrexate because of daily alcohol use, transaminitis, and metabolic syndrome; avoid acitretin because alcohol can promote etretinate formation and because of dyslipidemia; and avoid cyclosporine because of hypertension, diabetes, and nephrotoxicity. Apremilast is safer but less effective for this severity. A reasonable choice is an interleukin-23 inhibitor, or an interleukin-17 inhibitor if rapid clearance is prioritized. Before starting, obtain CBC, chemistry, hepatitis B and C, and HIV testing; update non-live vaccines; document tuberculosis treatment; and counsel about alcohol reduction, smoking cessation, and glycemic control.
2. Six weeks after the second biologic dose he presents with fever, productive cough, and oxygen saturation 91%. What are the immediate steps and when would you restart?
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This is a possible serious bacterial pneumonia or opportunistic infection on a biologic. Hold the biologic immediately. Obtain blood cultures, sputum or respiratory viral testing, chest imaging, CBC, chemistry, and lactate; start empiric antibiotics according to local guidance and severity. Give oxygen and fluids as needed, and involve infectious disease and critical care if hypoxemic. Do not restart the biologic until the infection has resolved clinically and radiographically and the patient is off antibiotics, typically after a shared decision with infectious disease. Reassess whether the infection was related to the biologic, whether there is an underlying immunodeficiency, and whether a different mechanism is preferable. Counsel the patient that fever, dyspnea, or productive cough requires urgent evaluation while on biologic therapy.
3. He later develops dactylitis and inflammatory axial morning stiffness. How does that alter your biologic choice?
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New peripheral arthritis and axial symptoms change the target from skin alone to skin plus psoriatic arthritis. Interleukin-17 inhibitors and tumor necrosis factor inhibitors have the strongest evidence for axial involvement; interleukin-23 inhibitors are effective for peripheral psoriatic arthritis but are generally not the first choice for prominent axial disease. Tumor necrosis factor inhibitors remain attractive for joint disease but carry the highest tuberculosis reactivation risk, so latent tuberculosis treatment must be completed or well underway before starting one.
A practical choice is an interleukin-17 inhibitor, provided there is no history of inflammatory bowel disease, which would favor a different mechanism. If axial disease dominates or interleukin-17 therapy fails, reconsider a tumor necrosis factor inhibitor after tuberculosis prophylaxis. Coordinate with rheumatology, document baseline spinal symptoms and imaging, and use a treat-to-target approach that assesses both skin and musculoskeletal response rather than skin alone.