Lesson
Build the Immune Keratinocyte Axis
Psoriasis is not simply rapid skin growth. Genetic susceptibility, innate immune activation, IL-23 dependent T cell signaling, IL-17 and TNF, and keratinocyte feedback create a self-reinforcing inflammatory circuit.
- Dendritic cell
- IL-23
- Th17
- IL-17
- TNF
- Keratinocyte
Dendritic and tissue signals establish an IL-23 rich inflammatory environment.
IL-17 and TNF activate keratinocytes and recruit additional immune cells.
Accelerated turnover, incomplete maturation, vessels, and inflammation create scale and erythema.
Start with immune activation
Dendritic cells and other innate signals promote IL-23 dependent survival and activation of type 17 immune responses. Genetic susceptibility, infection, trauma, smoking, obesity, and medicine exposure can influence expression without explaining every case.
Follow the cytokine circuit
IL-17A, IL-17F, TNF, and related mediators activate keratinocytes. Keratinocytes then release chemokines, antimicrobial peptides, and inflammatory signals that recruit more immune cells and sustain the lesion.
Explain the plaque
Accelerated epidermal turnover, incomplete maturation, vascular dilation, and inflammatory cell accumulation produce sharply demarcated erythematous plaques with scale. Pinpoint bleeding after scale removal is a classic finding, not a test that must be provoked.
Use the Koebner phenomenon
New lesions can appear at sites of trauma. Scratching, friction, burns, tattoos, or procedures can reproduce disease in susceptible skin, which makes skin protection part of management.
Map treatment to biology
Corticosteroids reduce broad inflammation, vitamin D analogs influence keratinocyte differentiation, PDE4 and TYK2 inhibitors reduce intracellular signaling, and biologics selectively block TNF, IL-12/23, IL-17, or IL-23 pathways.
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Lesson
Recognize Phenotype, Site, and Urgency
The word psoriasis does not define one presentation. Morphology, distribution, symptoms, systemic illness, and recent medicine changes separate routine plaque care from urgent erythrodermic or pustular disease.
- Plaque
- Inverse
- Guttate
- Nail
- Erythrodermic
- Generalized pustular psoriasis
Scalp, folds, nails, palms, soles, face, and genitals can change treatment and burden.
An abrupt small lesion eruption can follow infection without proving active infection remains.
Generalized pustules, erythroderma, fever, pain, or organ dysfunction require urgent care.
Recognize plaque disease
Stable plaque psoriasis usually produces well demarcated erythematous plaques with scale on extensor surfaces, scalp, trunk, or other sites. Pruritus, pain, fissuring, and sleep disruption can be substantial even when extent is limited.
Identify special sites
Inverse disease affects folds with less visible scale. Genital, facial, scalp, palmoplantar, and nail disease can create disproportionate functional and psychosocial burden. Nail pitting, onycholysis, and subungual hyperkeratosis also increase suspicion for psoriatic arthritis.
Recognize guttate disease
An abrupt eruption of many small lesions often follows streptococcal infection, especially in younger patients. Confirm the pattern and assess the trigger rather than prescribing antibiotics for psoriasis without evidence of active infection.
Escalate erythroderma
Near generalized erythema and scale can impair temperature control and fluid balance and can accompany infection, high output cardiac stress, or medication withdrawal. Hospital level evaluation may be required.
Escalate pustular disease
Generalized sterile pustules with erythema, pain, fever, malaise, leukocytosis, or organ dysfunction suggest generalized pustular psoriasis. This is distinct from plaque psoriasis and can be life threatening.
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Lesson
Measure Disease Beyond Surface Area
Body surface area is useful but incomplete. Severity also lives in lesion intensity, symptoms, special sites, function, quality of life, joint disease, comorbidity, and failure of appropriate treatment.
- BSA
- PGA
- PASI
- DLQI
- Special sites
- Psoriatic arthritis
Extent and global assessment establish a reproducible objective baseline.
Pain, itch, sleep, function, intimacy, work, and treatment effort reveal hidden severity.
Psoriatic arthritis, cardiometabolic risk, bowel disease, mood, and uveitis change care.
Quantify extent and intensity
One patient palm, including fingers, approximates one percent body surface area. Physician Global Assessment describes overall morphology. PASI is common in trials, while BSA and global assessment are often more practical in routine care.
Measure patient burden
Pruritus, pain, sleep, clothing, intimacy, work, sport, treatment effort, and confidence reveal burden that extent misses. DLQI, Psoriasis Symptom Inventory, and similar tools can make that burden visible.
Protect special sites
Disease of the face, genitals, hands, feet, scalp, or nails may justify advanced therapy despite limited BSA because it can impair identity, mobility, work, sleep, or relationships.
Screen for psoriatic arthritis
Ask about prolonged morning stiffness, swollen joints, dactylitis, heel or tendon pain, inflammatory back symptoms, and functional decline. Suspected inflammatory joint disease warrants rheumatology evaluation before irreversible damage accumulates.
Screen systemic comorbidity
Review cardiovascular risk, obesity, diabetes, hypertension, dyslipidemia, smoking, alcohol, depression, suicidality, inflammatory bowel disease, uveitis, liver disease, and treatment specific infection risk.
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Lesson
Engineer a Topical Regimen That Can Work
Topical success depends on active ingredient, potency, vehicle, site, duration, quantity, technique, and a plan the patient can sustain. A prescription without those choices is incomplete.
- Corticosteroid potency
- Vitamin D analog
- Tazarotene
- Calcineurin inhibitor
- Keratolytic
- Vehicle
Ointment, cream, solution, and foam solve different site and adherence problems.
Corticosteroid potency and duration must fit plaque thickness and skin vulnerability.
Vitamin D analogs, tazarotene, calcineurin inhibitors, and selected adjuncts support control.
Match vehicle to site
Ointments are occlusive and useful for thick dry plaques, creams are versatile, solutions and foams can improve scalp delivery, and patient preference can determine whether any product is actually used.
Use corticosteroid potency deliberately
Potent agents can control thick plaques, while face, folds, and genital skin require lower exposure and steroid sparing strategies. Prolonged or excessive use can cause atrophy, striae, telangiectasia, tachyphylaxis concerns, and systemic absorption.
Combine complementary mechanisms
Vitamin D analogs such as calcipotriene influence proliferation and differentiation and are often paired with corticosteroids. Combination products can improve efficacy and simplify use while retaining dose and site limits.
Use steroid sparing options
Tazarotene can reduce plaque thickness but irritates and is avoided in pregnancy. Topical calcineurin inhibitors are used off label on sensitive areas because they avoid steroid atrophy, but can burn and carry labeling precautions.
Use older adjuncts selectively
Salicylic acid can remove scale but increases absorption of other topicals and can cause toxicity over large areas. Coal tar and anthralin can help selected patients but odor, staining, irritation, and complex technique limit use.
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Lesson
Use Modern Nonsteroidal Topicals Precisely
Tapinarof and roflumilast expand nonsteroidal treatment, especially when long term steroid burden, special sites, or vehicle preference matters. Their formulations and age boundaries are not interchangeable.
- Tapinarof
- Aryl hydrocarbon receptor
- Roflumilast
- PDE4
- Cream
- Foam
A thin layer once daily treats adult plaque psoriasis without topical corticosteroid exposure.
Roflumilast cream 0.3 percent supports once daily plaque treatment including folds.
From age 12, foam improves hair bearing delivery with essential flammability counseling.
Use tapinarof for adult plaque psoriasis
Tapinarof cream 1 percent is an aryl hydrocarbon receptor agonist applied as a thin layer once daily to affected areas in adults. Wash hands afterward unless the hands are treated.
Counsel tapinarof adverse effects
Folliculitis, nasopharyngitis, contact dermatitis, headache, pruritus, and influenza were among reactions reported more often than vehicle in plaque psoriasis trials. Reassess irritation rather than layering more product.
Use roflumilast cream
Roflumilast cream 0.3 percent is a topical PDE4 inhibitor for plaque psoriasis in patients two years and older under current labeling. Apply once daily, including intertriginous areas when affected.
Use roflumilast foam
Roflumilast foam 0.3 percent treats scalp and body plaque psoriasis in patients 12 years and older. Shake, apply once daily to dry affected skin or scalp, rub in, wash hands, and avoid flame or smoking during and immediately after use.
Respect systemic boundaries
Both roflumilast formulations are contraindicated in moderate to severe hepatic impairment. Diarrhea, headache, insomnia, nausea, and local reactions can occur, and interaction review matters because topical exposure is not zero.
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Lesson
Use Light as a Measured Treatment
Phototherapy is controlled treatment, not a recommendation to tan. Wavelength, dose, schedule, photosensitizing medicines, skin type, cumulative exposure, and access determine whether it is appropriate.
- Narrowband UVB
- Targeted UVB
- Excimer
- PUVA
- Photosensitizer
- Cumulative exposure
Measured UVB can treat plaque or guttate disease without psoralen photosensitization.
Excimer and targeted systems reduce exposure of uninvolved skin.
Psoralen adds medication, eye, nausea, and cumulative carcinogenic constraints.
Prefer narrowband UVB for many patients
Narrowband UVB is a common office based option for widespread plaque or guttate psoriasis. It reduces inflammatory signaling and can be used without an oral photosensitizer.
Target limited disease
Excimer laser and other targeted UVB systems concentrate treatment on localized plaques and reduce exposure of uninvolved skin. They still require controlled dosing and eye protection.
Understand PUVA
Psoralen plus UVA can be effective but adds systemic or topical photosensitization, eye protection requirements, drug interactions, nausea with oral psoralen, and greater cumulative carcinogenic concern.
Prevent treatment injury
Review photosensitizing medicines, prior skin cancer, burns, pigment response, and exposure history. Erythema timing guides dose adjustment, and blistering is toxicity rather than proof of efficacy.
Design for feasibility
Travel, work, copay, equipment access, home unit quality, and frequency often determine adherence. A theoretically effective plan that a patient cannot attend is not an effective plan.
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Lesson
Select Oral Systemic Therapy by Patient Constraint
Oral systemic drugs differ more than their route suggests. Speed, organ toxicity, reproductive risk, infection, interaction burden, renal function, and monitoring determine which option is usable.
- Methotrexate
- Cyclosporine
- Acitretin
- Apremilast
- Deucravacitinib
- TYK2
Methotrexate, cyclosporine, and acitretin require distinct organ and reproductive safeguards.
Titration, weight, mood, interactions, and renal function shape tolerability.
Deucravacitinib provides once daily adult therapy with infection and vaccine boundaries.
Use methotrexate with weekly discipline
Methotrexate can treat skin and joint disease but requires strict weekly dosing, blood count, renal and hepatic assessment, interaction review, reproductive planning, and counseling about infection and pulmonary or hepatic toxicity.
Use cyclosporine for rapid control
Cyclosporine can act quickly in severe, recalcitrant, pustular, or erythrodermic disease but nephrotoxicity, hypertension, interactions, malignancy risk, and duration limits make it a monitored bridge rather than a casual long term choice.
Use acitretin within absolute reproductive safeguards
Acitretin treats severe psoriasis and can help pustular disease without broad immunosuppression. It is highly teratogenic, requires pregnancy avoidance for at least three years after discontinuation, and requires lipid, hepatic, mucocutaneous, skeletal, and alcohol counseling.
Use apremilast with titration and renal adjustment
Apremilast inhibits PDE4 and is titrated to reduce gastrointestinal effects. Monitor weight and mood. Strong CYP inducers can reduce exposure. Severe renal impairment requires once daily maintenance under current labeling.
Use deucravacitinib as a selective TYK2 inhibitor
Deucravacitinib 6 mg once daily treats adult moderate to severe plaque psoriasis and, under the June 2026 label, active adult psoriatic arthritis. Screen infection and TB risk, avoid live vaccines, review liver disease and laboratory concerns, and do not combine with other potent immunosuppressants.
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Lesson
Choose a Biologic Pathway, Not Just a Brand
Biologic selection begins with the target and the patient. Skin efficacy, joint disease, inflammatory bowel disease, infection, liver disease, weight, injection schedule, pregnancy planning, and access can point in different directions.
- TNF
- IL-12/23
- IL-17A
- IL-17 receptor
- IL-17A and F
- IL-23 p19
Joint evidence, infection, heart failure, demyelination, pregnancy, and access guide selection.
Skin and joint efficacy must be balanced against bowel disease, candidiasis, and product specific warnings.
Long intervals and strong skin efficacy can be useful when the comorbidity profile fits.
Map the major families
TNF inhibitors include adalimumab, certolizumab, etanercept, and infliximab. Ustekinumab blocks IL-12/23 p40. IL-17 pathway agents include secukinumab, ixekizumab, brodalumab, and bimekizumab. Guselkumab, risankizumab, and tildrakizumab block IL-23 p19.
Use comorbidity as a selector
Psoriatic arthritis may favor agents with joint indications. Active inflammatory bowel disease can steer away from IL-17 pathway therapy. Heart failure, demyelinating disease, recurrent infection, hepatitis, and pregnancy planning can alter the balance for TNF and other pathways.
Screen before immune modulation
Evaluate active and latent infection, TB, hepatitis risk when relevant, vaccines, malignancy history, inflammatory bowel disease, mood history, and baseline laboratory needs according to the exact product. Avoid live vaccines during many biologic regimens.
Know the important exceptions
Brodalumab blocks the IL-17 receptor and retains a boxed warning and restricted REMS for suicidal ideation and behavior, with Crohn disease contraindication. Bimekizumab blocks IL-17A and IL-17F and requires TB evaluation, liver testing, vaccination review, and attention to infections including candidiasis and to inflammatory bowel disease.
Treat biosimilars as regulated biologics
An FDA approved biosimilar has no clinically meaningful differences in safety, purity, and potency from its reference product within approved conditions. Product identity, interchangeability status, device, payer rules, and continuity still require careful implementation.
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Lesson
Stabilize Pustular and Erythrodermic Disease
Generalized pustular and erythrodermic psoriasis can disrupt temperature, fluid, cardiovascular, metabolic, and infection defenses. Management begins with stabilization and phenotype confirmation, not an outpatient cream escalation.
- Generalized pustular psoriasis
- IL-36 receptor
- Spesolimab
- Erythroderma
- Withdrawal flare
- Supportive care
Fever, pain, diffuse pustules, erythroderma, fluid loss, and organ change demand escalation.
Temperature, circulation, fluids, electrolytes, infection, pain, and nutrition require active care.
Spesolimab provides labeled intravenous flare and subcutaneous between flare pathways.
Stabilize before narrowing the drug list
Assess temperature, hemodynamics, oxygenation, fluid and electrolyte status, renal and hepatic function, infection, pain, nutrition, and medication exposure. Obtain dermatology support urgently.
Identify triggers and mimics
Infection, pregnancy, hypocalcemia, medication changes, and abrupt withdrawal of systemic corticosteroids or other effective therapy can precipitate severe disease. Pustules require differentiation from infection and severe drug reactions.
Use spesolimab for GPP
Spesolimab is an IL-36 receptor antagonist labeled for generalized pustular psoriasis in adults and patients 12 years and older who weigh at least 40 kg. It treats flares intravenously and can be used subcutaneously when not experiencing a flare.
Use the current dosing boundary
A flare is treated with 900 mg intravenously over 90 minutes, with one additional 900 mg dose one week later if symptoms persist. When not in a flare, current labeling uses a 600 mg subcutaneous loading dose, then 300 mg four weeks later and every four weeks.
Plan beyond one infusion
Evaluate TB and vaccination status, infection, hypersensitivity, and neurologic symptoms. Other specialist options can include cyclosporine, infliximab, acitretin, methotrexate, or other pathway therapy based on phenotype, severity, prior response, and patient constraints.
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Lesson
Turn Response Into Durable Control
A treatment is successful only when disease burden falls, function returns, harm remains controlled, and the plan stays usable. Longitudinal care links targets, adherence, screening, vaccination, life stages, and switching decisions.
- Treatment target
- Vaccination
- Monitoring
- Pregnancy
- Adherence
- Switching
Skin activity, special sites, symptoms, joints, function, and quality of life define response.
Vaccines, infection, organs, mood, reproduction, and laboratory plans follow the exact treatment.
Efficacy, toxicity, access, preference, burden, and life changes justify deliberate transitions.
Set a measurable target
Document BSA or global assessment, special sites, symptoms, quality of life, joints, and photographs when helpful. Reassess on a timeline that fits the treatment and use shared goals such as clear or almost clear skin, minimal burden, and restored function.
Separate nonresponse from nonuse
Before switching, verify diagnosis, quantity, application, injection technique, schedule, access, storage, expectations, and whether the patient can follow the regimen. Secondary loss of response differs from never receiving adequate exposure.
Prevent avoidable immune risk
Complete age appropriate vaccines before immune modifying therapy when feasible. Avoid live vaccines with many systemic agents. Screen and monitor TB, hepatitis, infection, blood counts, liver, kidney, lipids, blood pressure, mood, or malignancy risk according to the exact treatment.
Plan reproductive care without legacy letters
Review pregnancy intention before teratogenic or immune modifying therapy. Methotrexate and acitretin have major reproductive restrictions. Narrowband UVB and selected biologics may be considered in coordinated specialist care, but decisions require current product and patient specific evidence.
Switch with a reason
Change treatment for inadequate efficacy, loss of response, toxicity, comorbidity, pregnancy planning, preference, access, or burden. Record the reason, washout or overlap plan, infection status, and the next measurement point.
Quick check
Module test
Check the connections.
Each attempt draws 10 questions from the complete 128 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.