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Psoriasis (and variants)

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Psoriasis (and variants)

Created: 01/12/2025 Last updated: 19/12/2025 Important: This content is for informational purposes only and is intended for healthcare professionals. It does not replace clinical assessment or medical judgment, does not establish a doctor-patient relationship, and does not constitute a standard of care. Medicine is rapidly evolving: always verify sources and use this information only as additional input for decision-making.

General

  • First Name: Psoriasis (vulgar, plaque psoriasis); variants: inverse/intertriginous, palmoplantar (hyperkeratotic and pustular), generalized pustular, erythrodermic, guttate, scalp, genital, nail. Kim Xnumx, Raharja 2021
  • History: Clinical entity recognized by Robert Willan at the beginning of the 19th century; named “psoriasis” by von Hebra in 1841. Psoriasis (PMC) 2014
  • EpidemiologyApproximate global prevalence 2–3%, with geographical variation (up to 8–11% in Nordic countries). Burden in 2019: ~40.8 million prevalent cases; similar incidence by sex. Paris 2020, Damiani 2021, Damiani 2021 (PubMed)
  • Códigos:
    • ICD-10: L40.0 psoriasis vulgaris; L40.1 generalized pustular; L40.2 acrodermatitis continua; L40.3 palmar and plantar pustulosis; L40.4 guttate; L40.5 arthropathic; L40.8 other; L40.9 unspecified. Ham 2020
    • ICD-11: Block EA90 (psoriasis); e.g., EA90.40 generalized pustular psoriasis. Puig 2024

 

  • Diagnostic checklist (ultra-concise):

    • Morphology (plaques/papules/pustules), distribution (extensor muscles, scalp, folds, palms/soles, genitals). Raharja 2021

    • Check nails and PEST /joint symptoms (pain, morning stiffness, dactylitis). Garshick 2021

    • Confirm triggers (streptococcus, medications, stress, tobacco). Chhabra 2022 , Brunasso 2021

    • Punch biopsy only if atypical/doubtful. Balan 2021

  • If systemic/biological plan : BH, PFH, renal PF, lipids, HBV/HCV/HIV , TB , pregnancy. Elmets 2021

  • Immune-mediated disease with axis IL-23/Th17/IL-17 central; interaction of genetic predisposition (HLA-C*06:02, IL23/IL23R, etc.) with triggers (streptococcal infections, drugs, trauma/Koebner, smoking —especially in palmoplantar—). Chhabra 2022, Kim Xnumx, Brunasso 2021
  • Elementary injury: Well-defined erythematous-squamous plaque (micaceous scale), variable pruritus. Kim Xnumx
  • SpacesExtensors (elbows/knees), scalp, lumbosacral region, intergluteal fold, nails; variants in folds, palms/soles, genital. Raharja 2021
  • Prototype: Symmetrical plates, Koebner phenomenon, Auspitz sign, Woronoff rings. Kim Xnumx
  • Clinical findings:
    • Ungueal: pitting, “oil drop” spots, onycholysis, subungual hyperkeratosis. Battista 2023, Hadeler 2021
    • Scalp: plates with a net boundary beyond the implantation line. Moscow 2021
    • genitalia: smooth erythema with minimal scaling; pain/itching, dyspareunia. Beck xnumx, Hong 2021
  • Evolution: Chronic-recurrent course, outbreaks associated with stress, infections (post-streptococcal guttate), drugs (β-blockers, lithium, anti-TNF). Kim Xnumx
  • Atypical forms/variants:
    • Guttate (Droplet papules following streptococcal pharyngitis; consider culture/ASO). Tsoi 2022

    • Inverse/intertriginous (smooth erythematous plaques, maceration; high confusion with candidiasis/ADC). Micali 2019

    • Palmoplantar : painful hyperkeratosis and/or pustulosis ; strong association with smoking. Heidemeyer 2023 , Brunasso 2021

    • Generalized pustular pustular pustule (GPP) : fever, malaise, diffuse sterile pustules; dermatological emergency. Puig 2024

    • Erythrodermic : erythema >90% BSA with thermal instability and risk of dehydration/infection. Singh 2016

  • Chronic eczema/DCA
  • Seborrheic dermatitis (especially on the scalp)
  • Ringworm (corporis/capitis)
  • Pityriasis rubra pilaris
  • Secondary syphilis
  • chronic lichen simplex
  • Candidiasis of skin folds
  • Dyshidrosis (pp)
  • Keratodermas
  • Contact dermatitis.
  • Boss: Psoriasiform dermatitis (regular acanthosis). Balan 2021
  • Key findingsHyper/parakeratosis with microabscesses of Munro and spongiform pustules of Kogoj; loss/thinning of granular layer; elongation of epidermal ridges “club-like”; thin suprapapillary plaques; dilated dermal capillaries; superficial lympho-neutrophilic infiltrate. Balan 2021
  • Staining/IF/IHQ: DIF generally negative; elevated K16/K17 keratins and proliferative index (Ki-67) but not routinely diagnostic. Tohyama 2019, Balan 2021
  • molecular testsNot required for psoriasis vulgaris; in GPP it can be considered IL36RN in family/child cases. Puig 2024

 

Psoriasis: It is characterized by hyperkeratosis (with parakeratosis), regular (psoriasiform) acanthosis and areas of hypogranulosis; with elongated epidermal clubs.

 

Psoriasis: Regular (psoriasiform) acanthosis (dotted line) with elongation of epidermal clubs (yellow arrow) and foci of parakeratosis (red arrow)

 

Psoriasis: Areas of hypogranulosis (blue arrow), with thinning of suprapapillary plates (yellow arrow) and dermal papillae with dilation of vascular plexuses (in this case of a discrete degree) (green circle)

 

  • Chronic eczematous dermatitis
  • Pityriasis rubra pilaris (checkerboard pattern)
  • Secondary syphilis (plasma cells)
  • chronic lichen simplex
  • Psoriasiform seborrheic dermatitis
  • Psoriasiform drug reactions.

  • Before systemic/biologic treatments : CBC (complete blood count), liver function tests, renal function tests, lipid profile (acitretin), HBsAg/anti-HBc/anti-HBs, anti-HCV, HIV; TB screening (IGRA or PPD) and chest X-ray as needed; β-HCG in women of childbearing potential. Elmets 2021 , Menter 2019

  • Guttata : throat culture/ASO if suggestive history. Tsoi 2022

  • Comorbidities : screening for psoriatic arthritis , metabolic syndrome, cardiovascular risk, mental health.

  • Biopsy:
    • Type: Punch 4–5 mm of active edge plate without recent topical treatment; include epidermis and superficial reticular dermis. Kimmel 2018, Balan 2021
    • ConsiderationsAvoid excoriated/infected areas; discontinue topical steroid for 1–2 weeks if possible; in pustular cases, sample recent pustules. Balan 2021
    • Contraindications: Relative (uncontrolled anticoagulation, untreated infection). Kimmel 2018
    • FixationFormalin 10% for H&E; fresh/saline medium for IFD if another concomitant blistering process is suspected. Kimmel 2018

First line (mild-moderate, non-special sites)

  • Topical : Corticosteroids (potency depending on the site) ± vitamin D analogues; a useful and safe combination. Elmets 2021 , Mosca 2021

  • Phototherapy : NB-UVB; PUVA in selected patients. Elmets 2021

  • special sites

    • Inversa/genital : Low- to medium- potency corticosteroids for short courses, calcineurin inhibitors (tacrolimus/pimecrolimus) as sparing agents; maceration/antecandidiasis care. Beck 2018 , Hong 2021 , Dattola 2018

    • Hyperkeratotic palmoplantar dermatitis : potent steroid with keratolytic agents (urea/salicylic acid) ± phototherapy; consider acitretin . Miceli 2023

    • Scalp : potent topical steroids/foams + calcipotriol; keratolytic shampoos. Fly 2021

    • Nail : intralesional triamcinolone (matrix), potent topicals/vitamin D; systemic if severe or with PsA. Hadeler 2021 , Battista 2023

Systemic (moderate-severe, refractory, special sites, comorbidity with PsA)

  • Non-biologics : Methotrexate , cyclosporine (short induction), acitretin , apremilast ; selection based on profile/objectives/contraindications. Elmets 2021

  • Biologicals (induction/maintenance):

    • Anti-TNF (infliximab, adalimumab, etanercept).

    • IL-12/23 (ustekinumab).

    • IL-17A/F or receptor (secukinumab, ixekizumab, brodalumab).

    • IL-23 p19 (guselkumab, Risankizumab, tildrakizumab).
      Comparative evidence (inductive, PASI90) favors IL-17/IL-23 about other classes. Menter 2019, Sbidian 2022, Armstrong 2021

  • New small molecules : Deucravacitinib (TYK2 inhibitor) approved for moderate-to-severe plaques (consider in biologic-naïve patients or as an oral alternative). Elmets 2021

    • Generalized pustular (GPP)

    • Supportive management + rapid control: cyclosporine, infliximab; spesolimab (anti-IL-36R) approved for outbreaks with rapid response. Puig 2024 , Bachelez 2021

  • Erythrodermic

    • Hospitalization, supportive care (fluids, temperature, infections), cyclosporine or infliximab as first-line treatment; consider IL-17/IL-23 if these fail or are contraindicated. Singh 2016 , Potestio 2023

Care/Safety

  • Methotrexate : hepatotoxicity, myelosuppression; avoid pregnancy/alcohol; monitor liver function tests/complete blood count. Elmets 2021

  • Acitretin : teratogenic (avoid pregnancy and prolonged contraception), dyslipidemia; liver function tests/lipids. Elmets 2021

  • Cyclosporine : nephrotoxicity/hypertension; creatinine/blood pressure. Elmets 2021

  • IL-17 : mucocutaneous candidiasis and risk/exacerbation of IBD in susceptible individuals. Eshwar 2022 , Feng 2022

  • Biologics in general : TB screening and surveillance before initiation; HBV/HCV; infections. Megna 2024 , Menter 2019

Key contraindications

  • Absolute contraindications : pregnancy (methotrexate, acitretin), severe liver disease (methotrexate), severe active infection (biologics). Elmets 2021

  • Relative contraindications : CKD (cyclosporine), IBD (IL-17 blockade), history of untreated TB (any biologic). Eshwar 2022 , Megna 2024

  • Fever, systemic malaise, diffuse pustules → suspected GPP (indication for urgent treatment). Bachelez 2021

  • Erythroderma (>90% TBSA), hypothermia/dehydration → hospitalize . Singh 2016

  • Start of biological testing : screening for TB, HBV, HCV, HIV , and updated vaccinations. Menter 2019

  • Pregnancy : Methotrexate/acitretin is contraindicated . Elmets 2021

  • IL-17 : Monitor for candidiasis and a history of IBD . Eshwar 2022

  • Screening for cardiovascular risk and mental health (depression/anxiety). Garshick 2021

  • Auspitz sign (pinpoint hemorrhage upon removal of scale) and Koebner sign (lesions in areas of trauma) support the diagnosis. Kim 2017

  • Nails with pitting/oily staining are very suggestive. Hadeler 2021

  • In skin folds/genitals , look for smooth, erythematous plaques with minimal scaling and rule out candidiasis. Hong 2021

  • Parisi R, et al. National, regional, and worldwide epidemiology of psoriasis. J Invest Dermatol . 2020;140(4):846–854. PMID: 32467098. DOI: 10.1016/j.jid.2019.08.032. Abstract: Global review with regional estimates and trends; confirms wide geographic variability in prevalence. PubMed

  • Damiani G, et al. The Global, Regional, and National Burden of Psoriasis. Front Med (Lausanne). 2021;8:743180. PMID: 34977058. DOI: 10.3389/fmed.2021.743180. Abstract: GBD 2019 analysis with incidence, prevalence, and DALYs; similar by sex; quantifies burdens per SDI. PubMed / PMC

  • Kim WB, et al. Diagnosis and management of psoriasis. Can Fam Physician . 2017;63(4):278–285. PMID: 28500197. Abstract: A pragmatic clinical review of presentation, diagnosis, and initial management. PMC

  • Raharja A, et al. Psoriasis: a brief overview. Clin Med (Lond). 2021;21(3):170–173. PMID: 34011518. DOI: 10.7861/clinmed.2021-0091. Abstract: Overview of clinical variants and general approach. PMC

  • Chhabra N, et al. Recent update on immunopathogenesis of psoriasis. Immunol Lett. 2022;244:1–8. PMID: 36272272. DOI: 10.1016/j.imlet.2022.10.004. Abstract: Current synthesis of the IL-23/Th17/IL-17 axis and emerging mediators. PMC

  • Balan S, et al. Histopathological approach to psoriasis. J Oral Maxillofac Pathol. 2021;25(3):367–372. PMID: 35059986. DOI: 10.4103/jomfp.JOMFP_291_21. Summary: Cardinal microscopic features (Munro/Kogoj, regular acanthosis, etc.). PMC

  • Park Y, et al. Histopathology of inflammatory skin diseases… Ann Dermatol. 2016;28(3):321–329. PMID: 27303187. DOI: 10.5021/ad.2016.28.3.321. Abstract: Psoriasiform histological differentials and practical criteria. PMC

  • Ham SP, et al. Validity of Diagnostic Codes… Ann Dermatol. 2020;32(2):139–146. PMID: 33911722. DOI: 10.5021/ad.2020.32.2.139. Abstract: Validates the use of ICD-10 codes L40.* and details clinical subcodes. PMC

  • Hong JJ, et al. Genital and inverse/intertriginous psoriasis. Dermatol Ther (Heidelberg). 2021;11(3):799–818. PMID: 33914293. DOI: 10.1007/s13555-021-00530-7. Abstract: Practical management and safety in sensitive areas. PMC

  • Beck KM, et al. Treatment of genital psoriasis: systematic review. Dermatol Ther (Heidelberg). 2018;8(4):509–525. PMID: 30145740. DOI: 10.1007/s13555-018-0262-1. Abstract: Evidence for topical and systemic treatments; low-potency steroids and calcineurin inhibitors. PMC

  • Sbidian E, et al. Systemic pharmacological treatments… Cochrane NMA. Cochrane Database Syst Rev. 2022;4:CD011535. PMID: 35603936. DOI: 10.1002/14651858.CD011535.pub5. Summary: IL-17/23 and infliximab superior in PASI90 (induction). PubMed

  • Menter A, et al. AAD-NPF guidelines: biologics. J Am Acad Dermatol. 2019;80(4):1029–1072. PMID: 30772098. DOI: 10.1016/j.jaad.2018.11.057. Abstract: Recommendations for the selection and monitoring of biologics. PubMed

  • Elmets CA, et al. AAD-NPF guidelines: non-biologic systemic antipsychotics. J Am Acad Dermatol. 2020;82(6):1445–1486. ​​PMID: 32738429. DOI: 10.1016/j.jaad.2020.02.044. Abstract: Safe use of methotrexate, cyclosporine, acitretin, apremilast, and phototherapy. PubMed

  • Puig L, et al. Delphi clinical consensus in GPP (includes ICD-11 EA90.40). J Eur Acad Dermatol Venereol. 2024;38(6):950–964. PMID: 38212927. DOI: 10.1111/jdv.19775. Abstract: Diagnostic/therapeutic algorithm and ICD-11 coding reference. PMC

  • Bachelez H, et al. Spesolimab in GPP (EFFISAYIL-1). N Engl J Med. 2021;385:2431–2440. PMID: 34936739. DOI: 10.1056/NEJMoa2111563. Abstract: Anti-IL-36R with rapid pustule clearance in GPP outbreaks. PubMed

  • Singh R.K., et al. Erythrodermic psoriasis: pathophysiology & current treatment. Am J Clin Dermatol. 2016;17(5):529–543. PMID: 27325435. DOI: 10.1007/s40257-016-0202-3. Summary: Recommends cyclosporine/infliximab in acute, acitretin/methotrexate in stable. PMC

  • Garshick MS, et al. Cardiovascular risk in psoriasis. Curr Atheroscler Rep. 2021;23(7):36. PMID: 33884549. DOI: 10.1007/s11883-021-00914-5. Abstract: Review of independent association with CV events and screening. PMC

  • Gelfand JM, et al. MI risk in psoriasis. JAMA . 2006;296:1735–1741. PMID: 17032986. DOI: 10.1001/jama.296.14.1735. Abstract: Increased risk of MI, especially in severe disease and young patients. PubMed

  • Micali G, et al. Inverse psoriasis: diagnosis to treatment. Clin Cosmet Investig Dermatol. 2019;12:953–965. PMID: 31908476. DOI: 10.2147/CCID.S197783. Abstract: Clinical features in skin folds and first-line therapies. PMC

  • Eshwar V, et al. Safety of IL-17A inhibitors. Drug Saf. 2022;45(12):1383–1398. PMID: 36197325. DOI: 10.1007/s40264-022-01243-5. Summary: Risk of candidiasis/RTIs and IBD considerations. PMC

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