Sections

Workup

Laboratory Studies

The diagnosis of psoriasis is almost always made on the basis of clinical findings. Laboratory investigations are rarely indicated. In severe cases, patients may have mild hyperuricemia and low folate levels, presumably because of enhanced epidermopoiesis.

Skin Biopsy

Skin biopsies can confirm the diagnosis of plaque psoriasis; however, this is usually reserved for the evaluation of atypical cases or for excluding other conditions in cases of diagnostic uncertainty. See Histologic Findings for more details on plaque histology.

Epidermis

Mitotic activity of basal keratinocytes is increased almost 50-fold, with keratinocytes migrating from the basal to the cornified layers in only 3-5 days rather than the normal 28-30 days. With hyperproliferation of skin cells, the epidermis becomes thickened or acanthotic in appearance and the rete ridges increase in size.

Abnormal keratinocyte differentiation is noted throughout the psoriatic plaques, as manifested by the loss of the granular layer. The stratum corneum is also thickened, and the retention of cell nuclei in this layer is referred to as parakeratosis.

Neutrophils and lymphocytes can be observed migrating upwards from the dermis into the acanthotic epidermis. Neutrophils may form localized collections known as Munro microabscesses. The presence of alternating collections of neutrophils sandwiched between layers of parakeratotic stratum corneum is virtually pathognomonic for psoriasis. (See image below.)

Plaque psoriasis. Photomicrograph of psoriasis. (1) Hyperkeratosis and parakeratosis, (2) neutrophils in the epidermis, (3) thinning of the epidermis overlying the dermal papillae, (4) vessels close to the epidermis, and (5) elongated rete ridges. Courtesy of Richard Crawford, MD, University of British Columbia, Department of Dermatology and Skin Science.

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Dermis

Signs of inflammation can be observed throughout the dermis in persons with plaque psoriasis. Marked hypervascularity and an increase in the size of the dermal papillae occur. An activated CD3⁺ lymphocytic infiltrate is noted around blood vessels, with T cells expressing cutaneous lymphocyte–associated antigen, co-stimulatory molecules such as CD2, and lymphocyte function-associated antigen–1 (LFA-1) adhesion molecules. An aggregation of neutrophils in the dermis occurs that extends up into the epidermis.

Treatment & Management

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Vena GA, Cassano N. Emerging drugs for psoriasis. Expert Opin Emerg Drugs. 2006 Nov. 11(4):567-96. [QxMD MEDLINE Link].
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Papp KA, Langley RG, Lebwohl M, Krueger GG, Szapary P, Yeilding N, et al. Efficacy and safety of ustekinumab, a human interleukin-12/23 monoclonal antibody, in patients with psoriasis: 52-week results from a randomised, double-blind, placebo-controlled trial (PHOENIX 2). Lancet. 2008 May 17. 371(9625):1675-84. [QxMD MEDLINE Link].
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Lebwohl M, Strober B, Menter A, Gordon K, Weglowska J, Puig L, et al. Phase 3 Studies Comparing Brodalumab with Ustekinumab in Psoriasis. N Engl J Med. 2015 Oct. 373 (14):1318-28. [QxMD MEDLINE Link]. [Full Text].
Reich K, Papp KA, Blauvelt A, Langley RG, Armstrong A, Warren RB, et al. Bimekizumab versus ustekinumab for the treatment of moderate to severe plaque psoriasis (BE VIVID): efficacy and safety from a 52-week, multicentre, double-blind, active comparator and placebo controlled phase 3 trial. Lancet. 2021 Feb 6. 397 (10273):487-498. [QxMD MEDLINE Link]. [Full Text].
Gordon KB, Foley P, Krueger JG, Pinter A, Reich K, Vender R, et al. Bimekizumab efficacy and safety in moderate to severe plaque psoriasis (BE READY): a multicentre, double-blind, placebo-controlled, randomised withdrawal phase 3 trial. Lancet. 2021 Feb 6. 397 (10273):475-486. [QxMD MEDLINE Link]. [Full Text].
Warren RB, Blauvelt A, Bagel J, Papp KA, Yamauchi P, Armstrong A, et al. Bimekizumab versus Adalimumab in Plaque Psoriasis. N Engl J Med. 2021 Jul 8. 385 (2):130-141. [QxMD MEDLINE Link]. [Full Text].
Wilson FC, Icen M, Crowson CS, McEvoy MT, Gabriel SE, Kremers HM. Incidence and clinical predictors of psoriatic arthritis in patients with psoriasis: a population-based study. Arthritis Rheum. 2009 Feb 15. 61(2):233-9. [QxMD MEDLINE Link].
Nickoloff BJ, Bonish BK, Marble DJ, Schriedel KA, DiPietro LA, Gordon KB, et al. Lessons learned from psoriatic plaques concerning mechanisms of tissue repair, remodeling, and inflammation. J Investig Dermatol Symp Proc. 2006 Sep. 11(1):16-29. [QxMD MEDLINE Link].
Boniface K, Blom B, Liu YJ, de Waal Malefyt R. From interleukin-23 to T-helper 17 cells: human T-helper cell differentiation revisited. Immunol Rev. 2008 Dec. 226:132-46. [QxMD MEDLINE Link].
Sterry W, Strober BE, Menter A. Obesity in psoriasis: the metabolic, clinical and therapeutic implications. Report of an interdisciplinary conference and review. Br J Dermatol. 2007 Oct. 157(4):649-55. [QxMD MEDLINE Link].
Lé AM, Torres T. New Topical Therapies for Psoriasis. Am J Clin Dermatol. 2022 Jan. 23 (1):13-24. [QxMD MEDLINE Link].
Calzavara-Pinton P, Leone G, Venturini M, Sala R, Colombo D, La Parola IL, et al. A comparative non randomized study of narrow-band (NB) (312 +/- 2 nm) UVB phototherapy versus sequential therapy with oral administration of low-dose Cyclosporin A and NB-UVB phototherapy in patients with severe psoriasis vulgaris. Eur J Dermatol. 2005 Nov-Dec. 15(6):470-3. [QxMD MEDLINE Link].
Calzavara-Pinton PG, Sala R, Arisi M, Rossi MT, Venturini M, Ortel B. Synergism between narrowband ultraviolet B phototherapy and etanercept for the treatment of plaque-type psoriasis. Br J Dermatol. 2013 Jul. 169(1):130-6. [QxMD MEDLINE Link].
Lebwohl MG, Kircik L, Callis Duffin K, Pariser D, Hooper M, Wenkert D, et al. A randomized study to evaluate the efficacy and safety of adding topical therapy to etanercept in patients with moderate to severe plaque psoriasis. J Am Acad Dermatol. 2013 May 1. [QxMD MEDLINE Link].
Armstrong AW, Gooderham M, Warren RB, Papp KA, Strober B, Thaçi D, et al. Deucravacitinib versus placebo and apremilast in moderate to severe plaque psoriasis: efficacy and safety results from the 52-week, randomized, double-blinded, placebo-controlled phase 3 POETYK PSO-1 trial. J Am Acad Dermatol. 2022 Jul 9. [QxMD MEDLINE Link]. [Full Text].
Langley RG, Elewski BE, Lebwohl M, Reich K, Griffiths CE, Papp K, et al. Secukinumab in plaque psoriasis--results of two phase 3 trials. N Engl J Med. 2014 Jul 24. 371(4):326-38. [QxMD MEDLINE Link]. [Full Text].
Gordon KB, Strober B, Lebwohl M, Augustin M, Blauvelt A, Poulin Y, et al. Efficacy and safety of risankizumab in moderate-to-severe plaque psoriasis (UltIMMa-1 and UltIMMa-2): results from two double-blind, randomised, placebo-controlled and ustekinumab-controlled phase 3 trials. Lancet. 2018 Aug 25. 392 (10148):650-661. [QxMD MEDLINE Link].
Menter A, Cather JC, Baker D, Farber HF, Lebwohl M, Darif M. The efficacy of multiple courses of alefacept in patients with moderate to severe chronic plaque psoriasis. J Am Acad Dermatol. 2006 Jan. 54(1):61-3. [QxMD MEDLINE Link].
Krueger GG, Langley RG, Finlay AY, Griffiths CE, Woolley JM, Lalla D, et al. Patient-reported outcomes of psoriasis improvement with etanercept therapy: results of a randomized phase III trial. Br J Dermatol. 2005 Dec. 153(6):1192-9. [QxMD MEDLINE Link].
Sukal SA, Nadiminti L, Granstein RD. Etanercept and demyelinating disease in a patient with psoriasis. J Am Acad Dermatol. 2006 Jan. 54(1):160-4. [QxMD MEDLINE Link].
Wong VK, Lebwohl MG. Treatment of psoriatic arthritis with etanercept, a tumour necrosis factor antagonist. Expert Opin Biol Ther. 2005 Nov. 5(11):1505-13. [QxMD MEDLINE Link].
Paller AS, Siegfried EC, Eichenfield LF, Pariser D, Langley RG, Creamer K, et al. Long-term etanercept in pediatric patients with plaque psoriasis. J Am Acad Dermatol. 2010 Nov. 63(5):762-8. [QxMD MEDLINE Link].
Menter A, Gordon KB, Leonardi CL, Gu Y, Goldblum OM. Efficacy and safety of adalimumab across subgroups of patients with moderate to severe psoriasis. J Am Acad Dermatol. 2010 Sep. 63(3):448-56. [QxMD MEDLINE Link].
Langley RG, Feldman SR, Han C, Schenkel B, Szapary P, Hsu MC, et al. Ustekinumab significantly improves symptoms of anxiety, depression, and skin-related quality of life in patients with moderate-to-severe psoriasis: Results from a randomized, double-blind, placebo-controlled phase III trial. J Am Acad Dermatol. 2010 Sep. 63(3):457-65. [QxMD MEDLINE Link].
National Institute for Health and Clinical Excellence (NICE). Adalimumab for the treatment of adults with psoriasis. National Guidelines Clearinghouse. Jun 2008.
National Institute for Health and Clinical Excellence (NICE). Infliximab for the treatment of adults with psoriasis. National Guidelines Clearinghouse. Jan 2008.
Lebwohl MG, Kircik L, Callis Duffin K, Pariser D, Hooper M, Wenkert D, et al. A randomized study to evaluate the efficacy and safety of adding topical therapy to etanercept in patients with moderate to severe plaque psoriasis. J Am Acad Dermatol. 2013 May 1. [QxMD MEDLINE Link].
Vender R, Lynde C, Gilbert M, Ho V, Sapra S, Poulin-Costello M. One-Year, Multicenter, Open-Label, Single-Arm Study Evaluating the Safety and Effectiveness of Etanercept for the Treatment of Moderate-to-Severe Plaque Psoriasis in a Canadian Population. J Cutan Med Surg. 2013 Mar-Apr. 17(2):129-38. [QxMD MEDLINE Link].
Reich K, Wozel G, Zheng H, van Hoogstraten HJ, Flint L. Efficacy and Safety of Infliximab as Continuous or Intermittent Therapy in Patients With Moderate-to-Severe Plaque Psoriasis: Results of a Randomised, Long-Term Extension Trial (RESTORE2). Br J Dermatol. 2013 Apr 29. [QxMD MEDLINE Link].
Mease PJ, Reich K. Alefacept with methotrexate for treatment of psoriatic arthritis: open-label extension of a randomized, double-blind, placebo-controlled study. J Am Acad Dermatol. 2009 Mar. 60(3):402-11. [QxMD MEDLINE Link].
Leonardi C, Langley RG, Papp K, Tyring SK, Wasel N, Vender R, et al. Adalimumab for Treatment of Moderate to Severe Chronic Plaque Psoriasis of the Hands and Feet: Efficacy and Safety Results From REACH, a Randomized, Placebo-Controlled, Double-blind Trial. Arch Dermatol. 2010 Dec 20. [QxMD MEDLINE Link].
Brown T. Fingernail Psoriasis Data Added to Humira Prescribing Info. Medscape News & Perspective. Available at http://www.medscape.com/viewarticle/877985?src=soc_fb_170405_mscpedt_news_pharm_humira. March 30, 2017; Accessed: April 6, 2017.
Lebwohl M, Blauvelt A, Paul C, Sofen H, Węgłowska J, Piguet V, et al. Certolizumab Pegol for the Treatment of Chronic Plaque Psoriasis: Results Through 48 Weeks of a Phase 3, Multicenter, Randomized, Double-Blinded, Etanercept- and Placebo-Controlled Study (CIMPACT). J Am Acad Dermatol. 2018 Apr 13. [QxMD MEDLINE Link].
Gottlieb AB, Blauvelt A, Thaçi D, Leonardi CL, Poulin Y, Drew J, et al. Certolizumab Pegol for the Treatment of Chronic Plaque Psoriasis: Results through 48 Weeks from Two Phase 3, Multicenter, Randomized, Double-Blinded, Placebo-Controlled Studies (CIMPASI-1 and CIMPASI-2). J Am Acad Dermatol. 2018 Apr 13. [QxMD MEDLINE Link].
Young MS, Horn EJ, Cather JC. The ACCEPT study: ustekinumab versus etanercept in moderate-to-severe psoriasis patients. Expert Rev Clin Immunol. 2011 Jan. 7 (1):9-13. [QxMD MEDLINE Link]. [Full Text].
Landells I, Marano C, Hsu MC, Li S, Zhu Y, Eichenfield LF, et al. Ustekinumab in adolescent patients age 12 to 17 years with moderate-to-severe plaque psoriasis: results of the randomized phase 3 CADMUS study. J Am Acad Dermatol. 2015 Oct. 73 (4):594-603. [QxMD MEDLINE Link]. [Full Text].
Blauvelt A, Papp KA, Griffiths CE, Randazzo B, Wasfi Y, Shen YK, et al. Efficacy and safety of guselkumab, an anti-interleukin-23 monoclonal antibody, compared with adalimumab for the continuous treatment of patients with moderate to severe psoriasis: Results from the phase III, double-blinded, placebo- and active comparator-controlled VOYAGE 1 trial. J Am Acad Dermatol. 2017 Mar. 76 (3):405-417. [QxMD MEDLINE Link]. [Full Text].
Reich K, Armstrong AW, Foley P, Song M, Wasfi Y, Randazzo B, et al. Efficacy and safety of guselkumab, an anti-interleukin-23 monoclonal antibody, compared with adalimumab for the treatment of patients with moderate to severe psoriasis with randomized withdrawal and retreatment: Results from the phase III, double-blind, placebo- and active comparator-controlled VOYAGE 2 trial. J Am Acad Dermatol. 2017 Mar. 76 (3):418-431. [QxMD MEDLINE Link]. [Full Text].
Langley RG, Tsai TF, Flavin S, Song M, Randazzo B, Wasfi Y, et al. Efficacy and safety of guselkumab in patients with psoriasis who have an inadequate response to ustekinumab: Results of the randomized, double-blind, Phase 3 NAVIGATE trial. Br J Dermatol. 2017 Jun 21. [QxMD MEDLINE Link].
Reich K, Papp KA, Blauvelt A, Tyring SK, Sinclair R, Thaçi D, et al. Tildrakizumab versus placebo or etanercept for chronic plaque psoriasis (reSURFACE 1 and reSURFACE 2): results from two randomised controlled, phase 3 trials. Lancet. 2017 Jul 15. 390 (10091):276-288. [QxMD MEDLINE Link].
Saunte DM, Mrowietz U, Puig L, Zachariae C. Candida infections in psoriasis and psoriatic arthritis patients treated with IL-17 inhibitors and their practical management. Br J Dermatol. 2016 Aug 31. [QxMD MEDLINE Link].
Friedewald VE, Cather JC, Gelfand JM, Gordon KB, Gibbons GH, Grundy SM, et al. AJC editor's consensus: psoriasis and coronary artery disease. Am J Cardiol. 2008 Dec 15. 102(12):1631-43. [QxMD MEDLINE Link].
[Guideline] American Academy of Dermatology. Section 1. Overview of psoriasis and guidelines of carefor the treatment of psoriasis with biologics. Available at https://www.aad.org/File%20Library/Global%20navigation/Education%20and%20quality%20care/Guidelines-psoriarsis-sec-1.pdf. Accessed: October 11, 2017.
[Guideline] American Academy of Dermatology. Section 2. Psoriatic arthritis: Overview and guidelines of carefor treatment with an emphasis on the biologics. Available at https://www.aad.org/File%20Library/Global%20navigation/Education%20and%20quality%20care/Guidelines-psoriasis-sec-2.pdf. Accessed: October 11, 2017.
[Guideline] American Academy of Dermatology. Section 3. Guidelines of care for the management and treatmentof psoriasis with topical therapies. Available at https://www.aad.org/File%20Library/Global%20navigation/Education%20and%20quality%20care/Guidelines-psoriasis-sec-3.pdf. Accessed: October 11, 2017.
[Guideline] American Academy of Dermatology. Section 4. Guidelines of care for the management and treatment ofpsoriasis with traditional systemic agents. Available at https://www.aad.org/File%20Library/Global%20navigation/Education%20and%20quality%20care/Guidelines-psoriasis-sec-4.pdf. Accessed: October 11, 2017.
[Guideline] American Academy of Dermatology. Section 5. Guidelines of care for the treatment of psoriasis withphototherapy and photochemotherapy. Available at https://www.aad.org/File%20Library/Global%20navigation/Education%20and%20quality%20care/Guidelines-psoriasis-sec-5.pdf. Accessed: October 11, 2017.
[Guideline] American Academy of Dermatology. Section 6. Guidelines of care for the treatment of psoriasis and psoriatic arthritis: Case-based presentations and evidence-basedconclusions. Available at https://www.aad.org/File%20Library/Global%20navigation/Education%20and%20quality%20care/section6-psoriasis-guideline.pdf. Accessed: October 11, 2017.
[Guideline] Elmets CA, Korman NJ, Prater EF, et al. Joint AAD-NPF Guidelines of care for the management and treatment of psoriasis with topical therapy and alternative medicine modalities for psoriasis severity measures. J Am Acad Dermatol. 2021 Feb. 84 (2):432-470. [QxMD MEDLINE Link].
[Guideline] Smith CH, Jabbar-Lopez ZK, Yiu ZZ, Bale T, Burden AD, Coates LC, et al. British Association of Dermatologists guidelines for biologic therapy for psoriasis 2017. Br J Dermatol. 2017 Sep. 177 (3):628-636. [QxMD MEDLINE Link].
[Guideline] Menter A, Strober BE, Kaplan DH, et al. Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with biologics. J Am Acad Dermatol. 2019 Feb 13. [QxMD MEDLINE Link].
[Guideline] Elmets CA, Lim HW, Stoff B, et al. Joint American Academy of Dermatology-National Psoriasis Foundation guidelines of care for the management and treatment of psoriasis with phototherapy. J Am Acad Dermatol. 2019 Sep. 81 (3):775-804. [QxMD MEDLINE Link]. [Full Text].
Lebwohl MG, Stein Gold L, Strober B, Papp KA, Armstrong AW, Bagel J, et al. Phase 3 Trials of Tapinarof Cream for Plaque Psoriasis. N Engl J Med. 2021 Dec 9. 385 (24):2219-2229. [QxMD MEDLINE Link]. [Full Text].

Media Gallery

Plaque psoriasis. Courtesy of University of British Columbia, Department of Dermatology and Skin Science.
Plaque psoriasis. Courtesy of University of British Columbia, Department of Dermatology and Skin Science.
Plaque psoriasis. Photomicrograph of psoriasis. (1) Hyperkeratosis and parakeratosis, (2) neutrophils in the epidermis, (3) thinning of the epidermis overlying the dermal papillae, (4) vessels close to the epidermis, and (5) elongated rete ridges. Courtesy of Richard Crawford, MD, University of British Columbia, Department of Dermatology and Skin Science.

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Author

Harvey Lui, MD, FRCPC Professor and Head, Department of Dermatology and Skin Science, Vancouver General Hospital, University of British Columbia; Medical Director, The Skin Centre, Lions Laser Skin Centre and Psoriasis and Phototherapy Clinic, Vancouver General Hospital

Harvey Lui, MD, FRCPC is a member of the following medical societies: Canadian Medical Association, American Society for Photobiology, Photomedicine Society, European Academy of Dermatology and Venereology, National Psoriasis Foundation, Canadian Dermatology Association, College of Physicians and Surgeons of British Columbia, North American Hair Research Society, Canadian Dermatology Foundation, American Academy of Dermatology, American Society for Laser Medicine and Surgery

Disclosure: Received consulting fee from Astellas for review panel membership; Received consulting fee from Amgen/Wyeth for speaking and teaching; Received honoraria from LEO Pharma for speaking and teaching; Received grant/research funds from LEO Pharma for investigator; Received grant/research funds from Galderma for other.

Coauthor(s)

Adam J Mamelak, MD, FRCPC Attending Physician, Division of Dermatology, The Ottawa Hospital, University of Ottawa

Adam J Mamelak, MD, FRCPC is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Surgery, American Society for Dermatologic Surgery, Canadian Dermatology Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Richard P Vinson, MD Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA

Richard P Vinson, MD is a member of the following medical societies: American Academy of Dermatology, Texas Medical Association, Association of Military Dermatologists, Texas Dermatological Society

Disclosure: Nothing to disclose.

Christen M Mowad, MD Professor, Department of Dermatology, Geisinger Medical Center

Christen M Mowad, MD is a member of the following medical societies: Alpha Omega Alpha, Noah Worcester Dermatological Society, Pennsylvania Academy of Dermatology, American Academy of Dermatology, Phi Beta Kappa

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Additional Contributors

Mark G Lebwohl, MD Chairman, Department of Dermatology, Mount Sinai School of Medicine

Mark G Lebwohl, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Received none from Amgen for consultant & investigator; Received none from Novartis for consultant & investigator; Received none from Pfizer for consultant & investigator; Received none from Celgene Corporation for consultant & investigator; Received none from Clinuvel for consultant & investigator; Received none from Eli Lilly & Co. for consultant & investigator; Received none from Janssen Ortho Biotech for consultant & investigator; Received none from LEO Pharmaceuticals for consultant & inves.

Plaque Psoriasis Workup

Laboratory Studies

Skin Biopsy

Histologic Findings

Epidermis

Dermis

References

Tables

Contributor Information and Disclosures

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