- Author: Jeffrey Meffert, MD; Chief Editor: William D James, MD more...
The diagnosis of psoriasis is clinical. The differentiation of psoriatic arthritis from rheumatoid arthritis and gout can be facilitated by the absence of the typical laboratory findings of those conditions. Overlap with other arthritic syndromes is possible, however.
Laboratory studies and findings for patients with psoriasis may include the following:
- Test result for rheumatoid factor (RF) is negative.
- Erythrocyte sedimentation rate (ESR) is usually normal (except in pustular and erythrodermic psoriasis).
- Uric acid level may be elevated in psoriasis (especially in pustular psoriasis), causing confusion with gout in psoriatic arthritis.
- Fluid from pustules is sterile with neutrophilic infiltrate.
- Perform fungal studies. (This is especially important in cases of hand and foot psoriasis that seem to be worsening with the use of topical steroids.)
If starting systemic therapies such as immunological inhibitors, consider obtaining baseline laboratory studies (ie, complete blood count [CBC], blood urea nitrogen [BUN]/creatinine, liver function tests [LFTs], hepatitis panel, tuberculosis [TB] screening).
Although most cases of psoriasis are diagnosed clinically, some, particularly the pustular forms, can be difficult to recognize. In these cases, dermatologic biopsy can be used to make diagnosis. Biopsy of the skin lesion may reveal basal cell hyperplasia, proliferation of subepidermal vasculature, absence of normal cell maturation, and keratinization. A large number of activated T cells are present in the epidermis. Biopsy of acral skin may be less useful as chronic eczematous dermatitis may be psoriasiform and psoriasis of the palms and soles may show spongiosis more often associated with eczema.
Radiographs of affected joints can be helpful in differentiating types of arthritis. Joint x-rays can facilitate the diagnosis of psoriatic arthritis. Bone scans can identify joint involvement early.
Conjunctival impression cytology has demonstrated an increased incidence of squamous metaplasia, neutrophil clumping, and snakelike chromatin.
When the scales are removed, small droplets of blood appear within a few seconds from exposed vessels in the dermal papillae; this is known as the Auspitz sign.
Huynh N, Cervantes-Castaneda RA, Bhat P, Gallagher MJ, Foster CS. Biologic response modifier therapy for psoriatic ocular inflammatory disease. Ocul Immunol Inflamm. 2008 May-Jun. 16(3):89-93. [Medline].
[Guideline] Menter A, Korman NJ, Elmets CA, Feldman SR, Gelfand JM, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: section 4. Guidelines of care for the management and treatment of psoriasis with traditional systemic agents. J Am Acad Dermatol. 2009 Sep. 61(3):451-85. [Medline].
Mrowietz U, de Jong EM, Kragballe K, Langley R, Nast A, Puig L, et al. A consensus report on appropriate treatment optimization and transitioning in the management of moderate-to-severe plaque psoriasis. J Eur Acad Dermatol Venereol. 2013 Feb 26. [Medline].
Gulliver W. Long-term prognosis in patients with psoriasis. Br J Dermatol. 2008 Aug. 159 Suppl 2:2-9. [Medline].
Keaney TC, Kirsner RS. New insights into the mechanism of narrow-band UVB therapy for psoriasis. J Invest Dermatol. 2010 Nov. 130(11):2534. [Medline].
Pietrzak AT, Zalewska A, Chodorowska G, Krasowska D, Michalak-Stoma A, Nockowski P, et al. Cytokines and anticytokines in psoriasis. Clin Chim Acta. 2008 Aug. 394(1-2):7-21. [Medline].
Keller JJ, Lin HC. The Effects of Chronic Periodontitis and Its Treatment on the Subsequent Risk of Psoriasis. Br J Dermatol. 2012 Jul 3. [Medline].
Riveira-Munoz E, He SM, Escaramís G, et al. Meta-Analysis Confirms the LCE3C_LCE3B Deletion as a Risk Factor for Psoriasis in Several Ethnic Groups and Finds Interaction with HLA-Cw6. J Invest Dermatol. 2011 May. 131(5):1105-9. [Medline].
Gelfand JM, Stern RS, Nijsten T, Feldman SR, Thomas J, Kist J, et al. The prevalence of psoriasis in African Americans: results from a population-based study. J Am Acad Dermatol. 2005 Jan. 52(1):23-6. [Medline].
Klufas DM, Wald JM, Strober BE. Treatment of Moderate to Severe Pediatric Psoriasis: A Retrospective Case Series. Pediatr Dermatol. 2016 Feb 12. [Medline].
Gelfand JM, Troxel AB, Lewis JD, Kurd SK, Shin DB, Wang X, et al. The risk of mortality in patients with psoriasis: results from a population-based study. Arch Dermatol. 2007 Dec. 143(12):1493-9. [Medline].
Harding A. Extent of psoriasis tied to risk of comorbidities. Reuters Health Information. August 15, 2013. [Full Text].
Yeung H, Takeshita J, Mehta NN, et al. Psoriasis Severity and the Prevalence of Major Medical Comorbidity: A Population-Based Study. JAMA Dermatol. 2013 Aug 7. [Medline].
Patel RV, Shelling ML, Prodanovich S, Federman DG, Kirsner RS. Psoriasis and vascular disease-risk factors and outcomes: a systematic review of the literature. J Gen Intern Med. 2011 Sep. 26(9):1036-49. [Medline].
Li WQ, Han JL, Manson JE, Rimm EB, Rexrode KM, Curhan GC, et al. Psoriasis and risk of nonfatal cardiovascular disease in U.S. women: a cohort study. Br J Dermatol. 2012 Apr. 166(4):811-8. [Medline].
Henderson D. Psoriasis severity linked to uncontrolled hypertension. Medscape Medical News. October 27, 2014. [Full Text].
Takeshita J, Wang S, Shin DB, Mehta NN, Kimmel SE, Margolis DJ, et al. Effect of Psoriasis Severity on Hypertension Control: A Population-Based Study in the United Kingdom. JAMA Dermatol. 2014 Oct 15. [Medline].
Wan J, Wang S, Haynes K, Denburg MR, Shin DB, Gelfand JM. Risk of moderate to advanced kidney disease in patients with psoriasis: population based cohort study. BMJ. 2013 Oct 15. 347:f5961. [Medline].
Laidman J. Moderate and Severe Psoriasis Linked to Higher Kidney Risks. Medscape [serial online]. Available at http://www.medscape.com/viewarticle/812730. Accessed: October 21, 2013.
Kurd SK, Troxel AB, Crits-Christoph P, Gelfand JM. The risk of depression, anxiety, and suicidality in patients with psoriasis: a population-based cohort study. Arch Dermatol. 2010 Aug. 146(8):891-5. [Medline]. [Full Text].
Oostveen AM, de Jager ME, van de Kerkhof PC, Donders AR, de Jong EM, Seyger MM. The influence of treatments in daily clinical practice on the Children's Dermatology Life Quality Index in juvenile psoriasis: a longitudinal study from the Child-CAPTURE patient registry. Br J Dermatol. 2012 May 23. [Medline].
Lucka TC, Pathirana D, Sammain A, Bachmann F, Rosumeck S, Erdmann R, et al. Efficacy of systemic therapies for moderate-to-severe psoriasis: a systematic review and meta-analysis of long-term treatment. J Eur Acad Dermatol Venereol. 2012 Mar 9. [Medline].
Pettey AA, Balkrishnan R, Rapp SR, Fleischer AB, Feldman SR. Patients with palmoplantar psoriasis have more physical disability and discomfort than patients with other forms of psoriasis: implications for clinical practice. J Am Acad Dermatol. 2003 Aug. 49(2):271-5. [Medline].
Sampogna F, Tabolli S, Soderfeldt B, Axtelius B, Aparo U, Abeni D. Measuring quality of life of patients with different clinical types of psoriasis using the SF-36. Br J Dermatol. 2006 May. 154(5):844-9. [Medline].
Langenbruch A, Radtke MA, Krensel M, Jacobi A, Reich K, Augustin M. Nail involvement as a predictor of concomitant psoriatic arthritis in patients with psoriasis. Br J Dermatol. 2014 Nov. 171(5):1123-8. [Medline].
Moadel K, Perry HD, Donnenfeld ED, Zagelbaum B, Ingraham HJ. Psoriatic corneal abscess. Am J Ophthalmol. 1995 Jun. 119(6):800-1. [Medline].
Durrani K, Foster CS. Psoriatic uveitis: a distinct clinical entity?. Am J Ophthalmol. 2005 Jan. 139(1):106-11. [Medline].
Takahashi H, Sugita S, Shimizu N, Mochizuki M. A high viral load of Epstein-Barr virus DNA in ocular fluids in an HLA-B27-negative acute anterior uveitis patient with psoriasis. Jpn J Ophthalmol. 2008 Mar-Apr. 52(2):136-8. [Medline].
[Guideline] Menter A, Gottlieb A, Feldman SR, Van Voorhees AS, Leonardi CL, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: Section 1. Overview of psoriasis and guidelines of care for the treatment of psoriasis with biologics. J Am Acad Dermatol. 2008 May. 58(5):826-50. [Medline].
[Guideline] Menter A, Korman NJ, Elmets CA, Feldman SR, Gelfand JM, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis. Section 3. Guidelines of care for the management and treatment of psoriasis with topical therapies. J Am Acad Dermatol. 2009 Apr. 60(4):643-59. [Medline].
[Guideline] Menter A, Korman NJ, Elmets CA, Feldman SR, Gelfand JM, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: Section 5. Guidelines of care for the treatment of psoriasis with phototherapy and photochemotherapy. J Am Acad Dermatol. 2010 Jan. 62(1):114-35. [Medline].
[Guideline] Menter A, Korman NJ, Elmets CA, Feldman SR, Gelfand JM, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis Section 6. Guidelines of care for the treatment of psoriasis and psoriatic arthritis: Case-based presentations and evidence-based conclusions. J Am Acad Dermatol. 2011 Feb 7. [Medline].
Mason AR, Mason J, Cork M, Dooley G, Edwards G. Topical treatments for chronic plaque psoriasis. Cochrane Database Syst Rev. 2009 Apr 15. CD005028. [Medline].
Stern RS. The risk of squamous cell and basal cell cancer associated with psoralen and ultraviolet A therapy: A 30-year prospective study. J Am Acad Dermatol. 2012 Jan 18. [Medline].
Carrascosa JM, Plana A, Ferrandiz C. Effectiveness and Safety of Psoralen-UVA (PUVA) Topical Therapy in Palmoplantar Psoriasis: A Report on 48 Patients. Actas Dermosifiliogr. 2013 Mar 6. [Medline].
Mehta D, Lim HW. Ultraviolet B Phototherapy for Psoriasis: Review of Practical Guidelines. Am J Clin Dermatol. 2016 Feb 12. [Medline].
Stern DK, Creasey AA, Quijije J, Lebwohl MG. UV-A and UV-B Penetration of Normal Human Cadaveric Fingernail Plate. Arch Dermatol. 2011 Apr. 147(4):439-41. [Medline].
Mantovani A, Gisondi P, Lonardo A, Targher G. Relationship between Non-Alcoholic Fatty Liver Disease and Psoriasis: A Novel Hepato-Dermal Axis?. Int J Mol Sci. 2016 Feb 5. 17 (2):[Medline].
Salvi M, Macaluso L, Luci C, Mattozzi C, Paolino G, Aprea Y, et al. Safety and efficacy of anti-tumor necrosis factors α in patients with psoriasis and chronic hepatitis C. World J Clin Cases. 2016 Feb 16. 4 (2):49-55. [Medline].
Komrokji RS, Kulasekararaj A, Al Ali NH, Kordasti S, Bart-Smith E, Craig BM, et al. Autoimmune Diseases and Myelodysplastic Syndromes. Am J Hematol. 2016 Feb 13. [Medline].
Sorensen EP, Algzlan H, Au SC, Garber C, Fanucci K, Nguyen MB, et al. Lower Socioeconomic Status is Associated With Decreased Therapeutic Response to the Biologic Agents in Psoriasis Patients. J Drugs Dermatol. 2016 Feb 1. 15 (2):147-53. [Medline].
Castaldo G, Galdo G, Rotondi Aufiero F, Cereda E. Very low-calorie ketogenic diet may allow restoring response to systemic therapy in relapsing plaque psoriasis. Obes Res Clin Pract. 2015 Nov 8. [Medline].
Barrea L, Balato N, Di Somma C, Macchia PE, Napolitano M, Savanelli MC, et al. Nutrition and psoriasis: is there any association between the severity of the disease and adherence to the Mediterranean diet?. J Transl Med. 2015 Jan 27. 13:18. [Medline].
Millsop JW, Bhatia BK, Debbaneh M, Koo J, Liao W. Diet and psoriasis, part III: role of nutritional supplements. J Am Acad Dermatol. 2014 Sep. 71 (3):561-9. [Medline].
Finamor DC, Sinigaglia-Coimbra R, Neves LC, Gutierrez M, Silva JJ, Torres LD, et al. A pilot study assessing the effect of prolonged administration of high daily doses of vitamin D on the clinical course of vitiligo and psoriasis. Dermatoendocrinol. 2013 Jan 1. 5 (1):222-34. [Medline].
Kui R, Gál B, Gaál M, Kiss M, Kemény L, Gyulai R. Presence of antidrug antibodies correlates inversely with the plasma tumor necrosis factor (TNF)-α level and the efficacy of TNF-inhibitor therapy in psoriasis. J Dermatol. 2016 Feb 19. [Medline].
Papp KA, Griffiths CE, Gordon K, Lebwohl M, et al. Long-term safety of ustekinumab in patients with moderate-to-severe psoriasis: final results from five years of follow-up. Br J Dermatol. 2013 Jan 10. [Medline].
Kimball AB, Gordon KB, Fakharzadeh S, Yeilding N, Szapary PO, Schenkel B, et al. Long-term efficacy of ustekinumab in patients with moderate-to-severe psoriasis: results from the PHOENIX 1 trial through up to 3 years. Br J Dermatol. 2012 Feb 22. [Medline].
Di Lernia V, Bardazzi F. Profile of tofacitinib citrate and its potential in the treatment of moderate-to-severe chronic plaque psoriasis. Drug Des Devel Ther. 2016. 10:533-9. [Medline].