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Friday 14 November 2003

cutaneous psoriasis


Definition : Psoriasis is a chronic relapsing condition affecting skin, nails and joints that most commonly presents with well demarcated erythematous papules and plaques with silvery white scales.


L40 - Psoriasis
L40.0 - psoriasis vulgaris
L40.1 - generalized pustular psoriasis
L40.2 - acrodermatitis continua
L40.3 - pustulosis palmaris et plantaris
L40.4 - guttate psoriasis
L40.5 - arthropathic psoriasis
L40.8 - other psoriasis
L40.9 - psoriasis, unspecified


- neutrophils in stratum corneum in psoriasis, vs. pustule of Kogoj in stratum spinosum

- cutaneous psoriasis


The biopsy shows psoriasis, based on these findings:
- parakeratosis
- club shaped rete ridges
- absent granular layer / hypogranulosis
- acanthosis (hyperplasia / overgrowth of the epidermis)

  • most prominent at the rete ridges,

- dermal chronic inflammation / chronic dermatitis

  • prominent capillaries
  • vascular congestion of papillary dermis

- neutrophils in the parakeratotic epidermis

- psoriasis

The patient frequently has a scaly, silver rash.

A major clue to psoriasis is parakeratosis with an ABSENT GRANULAR LAYER. Other findings include prominent rete ridges, prominent dermal capillaries and inflammation, and Munro microabscesses - neutrophils in the parakeratotic epidermis.

-  epidermal anomalies in psoriais
- ungueal anomalies in psoriasis


- guttate psoriasis / eruptive psoriasis
- pustular psoriasis
- ungueal psoriasis

  • seen in up to 50% of psoriasis patients, more common in patients with psoriatic arthropathy
  • psoriasiform onychitis with spongiform pustulation, negative fungal special stains
  • differential : onychomycosis , eczematous onychitis , Reiter syndrome

Susceptibility loci

- PSORS1 locus at 6p21 (12148091)
- IL12B variants (17236132)
- IL23R variants (17236132)


- Schon MP, Boehncke WH. Psoriasis. N Engl J Med. 2005 May 5;352(18):1899-912. PMID: 15872205

- Gottlieb AB. Psoriasis: emerging therapeutic strategies. Nat Rev Drug Discov. 2005 Jan;4(1):19-34. PMID: 15688070

- Bowcock AM, Cookson WO. The genetics of psoriasis, psoriatic arthritis and atopic dermatitis. Hum Mol Genet. 2004 Apr 1;13 Spec No 1:R43-55. PMID: 14996755

- Bhalerao J, Bowcock AM. The genetics of psoriasis: a complex disorder of the skin and immune system. Hum Mol Genet. 1998;7(10):1537-45. PMID: 9735374


- Cargill M, Schrodi SJ, Chang M, Garcia VE, Brandon R, Callis KP, Matsunami N, Ardlie KG, Civello D, Catanese JJ, Leong DU, Panko JM, McAllister LB, Hansen CB, Papenfuss J, Prescott SM, White TJ, Leppert MF, Krueger GG, Begovich AB. A large-scale genetic association study confirms IL12B and leads to the identification of IL23R as psoriasis-risk genes. Am J Hum Genet. 2007 Feb;80(2):273-90. PMID: 17236132