psoriasis

PO

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.

Variants

ICD-10:
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

Images

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

• https://twitter.com/DermpathMGH/status/755802030610976768

 cutaneous psoriasis

• https://twitter.com/STEVENKOLKERMD/status/1589289634697449472

Synopsis

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

• neutrophil exocytosis
• Munro microabscesses

 psoriasis

• regular acanthosis with club shaped rete ridges
• confluent parakeratosis
• hypogranulosis
• intracorneal neutrophils
• acanthosis
• vascular congestion of papillary dermis

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

Variants

 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)

Reviews

 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

References

 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