Guttate psoriasis in Adult
Current evidence supports the theory that plaque psoriasis and guttate psoriasis are similar in that an environmental factor triggers an immune reaction in a genetically susceptible individual. The environmental factor in the case of guttate psoriasis is often a streptococcal infection, and a T-cell driven immune reaction is elicited, leading to increased type 1 helper T-cells (Th1) activity and increased interferon gamma (IFN-g) and interleukin-2 (IL-2) cytokine levels. Regarding a genetically susceptible host, it has been demonstrated that HLA-Cw*0602-positive patients are more likely to develop guttate psoriasis.
Guttate psoriasis occurs in all races, both sexes, and is most commonly seen in children and young adults younger than 30. The clinical course is unpredictable. In children, spontaneous remission over weeks to months is common, while in young adults, it may represent the first stage in the development of chronic plaque psoriasis.
While streptococcal infection is the most common trigger of guttate psoriasis, other infections, such as varicella and Pityrosporum ovale, and drugs, such as TNF-alpha inhibitors, have also been implicated.
Immunocompromised Patient Considerations:
The prevalence of psoriasis in patients with HIV is approximately 5%, and it is associated with a more severe clinical course. Psoriasis may pre-exist in the patient with HIV or manifest as a progression of the virus.
L40.4 – Guttate psoriasis
37042000 – Guttate psoriasis
Differential Diagnosis & Pitfalls
- Nummular dermatitis – Intensely pruritic, coin-shaped lesions almost exclusively seen on the extremities.
- Tinea corporis – Usually fewer isolated lesions. Check potassium hydroxide (KOH) prep.
- Tinea versicolor – Less scale and less inflammatory. KOH-positive.
- Pityriasis rosea – Look for a herald patch, collarette of scale, and orientation of lesions (fir-tree pattern in skin tension lines).
- Small plaque parapsoriasis – More common in older adults; chronic asymptomatic patches.
- Pityriasis lichenoides chronica – Biopsy will assist in differentiating from guttate psoriasis, predominantly CD8+ T-cell infiltrate.
- Secondary syphilis – Check rapid plasma reagin (RPR) if this is suspected; assess for history of primary chancre and systemic symptoms.
- Lymphomatoid papulosis – Biopsy will assist in differentiating from guttate psoriasis, predominantly CD30+ T-cell infiltrate. Generally presents as recurrent crops of papules.
- Psoriasiform drug eruption – Ask about medication history.
- Viral exanthem – Usually less scaly.
- Chronic papular atopic dermatitis