Guttate Psoriasis

Guttate psoriasis is a distinctive acute skin eruption characterised by small drop-like 1-10 mm diameter salmon-pink papules which usually have a fine scale. This variant primarily occurs on the trunk and the proximal extremities, but it may have a more generalised distribution. A history of an upper respiratory infection secondary to group A beta-haemolytic streptococci often precedes the eruption by 2-3 weeks. Guttate psoriasis may be chronic and unrelated to streptococcal infection.

• More common in individuals younger than 40 years but uncommon in those under 10 years.
• Genetic predisposition: guttate psoriasis has been linked with HLA-BW17, HLA-B13, HLA-CW6.
• Often associated with streptococcal infection but may also be associated with stress, trauma (Koebner phenomenon) or drugs, e.g. antimalarials, non-steroidal anti-inflammatories, beta blockers.

• In most cases there is an history of an antecedent streptococcal infection, usually of the upper respiratory tract, such as pharyngitis or tonsillitis, 2-3 weeks prior to the eruption.
• There may be a positive family history of psoriasis.
• The onset of the skin lesions is often acute, with multiple papules erupting on the trunk and the proximal extremities.
• Lesions may sometimes spread to involve the face, ears and the scalp.
• The palms and the soles are rarely affected.
• The rash is often associated with mild itching.
• Like other forms of psoriasis, guttate psoriasis tends to improve during the summer and worsen during the winter.
• Examination of the skin reveals characteristic lesions consisting of multiple, discrete drop-like salmon-pink papules. A fine scale may be seen on established lesions.
  
  
  
  
  
  
• Nail changes characteristic of chronic psoriasis, e.g. pits, ridges, and the oil-drop sign, are usually absent.

• Nummular dermatitis
• Pityriasis rosea
• Lichen planus
• Drug eruption
• Viral exanthem
• Syphilis
• Cutaneous T-Cell lymphoma
• Pityriasis lichenoides

• Diagnosis is clinical and biopsy is usually not required.
• Serology: levels of antibodies to streptolysin O, hyaluronidase, and deoxyribonuclease B may be elevated in more than one half of patients.
• Cultures: bacterial culture of the throat or perianal area may be helpful to isolate the organism in selected cases.

• Usually resolves within a few weeks without treatment. Simple reassurance and emollients may therefore be sufficient.
• There is no firm evidence on specific treatment for acute guttate psoriasis.¹
• Antimicrobials: because of the clear association between guttate psoriasis and streptococcal infection in most cases, antibiotic treatment is often given but there is no evidence of any definite benefit.² A recent study found there was no significant improvement in streptococcus associated guttate psoriasis with or without a course of oral penicillin or erythromycin.³
• Phototherapy: clearance of guttate lesions can be accelerated by judicious exposure to sunlight or by a short course of narrow band UV-B phototherapy.
• Although unproven by large controlled clinical trials, tonsillectomy for patients with recurrent or chronic guttate psoriasis associated with post-streptococcal tonsillitis may be helpful but there is no evidence of any benefit.²

• Areas of the skin that have been treated with high-potency topical steroids for long periods may show some atrophy, telangiectases, and hypopigmentation.
• Patients on PUVA may experience a number of adverse effects, such as nausea and vomiting.
• The psoralen-induced photosensitivity persists up to 24 hours after administration of the drug. Patients should be adequately informed about the need to wear protective lenses and to avoid sun exposure during this period.

• Guttate psoriasis often runs a self-limited course over several weeks to a few months but develops into chronic plaque-type psoriasis in approximately two-thirds of cases.
• Scarring is not a problem.
• Previously affected areas may show post-inflammatory hypopigmentation or hyperpigmentation.
• Recurrent episodes may occur, especially with pharyngeal carriage of streptococci.