Guttate psoriasis occurs mainly in childhood or young adulthood. It appears as a shower of small rashes, more or less generally all over the body, following an acute streptococcal infection.
Guttate psoriasis is much more common in individuals with a family history of the common plaque type of psoriasis, the psoriasis vulgaris. It is the least severe amongst the psoriasis clinical types.
Guttate Psoriasis Causes
A variety of conditions have been known to bring on an attack of guttate psoriasis, including upper respiratory infections, streptococcal infections, tonsillitis, stress, injury to the skin and the administration of certain drugs including antimalarials, lithium and beta-blockers.
The majority of guttate psoriasis cases in childhood follow streptococcal throat infections.
Guttate lesions may also occur in patients with chronic plaque psoriasis when they are exacerbated, called the unstable psoriasis.
How Does Infection Cause Guttate Psoriasis?
It has been postulated that an immunological mimicry between antibodies against bacterial super antigens and keratin proteins in the skin leads to activation of auto reactive T lymphocytes, which are responsible for the changes taking place in psoriatic skin. This occurs in genetically predisposed individuals. Both guttate and plaque psoriasis share strong gene associations with a specific gene called PSOR1, which resides in the short arm of chromosome 6.
Guttate Psoriasis Clinical Features
Following the inducing event, pin head to pea sized, tiny rain drops-like (guttate), erythematous (red) rashes erupt abruptly. The distribution is bilaterally symmetrical all over the body, especially the trunk, sparing the palms and soles. Sometimes face, ears and scalp may also be affected in guttate psoriasis, but this is infrequent. Scales are not evident in the early stage. Compared to plaque psoriasis, the scales that form in guttate psoriasis are thin.
Although the guttate lesions are normally profuse, in many cases there are no more than one dozen present on the body.
The rashes are 2 to 3 mm to 1 cm in diameter, usually round or oval in shape.
Guttate Psoriasis Diagnosis
Clinical diagnosis is mainly by the morphology of the scales, the distribution and a history of triggering event, usually a streptococcal throat infection preceding the appearance of the rashes. Antistreptolysin O(ASO) titer is usually high. Biopsy from a skin rash shows the typical histopathological changes of psoriasis.
Guttate Psoriasis Differential Diagnosis
Secondary syphilis, pityriasis rosea and drug eruptions may show similar rashes and have to be ruled out in a case of suspected guttate psoriasis.
Guttate Psoriasis Treatment
Persons who have a history of psoriasis should treat any strep throat infections immediately to prevent outbreak of guttate psoriasis. As most cases of guttate psoriasis are self limiting, active measures are not required in managing the disease.
Application of bland emollients like moisturizing lotion at night and Vaseline cream in the morning will usually control the rashes and enhance healing. Avoidance of other psoriasis triggers like alcohol and smoking will help.
Guttate Psoriasis Prognosis
Guttate psoriasis may resolve on its own, occasionally leaving aperson free of further outbreaks, or it may clear for a time only toreappear later as patches of plaque psoriasis.
Prognosis is usually good; lesions resolve in a few weeks without leaving many marks.
Next: Plaque Psoriasis or Psoriasis Vulgaris
Reference:
Psoriasis, in Rook’s Textbook of Dermatology, 7th Edition, 2004
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