New Onset Guttate Psoriasis Following Pandemic H1N1 Influenza Vaccination
A 26-year-old Korean female was presented with guttate psoriasis-like lesions of multiple erythematous scaly macules scattered on her extremities and trunk (). She was injected with an inactivated split-virus influenza A/H1N1 vaccine without adjuvant (Greenflu-S®) on her left deltoid area ten days before the visit to our department. The first lesion appeared on the injection site three days after the vaccination, and its size slowly increased (). After a few days, multiple small scaly macules developed on the trunk and extremities. On the lesion on her back, an Auspitz sign was observed when silvery scales were removed. She suffered appendicitis four months before the vaccination and had no history of any other inflammatory disorders. There was no personal or family history of psoriasis. Routine laboratory investigation results were within the normal range of limits except for antistreptolysin-O (ASO) titer, which elevated to 773 IU/ml (normal: <200 IU/ml). However, there was no definite history of streptococcal infection, such as pharyngitis. Histopathological examination showed neutrophilic collections within the parakeratotic cornified layer, moderate acanthosis, diminished granular layer, elongation and edema of the dermal papillae, and dilated capillaries (). The lesions were successfully treated with topical steroids and ultraviolet B phototherapy within three weeks. And for the following fourteen months, there was no relapse.