Rapid-onset rash
A 7-year-old boy was brought to his family physician for evaluation of a mildly pruritic spreading rash. Ten days earlier, the skin eruption had appeared, and he was given a diagnosis of streptococcal pharyngitis, which was confirmed by a throat swab and positive antistreptolysin O titer. Physical examination revealed multiple erythematous, scaly papules and plaques on the patient’s trunk, arms, and legs. His palms and soles were spared.
What is your diagnosis?
A diagnosis of guttate psoriasis was made based on the physical exam findings and the preceding group A beta-hemolytic streptococcal infection.
This condition affects approximately 2% of all patients with psoriasis; it is characterized by the acute onset of multiple erythematous and scaly papules and small plaques that look like droplets (“gutta”). It tends to affect children and young adults and typically occurs following an acute infection (eg, streptococcal pharyngitis). In this case, a rapid strep test was positive for group A Streptococcus, which supported the diagnosis.
,The differential includes skin conditions such as pityriasis rosea, tinea corporis, and contact dermatitis.
The first-line treatment for streptococcal infection is amoxicillin (50 mg/kg/d [maximum: 1000 mg/d] orally for 10 d) or penicillin G benzathine (for children < 60 lb, 6 × 105 units intramuscularly; children ≥ 60 lb, 1.2 × 106 units intramuscularly). For the psoriasis lesions, treatment options include topical steroids, vitamin D derivatives, or combinations of both. In most cases, guttate psoriasis completely resolves. However, one-third of children with guttate psoriasis go on to develop plaque psoriasis later in life.
This patient was treated with penicillin G benzathine (1.2 × 106 units intramuscularly) and a calcipotriol/betamethasone combination gel. However, a less costly treatment is generic betamethasone (or triamcinolone) and/or generic calcipotriol (a vitamin D derivative). The streptococcal infection and skin lesions completely resolved. No adverse events were reported, and no relapse was observed after 3 months.
This case was adapted from: Matos RS, Torres T. Rapid onset rash in child. J Fam Pract. 2018;67:E1-E2.