Rash on boy’s trunk and extremities after upper respiratory infection
Parents of a 6-year-old boy bring him to your office for urgent consultation for a rash that blossomed on his trunk and extremities 2 weeks ago following an upper respiratory infection and that shows no sign of improving. What’s the diagnosis?
The Case
Parents of a 6-year-old boy bring him to your office for urgent consultation for a rash that blossomed on his trunk and extremities 2 weeks ago following an upper respiratory infection and that shows no sign of improving.
NEXT: What’s the diagnosis?
Clinical findings and epidemiology
Psoriasis is a common skin disorder affecting 2% to 4% of the US population.1 It is characterized by the development of well-demarcated red plaques with silvery scale, variable itching, and with a predilection for the extensor surfaces of the arms and legs, scalp, and areas prone to trauma.1 Numerous variants of this disease include chronic plaque, guttate, inverse, erythrodermic, pustular, and nail psoriasis.1,2
Next: A 12-year-old with a perplexing rash
Acute guttate psoriasis (AGP) is most commonly seen in children and young adults aged younger than 30 years.3,4 Our patient was typical, presenting with the acute onset of numerous, small (2–15 mm), dew-drop-like, salmon pink papules and plaques with fine scale on the trunk and proximal extremities.3 Lesions may also occur on the scalp, hands, feet, and nails, but interestingly, the elbows and knees-the traditional sites of chronic psoriatic involvement-are rarely affected.3 Acute guttate psoriasis is strongly associated with streptococcal infection. In some series, as many as 80% of patients with guttate psoriasis have clinical or laboratory evidence of past or present streptococcal infection.4,5 Viral upper respiratory infections, urinary tract infections, and other acute infections have also been reported to trigger outbreaks.1,3–5 There is also a strong association between guttate psoriasis and a family history of psoriasis, with these patients more likely to progress into chronic plaque-type psoriasis later in life.3,4
Differential diagnosis
Guttate psoriasis has a fairly unique appearance, but it may be confused with other papulosquamous eruptions such as pityriasis rosea, tinea corporis, secondary syphilis, pityriasis lichenoides chronica, and nummular dermatitis. A careful history and physical exam can usually clinch the diagnosis, but occasionally a biopsy must be performed.
Course and treatment
Although the majority of patients with guttate psoriasis experience complete remission over the course of several months, others may have intermittent recurrences or even progression to chronic plaque psoriasis.3 During the spring and summer, lesions may regress with judicious sun exposure. Given that the eruption often spontaneously resolves, patients may choose to forego therapy, although most pursue treatment. The regimen for guttate psoriasis overlaps with that of chronic plaque psoriasis and includes phototherapy (narrowband ultraviolet light B [UVB] or psoralen and UVA light) and topical agents (corticosteroids plus vitamin D analogs).1,2 Because of the strong association of AGP with Streptococcus pyogenes, it has been suggested that even those without infectious symptoms should be assessed for evidence of streptococcal infection.2 This is controversial, as the benefit of antibacterial therapy in guttate psoriasis is largely unproven.
In summary, AGP is a variant of psoriasis that presents with small, drop-like, erythematous papules and plaques with a fine scale. It is most frequently diagnosed in adolescents and young adults and often follows infection with S pyogenes. Although it may spontaneously remit, treatment options include phototherapy and topical corticosteroids.
Outcome
Our patient responded quickly to topical steroids and sun exposure, with clearing achieved over 3 weeks.
References
1. Silverberg NB. Update on pediatric psoriasis. Cutis. 2015;95(3):147-152.
2. Shah KN. Diagnosis and treatment of pediatric psoriasis: current and future. Am J Clin Dermatol. 2013;14(3):195-213.
3. Ko HC, Jwa SW, Song M, et al. Clinical course of guttate psoriasis: long-term follow-up study. J Dermatol. 2010;37(10):894-899.
4. Naldi L, Peli L, Parazzini F, Carrel CF; Psoriasis Study Group of the Italian Group for Epidemiological Research in Dermatology. Family history of psoriasis, stressful life events, and recent infectious disease are risk factors for a first episode of acute guttate psoriasis: results of a case-control study. J Am Acad Dermatol. 2001;44(3):433-438.
5. Telfer NR, Chalmers RJ, Whale K, Colman G. The role of streptococcal infection in the initiation of guttate psoriasis. Arch Dermatol. 1992;128(1):39-42.
Ms Klein is a fourth-year medical student at Penn State Hershey College of Medicine, Hershey, Pennsylvania. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
