Itchy back papules with a white, flaky scale - Clinical Advisor

Itchy back papules with a white, flaky scale

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  • CA0611DermClin2

A boy aged 23 months presented with red and itchy papules on his back. The papules were 0.5 to 1.0 cm in diameter, and some were covered with a shiny, white, and flaky scale.

The lesions started one week earlier and partially spread to his torso, limbs, and scalp. Some blisters developed into vesicles that dried up without ever opening. Other symptoms included clear nasal drainage, poor sleep, and decreased appetite.

No fever, herald patches, or exposure to new foods or products were reported. The boy had a similar rash one year ago and had been diagnosed with chickenpox.



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Guttate psoriasis This patient had a special form of psoriasis known as guttate psoriasis. This relatively rare form accounts for less than 2% of all of psoriasis cases.1 Guttate psoriasis is associated with the sudden appearance of widespread 1.0- to...

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Guttate psoriasis

This patient had a special form of psoriasis known as guttate psoriasis. This relatively rare form accounts for less than 2% of all of psoriasis cases.1 Guttate psoriasis is associated with the sudden appearance of widespread 1.0- to 2.0-cm salmon-pink macules or papules. The lesions are typically concentrated on the trunk, with fewer on the face and scalp. The palms and soles are usually spared. It is not uncommon for guttate psoriasis to mimic a viral exanthem because a shower of lesions appears rather rapidly.2 Guttate psoriasis is frequently precipitated by an acute or chronic case of pharyngeal or perianal Streptococcus pyogenes infection, but it may be unrelated to streptococcal infection. Approximately two weeks after the initial eruption, the papules develop the characteristic thick, silvery scales of psoriasis.

Differential diagnoses for guttate psoriasis include viral exanthems, psoriasiform drug eruption, secondary syphilis, pityriasis rosea, lichen planus, dermatomyositis, eczema, and tinea. A detailed history and physical exam can rule out the majority of the differential list. The absence of a thick adherent scale rules out lichen planus. Additionally, lichen planus papules are purple in color and polygonal in shape. Individuals with dermatomyositis will present with muscle weakness and scaling lesions across the interphalangeal joints of the fingers. Lesions associated with pityriasis rosea differ from those of guttate psoriasis in color, shape, and distribution. Pityriasis lesions are typically dull pink or tawny, oval-shaped, and form an inverse Christmas-tree pattern over the trunk. There is also the absence of a herald patch in guttate psoriasis, which is common in pityriasis.

The diagnosis is made clinically based on lesion appearance and distribution. Presence of the Auspitz sign strongly suggests a diagnosis of psoriasis.2 Auspitz sign is the observation of pinpoint bleeding when a scale is removed. Laboratory tests that may aid in the diagnosis include an antistreptolysin O titer, a throat/perianal culture for streptococci, a KOH test to rule out candidal infections, a Tzanck smear and viral culture to rule out viral infections, and a bacterial skin culture to rule out secondary infection. When the diagnosis is in question, a biopsy can be performed to confirm. Referral to a dermatologist may be required.

Treatment may include UVB phototherapy or natural-light exposure to accelerate resolution of the lesions. Topical steroids can provide an anti-inflammatory effect and relief from itching but cannot be used chronically. For persistent lesions, treatment is the same as that for generalized plaque psoriasis. Generalized treatments for psoriasis include topical medications, intralesional steroid injections, phototherapy, and systemic therapy. Systemic therapy may include methotrexate (Rheumatrex, Trexall), cyclosporine, and acitretin (Soriatane). Appropriate antibiotic therapy for any concurrent streptococcal infection should also be administered.

The course and prognosis of guttate psoriasis occupies a wide spectrum. Sometimes this form of psoriasis resolves spontaneously within a few weeks with no treatment. Most often, one form of psoriasis will recur in the patient’s lifetime, resulting in a chronic condition that waxes and wanes throughout the life span.3 In approximately 10% of patients, psoriasis symptoms begin before age 10 years. Early onset of the disease foretells of a more serious and difficult-to-treat form of psoriasis later in life.4

At first glance, the boy’s lesions resembled varicella. A viral culture, Tzanck smear, throat culture, and varicella immunoglobulins were ordered. Physical exam was unremarkable except for the presence of Auspitz sign. The patient was prescribed diphenhydramine to treat the itching and facilitate sleep while awaiting lab results. The boy was not visibly uncomfortable during the office visit. The mother reported that he seemed to itch more when he was hot.

Lab results were consistent with a diagnosis of guttate psoriasis. Throat culture was negative. The patient’s varicella titers and immunoglobulins were low, which indicated no previous chickenpox infection. It was determined that this was an exacerbation of guttate psoriasis from one year earlier. Routine immunization for varicella was started.

The patient was started on a low-potency topical steroid cream and daily antihistamine. Because both rashes occurred in the early spring, it was thought that seasonal environmental allergens may be triggering the psoriasis outbreak. The family was provided educational material on psoriasis, and the lesions were almost completely healed at the two-week follow-up. The topical cream was discontinued after one month, and no evidence of psoriastic lesions persisted. No further exacerbations have been reported.

Ms. Waggner is a family nurse practitioner at Grand Avenue Pediatrics in Washington, Ind. The author has no relationships to disclose relating to the content of this article.


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References

1. Fitzpatrick TB, Johnson RA, Wolff K, Suurmond R, eds. Color Atlas and Synopsis of Clinical Dermatology, 4th ed. New York, N.Y.: McGraw-Hill; 2001:53.

2. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. Philadelphia, Pa: Mosby; 2004: 209-239.

3. Goodheart HP. Goodheart’s Photoguide to Common Skin Disorders: Diagnosis and Management. 3rd ed. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2009:87.

4. Krowchuk DP, Mancini AJ, eds. Pediatric Dermatology: A Quick Reference Guide. Winston-Salem, N.C.: American Academy of Pediatrics; 2006:253-257.

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