An 8-year-old girl presents with a scaly salmon-colored pruritic rash covering her entire body. The rash first appeared a few weeks earlier when the child appeared dehydrated and her mother noticed that her face looked dry. Within a few days the girl’s skin began flaking and the rash spread from her face to her scalp. The girl was initially diagnosed with eczema and treated with a corticosteroid shampoo (Fluocinolone acetonide 0.01%), which provided only temporary relief. Within two weeks a red raised patchy rash had spread to the patient’s torso, back, arms, legs and hands. The skin on the child’s palms and soles appeared thick, cracked and orange-hued. Medical history was unremarkable except for a case of streptococcal pharyngitis two months earlier. What’s your diagnosis?Submit your answer, and then read the full explanation below. If you like this activity or have a suggestion, tell us about it in the comment box at the bottom of the page.
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Pityriasis rubra pilaris is a chronic papulosquamous disorder of unknown etiology characterized by reddish-orange scaly plaques that can progress to erythroderma. Most cases are sporadic, but a familial form of the disease with an autosomal dominant inheritance pattern has been observed. Disease incidence in the United States is about one case per 3,500-5,000 patients who present to dermatology clinics.
Although no one knows what causes pityriasis rubra pilaris, researchers have hypothesized that the disorder is an immune reaction to an antigen trigger. Several case reports have linked the disorder to prior streptococcal infection and the disease has been reported in patients with HIV.
Griffiths classification system divides the disorder into five distinct categories: classic adult type I, atypical adult type II, classic juvenile type III, circumscribed juvenile type IV, atypical juvenile type V and HIV-associated type VI.
Although there are no specific laboratory tests available to confirm pityriasis rubra pilaris, clinicians should perform a biopsy and histological tests to rule out other possible papulosquamous and erythrodermic disorders.
Characteristic features on light microscopy include hyperkeratosis with alternating orthokeratosis and parakeratosis in a checkerboard pattern.
The presence of acantholysis, hypergranulosis, follicular plugging, and the absence of dilated capillaries and epidermal pustulation may help clinicians distinguish pityriasis rubra pilaris from psoriasis.
Because pityriasis rubra pilaris is such a rare disorder, no long-term data are available to confirm treatment efficacy, but anecdotal reports suggest that several options may be useful for alleviating symptoms, reducing morbidity and preventing complications.
Clinicians may consider topical medications including corticosteroids, retinoids and emollients to relieve dryness and fissuring and provide patient comfort. Phototherapy is an option for nonresponsive patients.
Oral retinoids including acetretin and isotretinoin improved symptoms in 80% of 12 patients treated with the medication within four to six months.
Benefits have also been reported with the antimetabolites azathioprine and methotrexate; monoclonal antibodies including etanercept, infliximab and adilimumab; and the immunosuppressant cyclosporine.
Patients should be monitored for electrolyte abnormalities, hypoalbuminia, secondary bacterial skin infection and sepsis, due to risk for liver disease/failure and cancer.
Prognosis varies depending on the form of the disease; however, familial pityriasis rubra pilaris generally persists throughout life whereas patients who have acquired the disease may experience remissions and exacerbations. Some patients experience spontaneous resolution within one to three years.
2. Goldsmith LA, Baden HP. Pityriasis rubra pilaris. In Freedberg IM, Isin AZ, Wolff K, et al. Fitzpatrick’s Dermatology in General Medicine. 5th ed. New York: McGraw-Hill; 1999: 538-540.
3. Mohrenschlager M, Abeck D. Pediatr Dermatol. 2002;19:569.