Pityriasis rubra pilarisFrom the Ronald O. Perlman Department of Dermatology, New York University
Katherine L White MD
Dermatology Online Journal 9(4): 6
Pityriasis rubra pilaris is a chronic, papulosquamous dermatosis of unclear etiology. The case of a 61-year-old man with pityriasis rubra pilaris is presented. The clinical forms, histopathologic features, and treatment options of pityriasis rubra pilaris are reviewed.
History.—A 61-year-old man presented to the Charles C. Harris Skin and Cancer Pavilion in August 2001 for evaluation and management of a diffuse, erythematous, scaly eruption of 5 months' duration. He had been treated with oral glucocorticoids and isotretinoin (0.5 mg/kg/day) as well as with emollients. These treatments produced only temporary clearance. The patient reported four episodes of total body involvement resulting in exfoliative erythroderma. A biopsy specimen obtained elsewhere provided a diagnosis. Recent biopsy specimens were confirmatory. The patient reported intense pruritus and joint pains of the knees and proximal interphalangeal joints of the hands. Acitretin (1 mg/kg/day) and a trial of tacrolimus (0.1 %) ointment twice daily were initiated as therapy.
Past medical history includes a hernia repair and laparotomy for a small bowel obstruction 30 years ago. He rarely takes zolpidem for insomnia and alprazolam for anxiety. There was no family history of a similar eruption.
Physical examination.—Numerous, 0.5-2-cm, erythematous patches with fine scale and subtle follicular prominance were present over the neck, torso, and upper and lower extremities. The hands showed hyperkeratosis and fissures. The feet showed hyperkeratotic plaques of the soles in a sandal-like distribution, with onychodystrophy and subungual hyperkeratosis that was most marked on the great toes.
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Laboratory data.—A complete blood count showed a white-cell count of 3.9 x 109/L, with 42 percent neutrophils, 43 percent lymphocytes, 14 percent monocytes, and 2 percent eosinophils. Hemoglobin and hematocrit levels and a platelet count were normal. A KOH examination from the scaly plantar plaques was negative for fungal hyphae. A human-immunodeficiency-virus test, rapid plasma reagin test, anti-nuclear antibody titer, and a Lyme antibody test were negative. A metabolic profile was normal except for an elevated glucose of 116 mg/dL.
Histopathology.—There is psoriasiform hyperplasia of the epidermis with alternating areas of orthokeratosis and parakeratosis and plugs of the follicular infundibulum. A sparse, superficial, perivascular lymphocytic infiltrate is also noted.
Diagnosis.—Pityriasis rubra pilaris.
Pityriasis rubra pilaris is a chronic, papulosquamous skin disease of unknown etiology, classically characterized by small follicular papules, scaly yellow-pink (salmon-colored) patches, and palmoplantar hyperkeratosis. Lesions are usually symmetrical and diffuse, with areas of normal skin (islands of sparing). Progression to erythroderma is common. In 1980, Griffiths  classified pityriasis rubra pilaris into five types based on age and pattern of onset as well as prognosis. Type I is classic adult type pityriasis rubra pilaris; type II is atypical adult pityriasis rubra pilaris; type III is classic juvenile pityriasis rubra pilaris; type IV is circumscribed juvenile pityriasis rubra pilaris; and type V is atypical juvenile pityriasis rubra pilaris. The classic adult type, which accounts for 50 percent of cases, has the best prognosis, with 80 percent clearing by 3 years. The 10 percent of patients with atypical adult-type have a more chronic course, with 20 percent remission by three years. The juvenile types share a poorer prognosis for remission. The incidence is bimodal, with peaks in the first and fifth decades. The etiology is unclear, but some juvenile cases may be inherited in an autosomal dominant pattern. More recently, a type VI pityriasis rubra pilaris, or human-immunodeficiency-virus-associated pityriasis rubra pilaris, has been described. It appears to have a variable association with acne conglobata, hidradentitis suppurativa, and lichen spinulosus. 
Clayton et al.  have emphasized the importance of clinical and histopathological correlation in establishing the diagnosis of pityriasis rubra pilaris. In this case, less typical physical findings correlate with classic histopathologic features. Biopsy specimens from this patient showed follicular plugs, hyperkeratosis with alternating ortho- and parakeratosis, and a superficial perivascular lymphocytic infiltrate.
Oral retinoids are the mainstay of treatment of adult pityriasis rubra pilaris. Dicken reviewed the clinical response to different therapies of seventy-five patients with adult-type pityriasis rubra pilaris. Of the fifteen patients treated with isotretinoin, ten had complete resolution and two had partial resolution. Oral retinoids can be combined with methotrexate. In a 10-year case series, Clayton et al. documented 25-75 percent improvement in 17 of 24 patients with adult-type pityriasis rubra pilaris treated for 16 weeks with oral retinoids and concurrent or later low-dose weekly methotrexate.  Other treatments, such as Goekerman therapy, glucocorticoids, high-dose vitamin A with or without concomitant vitamin E, azathioprine, and phototherapy, have not shown consistent clinical efficacy. Controversy about the role of cyclosporine in the treatment of pityriasis rubra pilaris exists. While most studies show lack of efficacy, a report of 3 cases of adult-type pityriasis rubra pilaris responsive to cyclosporine at a dose of 5 mg/kg was recently published. Human-immunodeficiency-virus-associated pityriasis rubra pilaris has responded to triple anti-retroviral therapy.  For symptomatic relief, emollients, keratolytics, and antihistamine therapy are beneficial.
References1. Griffiths WAD. Pityriasis rubra pilaris. Clin Exp Dermatol 1980;5:105.
2. Gonzalez-Lopez A, et al. HIV-associated pityriasis rubra pilaris responsive to triple antiretroviral therapy. Br J Dermatol 1999;140:931.
3. Clayton BD, et al. Adult pityriasis rubra pilaris: a 10-year case series. J Am Acad Dermatol 1997;36:959.
4. Dicken CH. Treatment of classical pityriasis rubra pilaris. J Am Acad Dermatol 1994;31:997.
5. Kazunari U, et al. Three cases of pityriasis rubra pilaris successfully treated with cyclosporin A. Dermatology 2000;200:324.
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