A 45-year-old man is referred for evaluation of a rash that began approximately 2 months prior to the consultation. The patient denies discomfort except for occasional itch. His medical history is positive for hypertension controlled with benazepril, which he started 18 months ago. He has no personal or family history of psoriasis or other chronic skin disorders. Physical examination reveals an extensive maculopapular dermatitis interspersed with areas of normal-appearing skin. Thickening of his palms and soles is also noted.
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Pityriasis rubra pilaris (PRP) is an uncommon papulosquamous disorder. Pityriasis connotes scaling, rubra means redness, and pilaris signifies involvement of hair follicles.1 Initial presentation may resemble seborrheic dermatitis with scaling of the scalp and patches on the forehead. Over time, patches arise on other body sites including the elbows, knees, hands, and feet. Involvement of the extremities and trunk may be extensive with characteristic “islands of sparing” (skip areas) comprised of normal-appearing skin.2 Skin on the palms and soles often thickened (referred to as palmoplantar keratoderma) and take on an erythematous to orange coloration. Painful fissures on the hands and soles may develop making walking and using one’s hands difficult. Nails can become thickened and discolored and hair may shed. Widespread disease can be accompanied by heat intolerance, protein loss, and fluid imbalance.
The majority of cases occur in adults although juvenile variants have been described. The cause of PRP is unknown. Topical therapies for patients with limited disease include corticosteroids and calcipotriol.3 Patients with more extensive disease may respond to narrowband UV-B phototherapy.4 Systemic therapies include acitretin as monotherapy5 or combined with biologics.6 Many cases of PRP spontaneously resolve after several years.
Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
1. British Association of Dermatologists. Pityriasis rubra pilaris leaflet. BAD website. Udated September 2019. Accessed May 8, 2023. http://www.bad.org.uk/shared/get-file.ashx?id=116&itemtype=document
2. Ngan V, Oakley A. Pityriasis rubra pilaris. DermNet. Updated October 2015. Accessed May 8, 2023. https://dermnetnz.org/topics/pityriasis-rubra-pilaris
3. Van de Kerkhof PC, Steijlen PM. Topical treatment of pityriasis rubra pilaris with calcipotriol. Br J Dermatol. 1994;130(5):675-678. doi:10.1111/j.1365-2133.1994.tb13121.x.
4. Vergilis-Kalner IJ, Mann DJ, Wasserman J, Petronic-Rosic V, Toukas, MM. Pityriasis rubra pilaris sensitive to narrow band-ultraviolet B light therapy. J Drugs Dermatol. 2009;8(3):270-273.
5. Atzori L, Zanniello R, Lappi A, et al. Successful treatment of erythrodermic pityriasis rubra pilaris with acitretin. Dermatol Ther. 2018;31(5):e12694. doi:10.1111/dth.12694
6. Chastagner M, Hoelt P, Kanitakis J, Jullien D, Villani AP. Successful treatment of TNFα inhibitor-resistant pityriasis rubra pilaris with ixekizumab and acitretin. Eur J Dermatol. 2019;29(2):218-220. doi:10.1684/ejd.2019.3502