Linear psoriasis (LP) is a rare form of psoriasis with 2 distinct profiles — isolated LP and superimposed LP — and is more resistant to treatment than classic psoriasis, according to the results of a retrospective study conducted at 14 French medical centers and published in the American Journal of Clinical Dermatology.
The investigators sought to better understand LP in a large-scale study. Medical records were retrospectively reviewed between February 1 and July 31, 2015. Patients newly diagnosed with LP, with or without supporting histology, were included in the analysis. The clinical features, treatments, and efficacy of various therapies were evaluated for each patient.
A total of 30 cases of LP were reported in the analysis. Mean patient age was 26.8 years; there were 13 men and 17 women included in the cohort. The mean age at LP onset was 20.0 years, with LP developing in 18 of the 30 patients during childhood. Of note, age at LP diagnosis appears to be younger than age at diagnosis of classical psoriasis. Of the 30 patients with LP who were evaluated, 10 had a family history of psoriasis and 2 had psoriatic arthritis.
Overall, 19 cases of psoriasis were considered linear at onset, with concomitant classic psoriasis; these cases were defined as superimposed LP. The other 11 cases, which were not associated with classic psoriasis, were termed isolated LP.
In 4 of the 19 cases of superimposed LP, the disorder developed while the patient was being treated with methotrexate (n=2), etanercept (n=1), or infliximab (n=1). The use of topical corticosteroids was effective in 76% of cases, and systemic therapies were effective in <66% of cases. Treatments were shown to be less effective in patients with LP than in those with classic psoriasis.
The investigators concluded that studies using molecular analysis to compare DNA samples from LP and non-LP skin areas of patients might help clarify the molecular basis of the psoriasis disease process and thus improve treatment efficacy.
Say M, Boralévi F, Lenormand C, et al; Groupe de Recherche sur le Psoriasis de la Société Française de Dermatologie, and the Groupe de Recherche de la Société Française de Dermatologie Pédiatrique. Clinical and therapeutic aspects of linear psoriasis: a study of 30 cases [published online March 29, 2018]. Am J Clin Dermatol. doi: 10.1007/s40257-018-0354-9