Treatment of prurigo with methotrexate: a multicentre retrospective study of 39 cases.

Background: Prurigo is a common primary pruritic condition. Treatment is challenging. Methotrexate (MTX) is effective for the treatment of pruriginous dermatoses, but its use in prurigo has been little studied.

Objectives: To investigate the efficacy and safety of MTX in the treatment of difficult-to-treat prurigo.

Methods: Patients from six university dermatology departments treated with MTX between 2006 and 2016 for difficult-to-treat prurigo (i.e. with failure to conventional therapies) were included in this retrospective multicentre study. Patients with other pruritic dermatoses were excluded. Clinical efficacy was recorded after 3, 6 and 12 months of treatment: (i) subjective efficacy, that is, evaluation of the pruritus by the patient and (ii) objective efficacy, that is, assessment of cutaneous lesions by the physician: complete or almost complete remission (CR) (healing of lesions), partial remission (PR) (incomplete improvement of lesions) or failure (no improvement or worsening). The overall response rate (ORR) included CR and PR.

Results: Thirty-nine patients with previous failure of topical steroids, H1-antihistamine drugs or phototherapy were included. The median weekly dose of MTX was 15 mg (range 5-25 mg). The median follow-up was 16 months (2-108). The mean time between onset of MTX and objective efficacy was 2.4 ± 1.2 months and the mean duration of response was 19 ± 15 months. The ORR was 91% at 3 months [n = 36, CI 95% (81.2-100.8%), CR 44%], 94% at 6 months [n = 32, CI 95% (85.7-102.2%), CR 56%] and 89% at 12 months [n = 28, CI 95% (77.4-100.6%), CR 57%]. Seven patients stopped MTX because of failure, and five because of the discovery of hepatocarcinoma (n = 1), elevated transaminases (n = 1), infectious pneumonitis (n = 1) or gastrointestinal symptoms (n = 2).

Conclusion: Methotrexate is a therapeutic option in difficult-to-treat prurigo.