Complete Remission of Severe Chronic Plaque Psoriasis Following Isoniazid Therapy for Latent Tuberculosis: A Novel Clinical Observation and Case Report

Background: Latent tuberculosis infection (LTBI) screening is extremely crucial to initiate biological therapy among psoriasis patients as they potentially face TB activation. The lack of equal distribution of LTBI dwells on regional differences evoking a customized management. This report describes a unique case of psoriasis remission post-LTBI treatment and discusses its mechanistic implication. Case Presentation: The patient is a 48-year-old man with an indication of severe chronic plaque psoriasis (PASI 36.9) that was positive on interferon-gamma release assay test (IGRA) but showed no active signs of TB on chest x-ray. He was put on isoniazid (300 mg/day, 6 months) and pyridoxine. Results: After three months, there was a marked resolution to the psoriatic lesions which were fully cleared after six months. There was remission throughout 6 months of follow-up. Conclusion: Possible immunomodulatory effect of isoniazid in psoriasis resolution after treating LTBI can be explained by potential inhibition of Th1/Th17 pathways. This case supports the necessity of additional studies of the association between LTBI and the pathogenesis of psoriasis.