S1902 The Association Between Lichen Planus and Inflammatory Bowel Disease: A Multicenter Population-Based Study

Introduction: Both lichen planus (LP) and inflammatory bowel disease (IBD) exhibit T cell-dominant immunopathology and are associated with autoimmune comorbidities. Despite conceptual links in immunological literature, original research examining associations between LP and IBD remains limited. This study assessed associations between IBD and lichen planus. Methods: We accessed data through a large-scale health research network from 102 healthcare organizations across the United States, representing >150 million patients (TriNetX, Cambridge, MA; exempt from IRB review; data accessed April 28, 2025). We identified adult patients (≥18 years) with ≥2 instances of Crohn's disease (CD; International Classification of Diseases-10: K50) or ulcerative colitis (UC; International Classification of Diseases-10: K51). We excluded patients with one index diagnosis, both CD and UC diagnoses, and those with psoriasis (International Classification of Diseases-10: L40) or atopic dermatitis (International Classification of Diseases-10: L20). We collected patient demographics, medications, comorbidities, and lichen planus diagnoses (International Classification of Diseases-10: L43). Results: We identified 160,343 CD patients and 146,970 UC patients. LP prevalence was 0.3% (n = 446) in CD and 0.4% (n = 546) in UC. LP diagnosis followed IBD diagnosis in 66.4% of CD and 63.4% of UC cases. IBD patients with LP were significantly older with female predominance. UC patients with LP showed high rates in the 70-80 age group (30.8% vs 11.8%). Higher viral infection prevalence was observed in IBD-LP patients, including COVID-19 (6.8% vs 2.3% in UC, P < 0.001; 6.7% vs 1.5% in CD, P < 0.001) and herpes zoster (6.6% vs 1.2% in UC, P < 0.001; 5.6% vs 0.8% in CD, P < 0.001). Hepatitis C was significantly more prevalent in IBD-LP patients. Known LP-triggering medications (nonsteroidal anti-inflammatory drugs, beta blockers, thiazides, ACE inhibitors) were more prevalent in IBD-LP patients. Conclusion: This analysis reveals significant associations between IBD and lichen planus with clinical implications. Results emphasize need for dermatologic surveillance in IBD patients, especially those receiving LP-triggering medications or with viral infections. Medication review should be standard for IBD patients developing LP. Older age and female predominance patterns may guide screening strategies, establishing IBD patients as high-risk for LP development.