Is there an association between lichen planus (LP) and interstitial nephritis in patients with a history of autoimmune or inflammatory conditions?

Association Between Lichen Planus and Interstitial Nephritis

There is no established direct association between lichen planus (LP) and interstitial nephritis in the medical literature. However, interstitial nephritis has been documented as an extra-intestinal manifestation of inflammatory bowel disease (IBD), and both LP and interstitial nephritis can occur as separate autoimmune phenomena in patients with underlying autoimmune conditions.

Key Evidence on Lichen Planus and Renal Disease

Direct Association Evidence

• No documented link exists between lichen planus and interstitial nephritis in the available guideline and research literature 1, 2, 3.
• Lichen planus is recognized as a T-cell mediated autoimmune disease affecting skin and mucous membranes, but renal involvement is not described as part of its clinical spectrum 4, 2, 3.

Interstitial Nephritis in Autoimmune Contexts

• Tubulo-interstitial nephritis, including granulomatous interstitial nephritis, has been reported as an extra-intestinal manifestation of inflammatory bowel disease (IBD), not lichen planus 1.
• Several cases of glomerulonephritis associated with IBD have been documented, suggesting potential autoimmune kidney involvement in inflammatory conditions 1.

Drug-Induced Interstitial Nephritis Risk

• The most important clinical consideration is drug-induced interstitial nephritis from medications used to treat autoimmune conditions 1.
• Sulfasalazine and 5-ASA can cause interstitial nephritis (either acute or chronic), independently of dose administered, with injury that is reversible except when diagnosis is delayed 1.
• Immune checkpoint inhibitors can cause interstitial nephritis in 2-5% of patients, typically occurring 3-10 months after treatment initiation 1.
• Ciclosporin can cause chronic renal impairment including interstitial fibrosis and tubular nephropathy in up to 20% of patients 1.

Autoimmune Disease Associations with Lichen Planus

Documented Autoimmune Comorbidities

• Lichen planus is significantly associated with systemic lupus erythematosus (OR: 2.87), Sjögren's syndrome (OR: 3.75), dermatomyositis (OR: 6.34), vitiligo (OR: 2.09), and alopecia areata (OR: 2.82) in a nationwide case-control study 5.
• These associations suggest LP occurs in the context of broader autoimmune dysregulation, but renal disease is not among the documented associations 5.

Conflicting Evidence on Autoimmune Background

• One older study found no increase in autoimmune disease incidence or autoantibody frequency in LP patients compared to controls 6.
• More recent evidence demonstrates LP is a classical cell-mediated autoimmune disease with other autoimmune diseases often associated 3, 5.

Clinical Approach When Both Conditions Coexist

Diagnostic Evaluation

• If a patient with lichen planus develops renal impairment, prioritize excluding drug-induced causes first by reviewing all medications including topical corticosteroids, systemic immunosuppressants, and any IBD-related medications 1.
• Monitor serum creatinine at baseline and at intervals throughout immunosuppressive treatment, with weekly monitoring for grade 1 elevations and every 2-3 days for grade 2 elevations 1.
• Perform renal biopsy if creatinine remains elevated >2-3 days after excluding dehydration and nephrotoxic medications to distinguish between drug-induced, autoimmune, or coincidental causes 1.

Common Pitfalls to Avoid

• Do not assume a causal relationship between LP and interstitial nephritis without excluding medication effects, as this is the most common reversible cause 1.
• Do not overlook screening for other autoimmune conditions (SLE, Sjögren's syndrome) that could independently cause renal disease in LP patients 5.
• Remember that coincidental occurrence is possible given the prevalence of both autoimmune conditions and various causes of interstitial nephritis in the general population 6.

Monitoring Recommendations for LP Patients on Immunosuppression

• For patients on sulfasalazine or 5-ASA: monitor renal function every 4 weeks during the first 3 months, then every 3 months for the first year, then annually 1.
• Risk is highest during the first few months of treatment, making early monitoring critical for detecting reversible injury 1.
• Refer to nephrology for unexplained creatinine elevation or progressive cytopenias to evaluate for autoimmune causes 1.