Is there an association between oral bullous pemphigoid and interstitial nephritis, particularly in older adults with a history of autoimmune diseases?

No Established Association Between Oral Bullous Pemphigoid and Interstitial Nephritis

There is no conclusive evidence for an association between bullous pemphigoid and other autoimmune diseases, including interstitial nephritis. 1, 2

Evidence Against Association

The British Association of Dermatologists' 2012 guidelines explicitly state that there is no conclusive evidence for an association between bullous pemphigoid and other autoimmune diseases. 1, 2 This represents the highest quality guideline evidence available on this topic and should guide clinical decision-making.

Rare Case Reports of Renal Involvement

While the guideline evidence is clear, isolated case reports from 1989 describe two patients with bullous pemphigoid who had concurrent renal pathology (membranous glomerulopathy and allograft rejection with membranous changes). 3 However, these cases involved glomerular disease, not interstitial nephritis, and the authors acknowledged that multiple distinct autoimmune processes could not be excluded. 3

Critical Distinction

• The 1989 case reports describe glomerular basement membrane involvement (membranous glomerulopathy), not tubulointerstitial disease. 3
• The proposed mechanism involved anti-basement membrane antibody cross-reactivity between skin and glomerular basement membranes. 3
• This is fundamentally different from interstitial nephritis, which primarily affects the renal tubules and interstitium rather than glomerular structures.

Clinical Implications for Older Adults

In elderly patients with bullous pemphigoid who develop renal dysfunction:

• Consider drug-induced causes first: Multiple medications associated with bullous pemphigoid (furosemide, spironolactone, neuroleptics) can independently cause interstitial nephritis. 1, 2
• Evaluate for chronic kidney disease: CKD is common in elderly patients and requires dose adjustments for systemic therapies. 4
• Monitor renal function closely: Systemic corticosteroids used to treat bullous pemphigoid can worsen electrolyte imbalances and hypertension in patients with underlying renal disease. 4

Common Pitfall to Avoid

Do not assume that concurrent bullous pemphigoid and interstitial nephritis represent a unified autoimmune process. 1, 2 The far more likely explanation in elderly patients is:

• Drug-induced interstitial nephritis from medications triggering or treating the bullous pemphigoid 1, 2
• Age-related chronic kidney disease occurring independently 4
• Corticosteroid-related complications affecting renal function 4