Linear IgA Disease with Oral and Laryngeal Mucosal Involvement in an Elderly Denture Wearer: A Case Report and Literature Review

Background and Clinical Significance: Linear IgA disease (LAD) is a rare autoimmune subepithelial blistering disorder characterized by linear IgA deposition along the basement membrane zone (BMZ). Oral and laryngeal involvement is exceptionally rare and can mimic other autoimmune blistering diseases. We report such a case and review previously published cases. Case Presentation: An 85-year-old denture-wearing woman with ulcerative colitis (UC) and chronic oral erosions since 2019 underwent clinical, histopathological, immunofluorescence, and serological evaluations, as well as laryngoscopy. Medication exposure and denture-related injury were reviewed as possible triggers. Previously diagnosed as oral lichen planus (OLP) and bullous pemphigoid (BP), the lesions showed strong linear IgA (3+) and moderate C3 (2+) deposition along the BMZ on direct immunofluorescence (DIF); serological tests for pemphigoid and pemphigus antigens were negative. Laryngoscopy revealed edema, fibrinous deposits, and early scarring. After drug-related and denture-related causes were considered unlikely, a clinicopathologic diagnosis of mucosal-predominant LAD was made; because salt-split skin indirect immunofluorescence (IIF) and antigen-specific testing were unavailable, IgA-predominant mucous membrane pemphigoid (MMP) could not be completely excluded. Dapsone produced marked improvement but was discontinued because of severe hemolytic anemia; laryngeal edema later caused respiratory insufficiency. A structured literature review of English-language reports published since 2016 identified three previously reported cases of LAD limited to the oral mucosa. No prior case with simultaneous oral and laryngeal involvement without skin disease was identified, although one report described LAD confined to the hypopharyngeal and laryngeal mucosa. Conclusions: DIF is essential for diagnosis, LAD must be distinguished from IgA-predominant MMP, and laryngeal involvement requires early recognition. Because linear IgA deposition in adults may be reactive, drug-induced and denture-related injury should be excluded, and dapsone toxicity monitored.