Antineutrophil Cytoplasmic Antibody-Associated Vasculitis With Immunoglobulin G4 Involvement in Lacrimal Sac Squamous Cell Carcinoma.

Lacrimal sac squamous cell carcinoma is a rare but life-threatening disease that is often a delayed diagnosis secondary to difficulty in differentiating from other causes of dacrocystitis and acquired nasolacrimal duct obstruction. Chronic inflammation, including that of an underlying autoimmune disease, prior instrumentation, and poor wound healing, may be risk factors in the development to lacrimal sac squamous cell carcinoma. The authors present the first case of lacrimal sac squamous cell carcinoma associated with antineutrophil cytoplasmic antibody-associated vasculitis and immunoglobulin G4 positivity. Rather than an overlap syndrome between antineutrophil cytoplasmic antibody-associated vasculitis and immunoglobulin G4-related disease, high immunoglobulin G4 positivity may be considered an inflammatory marker of disease severity in the setting of antineutrophil cytoplasmic antibody-associated vasculitis and underlying malignancy. Inflammation-mediated tumorangiogenesis should be considered in the development of malignancy and red flags of chronic uncontrolled inflammation should warrant a lower threshold for further workup.