IgG4-Rich Lesions Associated With Intranasal Drug Use Can Mimic IgG4-Related Disease.

Context.—: Manifestations of immunoglobulin G4-related disease (IgG4-RD) occur in several organ systems and anatomic locations, including the nasal cavity and paranasal sinuses. Other processes affecting the sinonasal tract, such as chronic rhinosinusitis, aspirin-exacerbated respiratory disease, and nasal polyposis, also involve IgG4.

Objective.—: To characterize an association between IgG4 and nasal lesions arising in the clinical context of intranasal drug use.

Design.—: The cases of 3 patients (2 with histories of intranasal cocaine abuse, and 1 with intranasal heroin abuse) were evaluated. Clinical features of each case were compiled from the electronic medical record. Histologic morphology of surgical specimens was examined. Immunohistochemical staining was performed to assess involvement of/association with IgG4.

Results.—: Clinical features of these lesions included diffuse necrotic fibrinous debris, scarring, and endoscopically evident inflammation. Tissue sections showed acutely and chronically inflamed respiratory-type mucosa with abundant IgG4-positive plasma cells. Although these cases share some aspects in common with IgG4-RD, other definitive characteristics are absent, and notable differences exist.

Conclusions.—: This series provides the first demonstration of increased IgG4 expression in nasal lesions associated with intranasal drug use. Despite some similarities, the pathologic processes and IgG4-rich infiltrates in these 3 cases seem to represent a different phenomenon that is not IgG4-RD. Although these lesions contain abundant IgG4-positive cells, they should not be mistaken for or conflated with IgG4-RD.