Infraorbital nerve enlargement in a patient with IgG4-related disease.

IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory condition characterised by distinctive histopathological features and diverse clinical presentations. Although it is frequently associated with bilateral swelling of the lacrimal and submandibular glands, it has occasionally been reported to affect adnexal tissues, such as infraorbital nerve enlargement (IONE), which has not yet been well recognised. A 54-year-old woman presented with purpura. Laboratory investigations revealed eosinophilia, elevated serum creatinine, hypergammaglobulinemia with markedly elevated serum IgG4 levels (2 924 mg/dl), and hypocomplementemia, along with increased levels of β2-microglobulin and N-acetyl-β-D-glucosaminidase in her urine. Computed tomography revealed the presence of bony tunnel-like structures bilaterally in the infraorbital region, measuring up to 12 mm in diameter. Renal biopsy showed bird's-eye pattern fibrosis and marked infiltration of IgG4-positive plasma cells within the tubulointerstitium. Although an infraorbital nerve biopsy was not performed, the patient was diagnosed with IgG4-RD with tubulointerstitial nephritis, clinically complicated by IONE. Treatment with high-dose glucocorticoids and rituximab led to improvement in the renal manifestations; however, IONE remained unchanged even after six months of treatment. This case highlights an important aspect of IONE in IgG4-RD and offers insights into its clinical diagnosis and management.