Labial salivary gland biopsy for diagnosing immunoglobulin G4-related ophthalmic disease with optic neuropathy: a case report.

Immunoglobulin G4 (IgG4)-related ophthalmic disease (IgG4-ROD) typically affects the lacrimal glands, trigeminal nerves, and extraocular muscles. Although imaging and serology aid in diagnosis, histopathological confirmation is crucial. Recent updates to the diagnostic criteria have incorporated labial salivary gland biopsy as a biopsy site. We report a case of IgG4-ROD with optic neuropathy diagnosed via labial salivary gland biopsy. A 69-year-old male patient presented with progressive right-eye visual loss. Imaging revealed an orbital mass, enlarged extraocular muscle, and enlarged infraorbital nerve. Serum IgG4 level was elevated, and a labial salivary gland biopsy was performed due to the absence of accessible biopsy sites, confirming the diagnosis. Oral corticosteroid therapy resulted in rapid visual and imaging improvement with no recurrence. This case emphasizes the diagnostic value of infraorbital nerve enlargement and the utility of labial salivary gland biopsy in IgG4-ROD, highlighting the importance of early recognition and treatment to prevent irreversible visual damage.