Abstract Background IgG4-related disease (IgG4-RD) is a recently described, rare systemic fibroinflammatory disorder, with an estimated incidence of less than 1 in 100,000 persons per year. While IgG4-RD can affect virtually any organ, thoracic involvement is detected in up to 30% of patients, and is the exclusive manifestation in only ∼10% of cases. Pathologically confirmed IgG4-related lung disease (IgG4-RLD) is even less common, with an incidence of only 0.2% in a large review of pulmonary specimens. The clinical and radiologic heterogeneity of IgG4-RLD makes diagnosis challenging, as it may mimic malignancy or other inflammatory conditions. Case Presentation A 56-year-old man with biopsy-proven IgG4-related orbital disease, chronic rhinitis, type II diabetes, hypogonadism, and hyperlipidemia presented for evaluation of possible IgG4-RLD. Orbital disease was initially diagnosed in 2016 via orbital fat biopsy demonstrating 50 IgG4-positive plasma cells per high-power field. Corticosteroid therapy initially induced remission but was discontinued due to hyperglycemia; rituximab was administered in 2019.In early 2024, he developed recurrent orbital swelling and mild visual decline. CT chest (3/29/24) revealed multiple scattered small ill-defined pulmonary nodules in both lungs, predominantly in the right lung measuring up to 1.3 cm, with mild mediastinal and right hilar lymphadenopathy. Comparison with CT from 2016 showed unchanged nodules over five years, resolution of prior basilar scarring, and no new masses, indicating a chronic, indolent process.The patient reported mild cough and nocturnal wheezing without dyspnea or hemoptysis. Spirometry showed mild airflow obstruction with a significant bronchodilator response and normal diffusing capacity, while serum IgE and allergen testing were negative. Lung biopsy was deferred given small, stable nodules and established systemic IgG4-RD.He resumed rituximab therapy, and at 3-month follow-up, he reported marked improvement in breathing, including reduced cough and wheezing, improved exertional tolerance, and better pulmonary function metrics. Inhaled budesonide-formoterol (Symbicort) was continued for airway support. Conclusion This case represents a rare presentation of IgG4-RLD in a patient with biopsy-proven orbital IgG4-RD and chronic, stable pulmonary nodules, highlighting the diagnostic complexity and clinical heterogeneity of this uncommon disease. The patient’s early symptomatic improvement following rituximab underscores its efficacy in managing both orbital and pulmonary manifestations. This report emphasizes the importance of multidisciplinary evaluation, longitudinal imaging, and functional assessment in identifying and managing IgG4-RLD, a condition that is infrequently encountered in clinical practice but may mimic more common pulmonary pathologies. This abstract is funded by: None
Abushamma et al. (Fri,) studied this question.