We explored an intriguing instance of IgG4-related disease (IgG4-RD) manifesting as Mikulicz syndrome in an 85-year-old male patient. This condition usually involves significant systemic symptoms, yet our patient exhibited primarily local manifestations, specifically bilateral dacryoadenitis and orbital pseudotumor, without major organ complications.
Interestingly, despite normal serum IgG4 levels, which were below 135 mg/dL, the clinical and imaging findings strongly suggested the diagnosis of IgG4-RD. This scenario underscores the importance of undertaking a biopsy for accurate diagnosis. Histopathological examination revealed notable signs, such as a dense lymphoplasmacytic infiltrate and storiform fibrosis, with a considerable percentage of IgG4-positive cells, ultimately confirming our diagnosis.
We observed that treatment with prednisone, alongside azathioprine for long-term control, was effective. To mitigate the risk of glucocorticoid-induced osteoporosis, we added calcium and vitamin D3 supplementation. Remarkably, the patient showed significant clinical improvement within just 24 hours, with resolution of orbital and glandular symptoms over the following year. There was a complete recovery of vision and no relapses, with only minor dry eye as a long-term concern.
This case demonstrates the necessity of considering IgG4-RD even when serum IgG4 levels are normal and highlights the role of histopathology in diagnosis. Furthermore, it showcases the effectiveness of corticosteroids as a first-line treatment in managing this condition.