Kimura's disease of the lacrimal gland mimicking IgG4-related orbital disease

Background: Kimura's disease (KD) is a rare and benign chronic inflammatory soft tissue disorder of unknown origin, which predominantly inflicts young male adults in Asia. IgG4-related disease is a new disease concept, established this century and characterized by fibrosis and sclerosis of the involved organs, with infiltration of IgG4-positive plasma cells. These two kinds of diseases share similar characteristics, which may complicate their diagnosis. Case presentation: A 47-year-old Chinese man presented to our Department of Ophthalmology with a 26-month history of painless swelling and redness left upper eyelid. Surgical excisions of the left lacrimal gland were performed. A histopathology examination showed follicular hyperplasia with reactive germinal centres and eosinophilic infiltration involving the interfollicular areas as well as proliferation of post capillary venules, all signs of Kimura disease. Immunohistochemical analysis of the cells demonstrated positive staining for CK, Vimentin, CD3, CD4, CD20, CD21, CD117, CD5, CD8, CD23, IgG and IgG4 (30 per high-power field) and negative staining for CD10 and CD34. Some ophthalmologists in our department questioned whether the histological and immunohistochemical findings were also compatible with features of IgG4-related diseases. There was no sign of recurrence during the twelve months of regular follow-up. Conclusion: Kimura's disease may present with high serum IgG4 levels, which may be an epiphenomenon related to chronic antigen exposure. As clinical doctors, especially ophthalmologists, we should recognize the possibility of the occurrence of increased serum levels of IgG4 in Kimura's disease to ensure correct diagnosis.