A Case of IgG4-Related Disease Presenting with Skin Lesions and Proptosis as Initial Manifestations.

Background: IgG4-related disease (IgG4-RD) is a rare chronic fibroinflammatory disorder. Elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells into affected tissues are characteristic of it. It often involves multiple organs. However, initial presentations with cutaneous involvement are relatively rare. To better understand and treat the associated disease, we report this case. Patients and Methods: We report a 39-year-old man who presented with a 3-year history of pruritic papules and nodules on the face, neck, shoulders, back, and lower extremities, along with progressive bilateral proptosis over the past year. He had a known history of allergic rhinitis. Previously diagnosed with "atopic dermatitis" at another hospital, he was treated with antihistamines and topical glucocorticoids, which produced minimal improvement. At our hospital, he underwent serum IgG4 testing,imaging studies,pathological examination, and multidisciplinary consultations involving dermatology, ophthalmology, and hematology, leading to a definitive diagnosis of IgG4-RD. Results: Systemic glucocorticoids and methotrexate, along with topical medications,therapy resulted in marked clinical improvement in both skin and ocular symptoms, along with gradual normalization of serum IgG4 levels. Conclusion: IgG4-RD can mimic a variety of diseases, through this case we found that this disease in addition to the reported diseases, but also mimic atopic dermatitis manifestations with intense itching makes it very easy to misdiagnose, missed diagnosis, which not only presents a complete multidisciplinary collaboration in the diagnosis and treatment of atopic dermatitis-like clinical diagnostic ideas of IgG4-RD, but also for the first time systematically reported the skin lesions of dermatoscopy and CT imaging features of skin, for clinical.