A Rare Manifestation of IgG4-Related Disease and Secondary Hypereosinophilic Syndrome: A Case Report.

We report a case of IgG4-related disease with marked eosinophilia. A 79-year-old woman was admitted due to diarrhea, and weight loss. Cervical lymphadenopathy, bilateral submandibular glands swelling, anemia (Hb8.5g/dl), hypereosinophilia (9,750/μL), and elevated serum creatinine (1.57 mg/dL), pancreatic amylase (191 IU/L), and IgG4 (3,380 mg/dL) were found. Diffusion-weighted image on MRI showed high intensity signals inside of both the pancreas and the kidney. The echogram of submandibular glands revealed cobblestone pattern. Kidney biopsy revealed acute tubulointerstitial nephritis. Biopsies of lip, gastrointestinal tract and bone marrow showed infiltration of lymphoplasmacytic cells and IgG4 positive plasma cells (30-67/HPF). Gastrointestinal and bone marrow biopsies also showed eosinophilic infiltration. Adrenal insufficiency, rheumatic disease, tuberculosis, parasite infection, drug induced eosinophilia, and eosinophilic leukemia were all ruled out. We started treatment with 40mg of prednisolone and her general condition rapidly improved. The eosinophil count, serum IgG4, and serum creatinine decreased. We gradually tapered prednisolone and maintained 5mg/day. During the 5 years of treatment, she had no recurrence of the symptom. According to the 2019 American College of Rheumatology/European League Against Rheumatism classification criteria for IgG4-related disease, eosinophils > 3000/μL is one of the exclusion criteria. If we comply this criterion, the diagnosis of IgG4-related disease should be avoided. However, our case fit the diagnostic criteria of type I autoimmune pancreatitis, IgG4-related sialadenitis and global diagnosis of IgG4-related disease. We finally diagnosed our case as IgG4-related disease with secondary hypereosinophilic syndrome. This case suggests that IgG4-related disease with eosinophils > 3000/μL does exist in the real world.