A case of atypical IgG4-related disease presenting hypereosinophilia, polyneuropathy, and liver dysfunction.

Ig (immunoglobulin) G4-related disease (Ig4-RD) affects several organs, including salivary glands, lacrimal glands, pancreas, biliary ducts, and retroperitoneum. A 72-year-old woman was examined for hypereosinophilia, high levels of IgG4, polyneuropathy, liver dysfunction, enlargement of lymph nodes and lacrimal glands, and beaded dilation of the bile ducts. We diagnosed Ig4-RD based on biopsies of the lymph nodes, liver, and submandibular gland. The symptoms of the patient improved after glucocorticoid treatment. This was a novel and atypical case of Ig4-RD that was difficult to differentiate from other diseases, including eosinophilic granulomatosis with polyangiitis, idiopathic hypereosinophilic syndrome, and polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes syndrome. This case report highlights the importance of biopsies in differentiating Ig4-RD.