IgG4-associated prostatitis complicating autoimmune pancreatitis.

A 65-year-old man underwent transurethral resection of the prostate on a diagnosis of benign prostatic hypertrophy. Almost simultaneously, a diagnostic resection of minor salivary glands was performed. After the resections he suffered from obstructive jaundice. Laboratory examinations revealed an increase in eosinophils and an elevation of serum IgG4. Pancreaticoduodenectomy was performed because of the possibility of pancreatic cancer. The prostate, salivary glands and pancreas showed common histological characteristics, namely, infiltration of lymphocytes and plasma cells accompanying dense fibrosis. Most of the infiltrating plasma cells showed strong immunoreactivity to IgG4. This is the first case with IgG4-associated prostatitis complicating autoimmune pancreatitis.