Autoimmune Diseases/diagnosis; Common Bile Duct Diseases/pathology; Hypergammaglobulinemia/diagnosis; Immunoglobulin G/blood; Lymphoproliferative Disorders/diagnosis; Sclerosis/diagnosis; Adult; Ampulla of Vater/metabolism; Ampulla of Vater/pathology; Autoimmune Diseases/drug therapy; Autoimmune Diseases/immunology; Common Bile Duct Diseases/drug therapy; Common Bile Duct Diseases/immunology; Diagnosis, Differential; Glucocorticoids/therapeutic use; Humans; Hypergammaglobulinemia/drug therapy; Hypergammaglobulinemia/immunology; Jaundice, Obstructive/diagnosis; Jaundice, Obstructive/drug therapy; Jaundice, Obstructive/immunology; Lymphatic Diseases/diagnosis; Lymphatic Diseases/drug therapy; Lymphatic Diseases/immunology; Lymphoproliferative Disorders/drug therapy; Lymphoproliferative Disorders/immunology; Male; Plasma Cells/metabolism; Plasma Cells/pathology; Prednisolone/therapeutic use; Sclerosis/drug therapy; Sclerosis/immunology; Treatment Outcome