RHEUMATOLOGY
IGG4-RELATED DISEASE
Definition & etiology (NEJM 2012;366:539)
• Responsible for tumor-like inflammatory lesions of nearly every organ/tissue
• Etiology unclear: ? autoimmune; unclear role of IgG4 Ab; may have h/o atopy
Clinical manifestations
• Commonly pancreatitis, aortitis, cholangitis, sialadenitis, orbital structures, retroperitoneal fibrosis
• Multiple lesions may be present synchronously or metachronously
Diagnosis (Mod Pathol 2012;25:1181)
• Biopsy w/ specific histopathology & immunohistochemistry findings: lymphoplasmacytic infiltrate w/ significant IgG4+ plasma cell infiltrate, fibrosis, obliterative phlebitis
• ↑ serum IgG4 in 40%; not specific seen in GPA, bronchiectasis, etc (Modern Rheum 2012;22:419)
Treatment
• Prednisone vs. rituximab (Medicine 2012;91:57)