Systemic disorders with rheumatic manifestations: Edited by John Stone and Arezou KhosroshahiPathological features of IgG4-related sclerosing diseaseSmyrk, Thomas CAuthor Information Department of Pathology, Mayo Clinic, Rochester, Minnesota, USA Correspondence to Thomas C. Smyrk, MD, Associate Professor of Pathology, Mayo Clinic, Rochester, MN 55902, USA Tel: +1 507 255 3831; e-mail: firstname.lastname@example.org Current Opinion in Rheumatology: January 2011 - Volume 23 - Issue 1 - p 74-79 doi: 10.1097/BOR.0b013e328341347b Buy Metrics Abstract Purpose of review The spectrum of IgG4-related systemic disease (IgG4-RSD) continues to widen. At most of the sites involved by this condition, the clinical presentation can mimic neoplasm. Pathologic assessment of small biopsies can be critical to proper management. This review summarizes the histologic features of IgG4-RSD and the role of immunohistochemistry of IgG4 in the diagnosis. Recent findings The review period saw further expansion of the list of sites putatively involved by IgG4-RSD, with new, or more detailed, entries related to lung, lymph nodes, stomach, and thyroid. A tentative consensus was reached on the issue of subtypes of autoimmune pancreatitis. The role of immunohistochemistry for IgG4 as an adjunct to the diagnosis of IgG4-RSD was further clarified. Summary Sclerosing lymphoplasmacytic inflammation at almost any site can represent a manifestation of IgG4-RSD. There are several histologic features that can suggest the diagnosis. Immunohistochemistry for IgG4 is a useful diagnostic test to further support the diagnosis. © 2011 Lippincott Williams & Wilkins, Inc.