IgG4-Related Disease: A Reminder for Practicing Pathologists

Abstract

IgG4-related disease (IgG4-RD) is a systemic autoimmune fibroinflammatory disease that produces sclerotic, tumefactive masses containing dense lymphoplasmacytic infiltrates rich in immunoglobulin (Ig) G4+ plasma cells. Initially characterized as a form of autoimmune pancreatitis, the distinctive histopathology of IgG4-RD has now been described in almost every organ system. However, because the clinical manifestations of IgG4-RD are diverse and nonspecific, the disease may go unsuspected until a biopsy or resection specimen is obtained to diagnose a presumed malignancy. Pathologists thus play a key role in the diagnosis of IgG4-RD, and familiarity with its histopathologic features is essential to preventing the irreversible comorbidities associated with this treatable disease. This brief review outlines the epidemiology, clinical manifestations, and histopathology of IgG4-RD, with the aim of furthering pathologists' awareness of and ability to diagnose this disorder.

Parathyroid adenoma with prominent lymphocytic infiltrate having histological features highly suggestive of IgG4-related disease: a case report and literature review

“…Dense infiltration of lymphocytes as well as eosinophils, an increased number of IgG4-positive plasma cells with increased IgG4/IgG-positive plasma cell ratio, together with storiform-type fibrosis and obliterative phlebitis are typical histopathological features of IgG4-RD, a fibroinflammatory disorder involving almost all organs [20]. The number of IgG4-positive plasma cell and its ratio to IgG-positive plasma cell are 10-200/highpower field and >40%, respectively, in IgG4-RD [21]. Clinically, the disease commonly manifests as a mass lesion with or without systemic symptoms [21].…”

“…The number of IgG4-positive plasma cell and its ratio to IgG-positive plasma cell are 10-200/highpower field and >40%, respectively, in IgG4-RD [21]. Clinically, the disease commonly manifests as a mass lesion with or without systemic symptoms [21]. Many distinct inflammatory disorders, for example Riedel thyroiditis, have been revealed to be closely connected to IgG4-RD [21,22].…”

Acute Pancreatitis as the Debut of a Pancreatic Lesion

“…However, laboratory does not always show elevated serum IgG4 levels. 6 This form of the disease is more common in Asian countries. Type 2 AIP is also known as idiopathic duct-centric pancreatitis (IDCP).…”

“…This fibrosis has characteristic dense, wire like strands of fibrotic collagen deposition radiating outward from a central point. 6 The presence of storiform fibrosis and obliterative phlebitis are more common in type 1 AIP, but they can also be observed in type 2 AIP.…”

Diagnosis and Management of IgG4-Related Cardiovascular Lesions

“…Storiform fibrosis or obstructive phlebitis, which are characteristic but not exclusive histological features of IgG4-RD, were absent in the biopsied specimens; however, the presence of these findings is known to differ according to the organs examined. 3,4) Subsequent steroid therapy successfully reduced the right atrial mass volume and chest symptom of the patient and also decreased the serum IgG4 level.…”