IgG4-Related Sialadenitis Is Rare: Immunohistological Investigation of 105 Cases of Chronic Submandibular Sialadenitis
Manuel Rodriguez-Justo, John D Harrison. University College London Hospitals & Faculty of Biomedical Sciences UCL, London, United Kingdom; King's College London Dental Institute, London, United Kingdom
Background: Chronic sialadenitis is a relatively common disease in which microliths play an important role in its pathogenesis. The suggestion that all cases of chronic sclerosing sialadenitis are IgG4-related sialadenitis is not supported by evidence, and we have recently reported a case with the histological features of chronic sclerosing sialadenitis that lacked significant numbers of IgG4 plasma cells (Histopathology 2011, 58: 1164-6).
Design: We have undertaken an investigation of an archive of 105 cases of chronic submandibular sialadenitis that had been previously extensively characterized (Histopathology 1997, 31:237-51). The degree of fibrosis, periductal lymphoplasmacytic infiltrate, and the presence or absence of liths, granulocytic epithelial lesions (GEL) and phlebitis were assessed. The number of IgG4 plasma cells was counted in 10 HPFs and samples were classified as “0”: no IgG4 plasma cells, “1”: scattered IgG4 cells and; “2”: > 50 IgG4 cells per HPF. The ratio IgG4:IgG was also investigated.
Results: The degrees of inflammation, atrophy and fibrosis varied greatly, and 67 cases were classified as chronic sclerosing sialadenitis. Sialoliths were present in 63 out of 89 cases in which the presence or absence of sialolithiasis could be confirmed. The number of IgG4 plasma cells was “0” in 89 cases, “1” in 19 cases, and “2” in three cases, in which there was sialolithiasis. There were relatively more widespread atrophy, fibrosis and inflammation and more sialoliths in glands with IgG4 cells described as 1 than in glands with 0. There was widespread atrophy, fibrosis and inflammation in the 3 glands with IgG4 cells above 50 per HPF, which surrounded the ducts that contained sialoliths.
Conclusions: The incidence of IgG4-related sialadenitis is unknown with about 52 cases reported in the literature. However, our investigation adds further evidence that IgG4-related sialadenitis is rare. In addition, our findings raise the possibility that IgG4 plasma cells represent a local reaction to sialolithiasis rather than a systemic process in the three cases with significant numbers of IgG4 plasma cells.
Category: Head & Neck
Tuesday, March 20, 2012 1:00 PM
Poster Session IV # 164, Tuesday Afternoon