Proliferation of CD163+ Spindle-Shaped Macrophages in IGG4-Related Sclerosing Disease: Analysis of Lymphoplasmacytic Sclerosing Pancreatitis and Sclerosing Sialadenitis
K Notohara, Y Wani, M Fujisawa. Kurashiki Central Hospital, Kurashiki, Japan; Himeji Red Cross Hospital, Himeji, Japan
Background: To date, types of lymphocytes and plasma cells have been highlighted as a cause of IgG4-related sclerosing disease, but little has been discussed on the role of macrophages.
Design: Resected specimens from 15 patients with lymphoplasmacytic sclerosing pancreatitis (LPSP) and 9 with IgG4-related sclerosing sialadenitis (ISS) were immunostained for CD163, CD68, α-smooth muscle actin (SMA) and IgG4. For comparison, idiopathic duct-centric chronic pancreatitis (IDCP; 2 patients), pancreatic ductal carcinoma (PDC; 10) and sialolithiasis-associated sialadenitis (SAS; 10) were studied simultaneously.
Results: In LPSP and ISS, numerous CD163+ macrophages were observed throughout the lesion, except for two cases. Most of them were spindle-shaped, and were different from those macrophages with abundant cytoplasm. Thus they morphologically resembled mesenchymal cells. Compared to typical myofibroblasts, however, they were more slender and possessed a smaller nucleus. CD163+ spindle-shaped macrophages tended to be clustered and showed a storiform growth pattern in storiform fibrosis, heavily inflamed lobules and pancreatic periductal inflammation. Lymphocytes and plasma cells, including those with IgG4 expression, were admixed with the CD163+ macrophages. Proliferation of SMA+ myofibroblasts with fibrosis was, on the other hand, confined to areas with scarce inflammatory cells, and were absent in foci with abundant CD163+ macrophages. Typically, the more intense lymphoplasmacytic infiltration was in each case, the more CD163+ cells and the less SMA+ cells were found. In two cases (one each of LPSP and ISS) with scarce CD163+ cells, the inflammation was entirely regressive. Nevertheless, small foci with numerous CD163+ cells were focally identified in these cases. Immunostaining for CD68 labeled only a portion of CD163+ macrophages. In IDCP, PDC and SAS, CD163+ spindle-shaped macrophages were fewer and dispersed mainly around the lobules and in fibrosis. However, in one case of PDC with LPSP-like reaction, the distribution of CD163+ cells was similar to LPSP.
Conclusions: CD163+ spindle-shaped macrophages are one of the major inflammatory components of LPSP and ISS, and contribute to forming the unique histology of ISD, such as storiform fibrosis. The proliferation of CD163+ macrophages seen in ISD is unique, and thus CD163 could be a useful marker for the histological diagnosis of ISD.
Category: Liver & Pancreas
Tuesday, March 23, 2010 1:00 PM
Platform Session: Section C, Tuesday Afternoon