case_images: PMC6165622_01
case_images: Imaging findings in a patient with IgG4-related sclerosing cholangitis (IgG4-SC). (a) At magnetic resonance imaging, no tumor-like lesions are seen. A benign hepatic cyst is indicated (1). (b) Diffuse and multiple intrahepatic biliary stenoses and dilatations at endoscopic retrograde cholangiography (1). The stenoses are relatively long. In classical primary sclerosing cholangitis (PSC), the stenoses would have been shorter, giving the cholangiogram a more beaded appearance. No complete obstruction of a bile duct is seen, a finding that would have been more characteristic of bile duct carcinoma. 2: occlusive balloon, 3: endoscope, 4: guide wire.
case_images: CRIPA2018-2309293.001.jpg
case_images: PMC6165622_01_CRIPA2018-2309293.001.jpg
case_images: fig1
case_images: Bismuth-Corlette type IV in the hilar region, involving both the right and left hepatic bile ducts. By magnetic resonance imaging (MRI), no hepatic tumors or pseudotumors but a benign cyst were observed (Figure 1(a)). One month later, an ERCP showed multiple strictures of the small intrahepatic bile ducts in several liver segments, dilation of the CBD (12 mm), and a stenosis of the bifurcation (Figure 1(b)).
case_images: Liver core needle biopsy findings in a patient with IgG4-related sclerosing cholangitis (IgG4-SC). (a) A portal inflammatory nodule (IN), showing storiform fibrosis (arrows) and diffuse lymphoplasmacytic infiltration (H&E). (b) Higher magnification of the storiform fibrosis (H&E). (c) Strong infiltration of lymphocytes and plasma cells in the wall of the bile duct (Methyl-Green Pyronin). (d) Deeper section of the same area shown in Figure 2(a). At the periphery of the IN, there is obliterative phlebitis (arrows). Note the wall of the corresponding artery (Verhoeff elastin). (e) Higher magnification of the area with obliterative phlebitis shown in Figure 2(d). The former lumen of the vein is filled with plasma cells and lymphocytes. The vein can only be identified using an elastin stain (Verhoeff elastin). (f) Deeper sections of the area shown in Figure 2(a). Strong infiltration of IgG4-positive cells in the IN. (g, h) The IgG4 / IgG ratio is 72%.
case_images: CRIPA2018-2309293.002.jpg
case_images: PMC6165622_01_CRIPA2018-2309293.002.jpg
case_images: fig2
case_images: To further investigate the possibility of an autoimmune etiology, particularly of IgG4-SC, a liver CNB was obtained (Figure 2). A portal-based, expansile inflammatory nodule (IN) measuring 6 mm in largest dimension, leading to expansion of a portal tract due to storiform fibrosis and lymphoplasmacytic infiltration, was identified (Figures 2(a) and 2(b)). In the bile duct located inside the IN, strong infiltration with lymphocytes and plasma cells was observed (Figure 2(c)). Obliterative phlebitis was identified (Figures 2(d) and 2(e)) and, in addition, venolitis. Immunohistochemically, there was diffuse infiltration with IgG4-positive plasma cells (Figure 2(f)). Hot spots revealing 339 IgG4-positive and 468 IgG-positive plasma cells per high power field (HPF, 0.2 mm2) were found, corresponding to an IgG4/IgG ratio of 72% (Figures 2(g) and 2(h)).
case_images: Histological findings in a patient with IgG4-related lymphadenopathy. (a) Low magnification showing expansion of the interfollicular zone (H&E). (b) At higher magnification, numerous plasma cells are identified in the interfollicular zones (H&E). (c, d) Strong infiltration of IgG4-positive cells, hot spot (c) (IgG4 immunostaining) and IgG-positive cells, hot spot (d) (IgG immunostaining). The IgG4 / IgG ratio is 92%. (e) A granulomatous focus, arranged in a ring-like fashion around a lymphoid follicle, is shown, a feature called perifollicular granuloma (H&E). (f) Another perifollicular granuloma, accompanied by numerous IgG4-positive cells (IgG4 immunostaining).
case_images: CRIPA2018-2309293.003.jpg
case_images: PMC6165622_01_CRIPA2018-2309293.003.jpg
case_images: fig3
case_images: The lymph node was retrieved from the archive and showed expanded interfollicular zones as well as follicular hyperplasia with activated germinal centers (Figure 3(a)). Interfollicular zones as well as follicles were infiltrated by an increased number of plasma cells (Figure 3(b)). Immunohistochemically, hot spots revealing 593 IgG4-positive and 646 IgG-positive plasma cells per high power field (HPF, 0.197-0.199 mm2) were found, corresponding to an IgG4/IgG ratio of 92% (Figures 3(c) and 3(d)). These granulomatous foci were arranged in a ring-like fashion around lymphoid follicles, a feature also called perifollicular granuloma (Figure 3(e)). However, perifollicular granulomas are an exception, as they have been reported in a number of cases of IgG4-related lymphadenopathy.  Figure 3(f) shows that the perifollicular granulomas were accompanied by numerous IgG4-positive cells.