Morphological heterogeneity of IgG4-related hepatobiliary disease: further expanding the spectrum

Immunoglobulin G4-related disease (IgG4-RD) is a distinct immunoinflammatory disorder of unknown aetiology that may involve one or more organs, either synchronously or metachronously. Nonetheless, the pathophysiological mechanism is complex and poorly understood. The hepatobiliary manifestations of IgG4-RD [IgG4-hepatobiliary (IgG4-HB)], per se, have been sporadically reported in the literature. We describe the clinicoradiological, histomorphological, serological, and therapeutic data of 16 cases of IgG4-HB diagnosed on needle core liver biopsies applying 2021 Japanese guidelines. These included 11 cases of IgG4-sclerosing cholangitis (IgG4-SC), two with IgG4-sinusoidal dilatation and congestion (IgG4-SDC) in the absence of increased IgG4+ plasma cells in tissue but raised in serum, and three cases of IgG4-autoimmune hepatitis (IgG4-AIH). There was a male preponderance (M/F=11/5), with a median age at diagnosis of 49.5 years (13-73). On imaging, mass lesions mimicking a pseudotumour (n=6) or even cholangiocarcinoma (n=3) and biliary stricture (n=9) were common in the IgG4-SC subgroup. There was a positive but insignificant correlation between serum and tissue IgG4 levels (Spearman r=0.24, p=0.37), although increasing serum IgG4 levels were associated with biliary stricture (p=0.653). There was a satisfactory response to steroid therapy among 12 of 14 cases (median duration of follow-up 16.5 months). To the best of our knowledge, this represents the largest histomorphological series of IgG4-HB on needle biopsy from a single tertiary care centre in India. A larger prospective study with longer follow-up data is needed to validate our observations.