Lymph node granulomas in immunoglobulin G4-related disease

Aims: Immunoglobulin (Ig) G4-related disease (IgG4-RD) is an increasingly recognized fibroinflammatory condition that commonly exhibits multisystem involvement, with localized (e.g. inflammatory pseudotumours that can mimic malignancy) or diffuse (leading to organ dysfunction) patterns of tissue involvement. The 2012 Boston criteria have standardized the histopathological approach to the diagnosis of IgG4-RD and require one or more of the cardinal morphological features with prominence of IgG4(+) plasma cells and an IgG4(+)/IgG(+) plasma cell ratio of at least 40%. The relative prevalence of the morphological criteria varies between anatomical sites, but granulomas are rarely found and, indeed, their presence would usually deter a pathologist from making this diagnosis. The aim was to characterize two cases of IgG4-RD in which granulomas were present and to highlight this as an unusual feature of the condition. Methods and results: We describe two cases in which the features of IgG4-RD were present within lymph nodes, together with granulomas. This is a recognized but rare morphological pattern of IgG4-RD. Conclusions: While an unusual finding, the presence of granulomas should not preclude a diagnosis of IgG4-RD in the appropriate clinicopathological context.